Artificial Eye (Ocular Prosthesis)

By Chandrashekhar Chawan

1 HISTORY

Since ancient times Artificial Eyes have been used to escape the terror of stigmatisation due to Ocular Disfigurement. The Artificial Eyes used to be made of gold and precious stones.

In India there are references to artificial eye or eye transplant, dating back to 5600 BC from Shalivahan Shaka Parva in the book called “Garbhopanishad” written by Shri Garbbhacharya in 2 BC. One can find references to artificial eyes and eye transplants.

In Takshashila region during Shri Chanakyas time one Nilakumari mentions in her book called “Neelavati” an operation which she performed on an 8 year old girl who had lost her eye due to penetrating injury.

In 444 AD in Nalanda Vidyapith Shri Nagarjunbharda was in-charge of Human Medicine and Animal Medicine and used to perform eye surgery.

In 632 AD Shri Charak, Shri Shushrut and Shri Vagbhat were among the leading cosmetic surgeons who performed many operations on humans to cure disfigurement.

King Shashankdev of Vikramshila region has awarded an eye made of gold as a trophy to Acharya Prashastpad , in 633 AD, for his work in eye surgery on patients who had lost their eyes due to small pox.

Goat’s eyes wrapped in some ‘keratin’ substance and implanted in the eye socket gave the effect of a natural eye; however this type of cosmetic eye is smaller than the natural human eye. This is referred to in the book “Sughatan Shalyachikitsa”.

The Vikramshila Dynasty was destroyed in 1210 AD by the Moguls and all the knowledge and most of the books written on “Tadapatra” (large tree leaves dried and cured) were burnt by the Mogul invaders.

Since 1446 Portuguese Doctors introduced their system of medicine. From 1670 the British introduced the Greek Medicine which is followed to this day.

Technical developments, in the 18th and 19th centuries, in medicines and medical technologies accelerated the general developments.

It is an interesting thought that, if the best of all the medical systems available today, were to be integrated to develop a single system, for the betterment of the human society.

Ludwig Muller, a glass blower, used to make doll’s eyes, developed cryolite glass eyes. The breakage problems of glass led to the development of new materials.

Germany was the major supplier of glass eyes. During world II, the glass eye supply became scarce and technologist started experimenting with plastics.

Now all over the world Artificial Eyes are made of PMMA (poly methyl methacrylate) and only in some parts of Europe and Germany glass eyes are still manufactured.

PMMA is found to be biocompatible material, is non-allergic and gives life like effect to artificial eyes.

Readymade artificial eyes are made in large quantities to stock and are available in the market since 40-50 years. Though they are cheap and easily available they cannot be fitted to all, certainly not to special cases, and if fitted present problems such as excessive eye discharge, poor comfort, poor cosmetic matching, restricted wearing periods and reduced translate ocular movement. In the long run they cause sagging of the lower lid and in some cases contracted eye socket.

Depending on the chain of polymers the quality of PMMA is determined. A simple acryl ate is brittle and breaks easily. Whereas, High Density Medical Grade PMMA is very useful for making an artificial eye.

The stock eyes available in the market today are made from low-grade plastic. Hence they become discoloured and develop cracks after a few years and need frequent replacements.

For making Custom made artificial eyes a High-Density Medical Grade PMMA is used, in order to overcome all the problems of simple acrylic. It is not only tough but also very clear like glass, hence gives a more natural look to the Artificial Eye.

As the art and science of Ocular Prosthesis is making progress all over the world, people are becoming aware of the advantages of custom made artificial eye, and are using them for cosmetic rehabilitation. The role of the “stock eye” is becoming limited around the world and they are

used as a “stop gap” arrangement initially, till a “Custom Made Artificial Eye” is prepared.

I India and other developing countries large number of patients have to depend on stock eye as the number of Ocularists fitting custom made artificial eye is limited.

2 ANATOMY AND PHYSIOLOGY OF THE EYE

The sense of vision is based on a step-wise process in which rays of light are focused on the Retina, where it is converted in to an electrical signal and is conveyed through the visual pathways to the brains occipital cortex. This signal is interpreted as a visual message by the brain. If any part of the system is affected by a disease, vision may be impaired.

As an Ocularist one should know the parts of the eye, its surrounding tissues, and its connections in the brain. As each part is described, you will know its structure (anatomy), function (physiology) and how it can become diseased (pathology).

The Ocular Adnexa (Fig. 1.1)

Ocular adnexa is the tissue surrounding the eye, it protects and preserves the normal function of the eyes. The Ocular Adnexa include:

Eyelids and Conjunctiva Lacrimal apparatus Orbit Extraocular muscles

The Eyelids and Conjunctiva

The eyelids are moving folds of soft tissue that protect the outer portion of the eyeball from injury, exclude light and lubricate the front surface of the eye.

The blinking action of the upper lid spreads lubricating tear film over the front surface of the eye.

The elliptical opening between the upper and the lower lids is called the “Palpebral Fissure”. The normal size of the palpebral fissure is about 15 mm when the lids are open.

The inner junction of the lids is called the “Medial Canthus” and the outer junction is called the “Lateral Canthus”. The medial canthus contains

folds of fleshy tissue. The deeper one is called the “Plica Semilunaris” (semi-lunar fold) and the more visible one is the “Caruncle” . The medial lid margins of the upper and lower lids contain small openings to the tear drainage system that is called the “Puncta”.

The anterior edge of the lid margins contains the hair follicles for the eyelashes (cilia). The lashes serve to sweep airborne particles away from the eye during a blink. Oil secreting glands called “Meibomian Glands” are situated on the posterior edge of the lid margin. Just in front of these glands is the grey line, which divides the inner (close to the eye), and outer portions of the lid margin.

Acute inflammation of a lash follicle is called a “Stye” (hordeolum exter num). It is a reddened, sore lump near the lid margin. Further from the lid margin, chronic inflammation may involve a meibomian gland producing a chalazion.

Blepharitis is the term applied to diffuse inflammation of the lid margin, which is usually the result of an overgrowth of the normal bacterial population of the lid. Patients with Blepharitis have reddened, crusted lid margins usually covering the entire extent of the lid.

The eyelids are composed of an outer layer of skin, an inner layer of palpebral conjunctiva and a layer of fibrous tissue and muscle between the two. The fibrous layer, called the “Tarsal Plate”, gives the lid its firmness. The orbicularis oculi is circular muscle that, upon contraction, results in forced eyelid closure, as in winking. The upper lid is raised by the levator plpebral superioris muscle, which attaches to the upper tarsal plate. The muscle is part of a group of extraocular muscels those are controlled by the third cranial (oculomotor) nerve.

Instead of lying in its normal position against the eyeball, the lid margin may turn away from or towards the globe. This turning out of the margin is called “Ectropion” and may lead to drying and irritation of the exposed cornea and conjunctiva.

An inward turning of the lid margin is called “Entropion”, in this condition, eye lashes may rub against the cornea and cause irritation and tearing, Inward turning of eye lashes is known as “Trichiasis”.

Loss of function of the levator muscle results in “Ptosis” a droopy upper eyelid that no longer elevates normally.

Diseases which affect the skin elsewhere on the body, may affect the skin of the lids. Careful examination may reveal dermatitis, cysts or tumours (especially basal cell carcinomas).

The conjunctiva is the translucent mucous membrane that lines the inner surface of the lids (the palpebral portion of the conjunctiva).

The bulbar conjunctiva ends at the limbus. The junction of the bulbar conjunctiva and the palpebral conjunctiva is called the “Fornix” or “Cul-de-Sac”.

The conjunctiva may become inflamed, due to bacterial or viral infection or because of an allergic reaction, is called “Conjunctivitis”, it is sometimes called “Red-Eye”, produces enlargement of surface blood vessels, causing the normally white part of the eye, the “Sclera”, to appear red. Sometimes, a blood vessel may rapture spontaneously and allow blood to flow under the conjunctiva. This is referred to as a “Subconjunctival haemorrhage and usually resolves in a few weeks without any treatment. Most often this haemorrhage occurs without explanation or after violent s sneezing or coughing, but rarely it may be associated with high blood pressure or bleeding disorders. A pingueculum, a yellowish mass on the bulbar conjunctiva just nasal or temporal to the limbus, probably represents irritation from sunlight. Continued irritation, especially by exposure to intense sunlight, may lead to formation of a pterygium, a fleshy wedge of bulbar conjunctiva that grows from the canthus (usually medial) towards the cornea. It may cause some irritation, but is not harmful unless it grows over the central cornea and impairs vision. If this happens, it must be surgically removed.

Lacrimal Apparatus (Fig. 1.2)

The lacrimal apparatus is composed of tear-producing glands and a tear drainage system. The lacrimal gland secretes the aqueous portion of tears and is located in the lateral segment of the upper lid just under the upper orbital rim. There are small, accessory lacrimal glands scattered throughout the upper fornix. The tear fluid is spread over the front surface of the eye when the upper lid closes during a blink. Tears then form a pool along both lid margins before passing through the upper and lower puncta (holes) into the canaliculi (little canals) of the drainage system. The upper and lower canaliculi merge into the common canliculus near the medial canthus, and the tears then flow into the lacrimal sac. The sac empties into the nasal cavity by means of the nasolacrimal duct. Where hot air being breathed out evaporates these tears.

The tear film is composed of three layers. The meibomian glands secrete the outer, oily layer, which helps prevent evaporation of the tears. The middle, aqueous (water) layer, secreted by the lacrimal gland,

contains the oxygen and nutrients that nourish the cornea. The inner, mucinous layer is secreted by the goblet cells of the conjunctiva. The mucinous layer helps to maintain an even spread of tears over the cornea. The lacrimal system produces up to 1 ml (about 1/4th teaspoon) of tears during the waking hours, about 50% of which are lost to evaporation. No tears are produced during sleep. The tear-producing lacrimal gland is generally free of disease, but occasionally inflammation or tumours may occur in it. On the other hand, inflammation of the tear-collecting lacrimal sac, dacryocystits is relatively common. It usually occurs as a result of obstruction of the nasolacrimal duct. In infants, this obstruction is commonly the result of a congenital narrowing of the nasolacrimal duct where it opens into the nasal cavity. This often opens with time, if it does not it may require probing or other treatment. The signs of dacryocystitis are tenderness and swelling below the inner canthus, discharge or excessive tearing (epiphora). In the adult, obstruction of the tear outflow system occurs as a result of chronic lacrimal sac infection, facial trauma or tumours. If the blockage is severe, it may be necessary to bypass the nasolacrimal duct by surgically fashioning an opening between the sac and the nose (is called”Dacryocystorhinostomy”). Older persons and persons certain systemic diseases, may be subject to dry eyes (keratitis sicca). When one or more of the tear film components is insufficient, the tears cannot function properly and cornea becomes irritated. Patients usually treated with artificial tears.

Orbit

The orbit is the cavity in the skull, which houses the eyeball. Its walls consist of seven bones, and it contains the eyeball, the extraocular muscles, blood vessels and nerves cushioned by a great deal of fat.

Four of the muscles form the muscle cone within the orbit through which pass the optic nerve and most of the blood vessels and nerves to the eye. The muscle cone originates in the posterior orbit as a circle of muscles called “Annulus of Zinn”.

Since the back of the orbit narrows, any increase in the orbital volume will cause the eyeball to protrude; this condition is called “Proptosis or Exophthalmos”. Proptosis is often seen in association with Graves’ disease, a condition of unknown cause that affects both the thyroid gland and the soft tissues around the eyes. Other causes include tumours, inflammation (including infection) or haemorrhage.

Diffuse infection of orbital tissue or orbital cellulitis, appears as grossly swollen lids, a red eye and sometimes proptosis. When the tissue bulk in the orbit is greater than normal, the eye muscles may not be free to move normally. If the eyes go out of alignment (strabismus), the patient may complain of double vision (diplopia). Misalignment of the eyes also results when one (or more) of the eye muscles become restricted in its movement because it has become inelastic from scarring or trapped by broken orbital bones. Muscle scarring occurs after any long-term inflammation, but the most common cause is Graves’ disease.

Extraocular Muscles (Fig. 1.3)

The eyeball is moved by the action of six extraocular muscles. The medial rectus pulls the eye towards the nose in adduction and inserts on the globe 5.5 mm from the medial limbus. The lateral rectus moves the eye away from the nose in abduction and inserts about 7 mm from the lateral limbus. The eye is elevated primarily by the superior rectus (insertion at 8 mm) and depressed primarily by the inferior rectus (insertion at 6 mm). The oblique muscles insert behind the equator of the globe and assist in elevation (inferior oblique) and depression (superior oblique).

The superior oblique also intorts the eye and the inferior extorts the eye. To understand intorsion and extorsion, imagine that the eye rotates on a pole piercing it from front to back. Intorsion means clockwise rotation of the right eye, counter-clockwise rotation of the left eye; extortion is rotation in the opposite direction.

The function of the six extraocular muscles are evaluated by asking the patient to move his eyes from straight ahead gaze, i.e. primary position in to upward gaze, downward gaze and into the six cardinal positions of gaze, which are right gaze, left gaze, up and right gaze, down and right gaze, up and left gaze, down and left gaze. The movement of the two eyes into this diagnostic gaze positions are called “Versions”.

The Eye

The main components of the eye are the

Cornea Sclera Anterior chamber Uveal tract Pupil Lens

Vitreous Retina Optic disc

Cornea

The cornea is the transparent anterior structure of the globe. Its transparency results from a highly ordered cell structure and low water content. The cornea loses its transparency if either of these factors is altered.

There are five layers of the corneal tissue, but the outermost and innermost layers are most important. The outermost layer is called the “Epithelium” which consists of cells that are constantly regenerating.

A superficial injury to this layer, by a contact lens or small foreign bodies, will usually heal within 24 to 48 hours. But infections with viruses, bacteria or fungi will require vigorous medical treatment. The innermost layer, the “Endothelium”, prevents the intraocular fluid from penetrating the cornea. If disease or trauma has damaged the endothelial cells, they may no longer be able to regulate the amount of water that reaches the internal tissue of the cornea. When this occurs, the cornea swells and becomes cloudy, this condition is called “Edema”.

Situated between the outermost epithelium and the innermost endothelium are three layers, called “Bowman’s Membrane”, the “Stroma” and “Descemet’s Membrane”. They each add rigidity to the cornea and provide additional barriers to infection.

The front surface of the cornea focuses light rays and contributes about two-thirds of the optical power of the eye. Because it must remain clear, the cornea contains no blood vessels. The cells are nourished by the aqueous humour and by the tear film, which also serves to maintain a smooth optical surface. The cornea is about 11.5 mm in diameter and 0.5 mm thick at its centre. Its junction with the sclera is called the “Limbus”. The limbus is also the location of the attachment of the bulbar conjunctiva to the globe. Tiny conjunctival capillaries at the limbus supply nutrients to the peripheral cornea.

Corneal inflammation is referred to as “Keratitis” and may result from a great variety of conditions such as a tear deficiency, toxic chemicals or infections. With any keratitis the patient usually experiences a foreign body sensation, eye pain aggravated by bright light, the condition called ”Photophobia”, blurred vision, redness and excessive tearing. In severe cases of keratitis, the anterior corneal tissue is destroyed and a corneal

ulcer develops. Bacterial ulcers may be mild or severe, but the reaction to them is striking. The bulbar conjunctiva, which covers the white of the eye, becomes quite red, and there is often a copious discharge from the eye.

The active ulcer produces an opaque area on the cornea. As it heals, it leaves a scar that may result in permanently decreased vision. The surface of the ulcer must be scraped and cultured in order to discover the specific causative organism, which is treated with the appropriate antibiotic. Fungi may also cause corneal ulcers, usually as a result of a corneal injury with some type of vegetable matter (thorns, branches, pieces of wood). Without adequate treatment, the ulcers may extend through the cornea and cause infection inside the globe.

Herpes simplex keratitis caused by the virus responsible for “cold sores” produces branch-like (“dendritic”) erosion of the corneal epithelium that may progress to form an ulcer. Symptoms of an early infection are often mild, but careful examination reveals that the eye is red and watery. This ulcer must be treated promptly with special anti-viral drugs to prevent spreading to deeper corneal tissues. Once the disease has spread beneath the epithelium, the scar that remains after the healing process may seriously impair vision and leave a total corneal opacity, which may require corneal transplant surgery.

Corneal dystrophies are hereditary defects in the structure of cornea due to which the cornea loses its clarity. Corneal dystrophies become apparent at all ages. One example is keratoconus, in which the central cornea becomes thin and cone-shaped. The increase in corneal curvature at the centre of the cone causes an increasing nearsightedness (myopia) and astigmatism. The process begins in the teenage years and is usually completed by the late twenties. The decreased vision may be corrected in early stages by Rigid Gas Permeable Contact Lenses, but corneal thinning may become severe enough to require a corneal transplant.

A common change in the cornea of older patients is an opaque ring, called “Arcus Senilis”, seen near the limbus. It represents deposition of fatty substances from the blood. While it causes no symptoms, it may be a signal of an abnormally high fat content of the blood.

Sclera

The sclera, the white of the eye, is the rigid outer portion of the wall of the eye that protects and supports the delicate inner structures. The sclera meets the cornea at the limbus. Occasionally the sclera or

overlaying episcleral tissue becomes inflamed (scleritis and episcleritis) and may require treatment. Patients with rheumatoid arthritis may develop areas of marked sclera thinning (scleromalacia) which allows the purple colour of the underlying choroid to show through.

Anterior Chamber

The anterior chamber is the space between the back of the cornea and the front of the iris. It is filled with clear aqueous fluid humour produced by the ciliary body lying behind the iris.

The aqueous fluid is secreted by the processes of the ciliary body and flows through the pupil into the anterior chamber. It exits from the eye at the junction of the cornea and the iris, where it flows through a filter called the “Trabecular Meshwork” and into the canal of “Schlemm”. From here it empties into episcleral veins.

The balance between aqueous production and drainage normally maintains the intraocular pressure between 12 and 20 mm Hg (mercury). If aqueous drainage is impaired, the intraocular pressure rises and may cause optic nerve damage and loss of vision, this condition is called “Glaucoma”.

Inflammation or infection within the eye may cause a pool of pus (hypopyon) to layer out at the bottom of the anterior chamber. When blood is found in the anterior chamber, after an injury or in certain diseases, it is called “Hyphema”.

Uvea

The uvea or “uveal tract” is the middle layer of the wall of the eye and is composed of the iris, the ciliary body and the choroid. The iris is the coloured part of the eye that controls the size of the central opening, the “Pupil”. The front layers of the iris contain its blood supply, muscles and pigment. The dialator muscle, which extends radially from the iris root to the pupil margin, opens the pupil (mydriasis) when it contracts.

The sphincter muscle encircles the pupil margin and makes the pupil smaller (miosis) when it contracts. A blue iris contains a relatively small amount of pigment while brown iris contains a relatively large amount. Pigment is deposited in the iris as the nervous system is developing. Because some of this development occurs after birth, most newborn babies have light eyes. Since the appearance of the net of new blood vessels on the iris gives it reddish cast, it is called “Rubeosis. Rubeosis may be responsible for blood leakage into the anterior chamber or obstruction of the filtration angle. Several diseases (especially diabetes)

may cause an abnormal growth of new blood vessels (neovascularisation) on the surface of the iris. The iris may also be the site of nevi (freckles), tumours, cysts or nodules. The ciliary body is a band-like structure of muscle and secretory tissue that encircles the inside of the eye from behind the root of the iris to the anterior edge of the retina (the ora serrata). Most of the function of the ciliary body is concentrated in the anterior part, a folded muscle mass called the “Pars Pilicata”, which is composed of finger like ciliary processes that are responsible for secretion of the aqueous fluid. The posterior portion of the ciliary body is flat and is called the “Pars Plana. This latter area is a frequent site for surgical entry into the back of the eye because it contains relatively few delicate structures. Some of the muscle fibers of the ciliary body are arranged in a circular fashion and these control the eye’s ability to focus on near objects (the phenomenon is called “accommodation”).

The ciliary body may become inflamed in diseases that affect the iris and choroid as well (uveitis), it may also give rise to tumours or cysts.

The choroid is the posterior portion of the uveal tract. It is largely composed of blood vessels and lies between the sclera and the retina. It provides the blood supply for the outer cells of the retina. Inflammation of the choroid (choroiditis, posterior uveitis), may result from infection or from unknown (idiopathic) causes. The choroid may be the site of tumours such as malignant melanoma or metastatic cancer. Malignant melanoma is recognised as an elevated pigmented lesion that may cause the retina to detach. It is important to diagnose malignant melanomas early, so they can be treated before they spread to the rest of the body and cause death.

Pupil

The pupil is the central opening in the iris that regulates the amount of light reaching the retina. The size of the pupil is controlled by the sphincter and dilator muscles of the iris. Each of these muscles is governed by a different part of the autonomic nervous system.

The sympathetic system controls the dilator muscle that opens the pupil and the parasympathetic system controls the sphincter muscle that closes the pupil. Ordinarily the pupils are about 4 mm in diameter in a dimly illuminated environment and equal in size in both eyes. It is not unusual for the pupil sizes, in an individual, to differ, from o.5 to 1.0 mm. When the two pupils of an individual differ in size by more than 1.0 mm (anisocoria), there is an abnormality of one pupil or other (or both). If the

inequality is greater in dim illumination where the pupils usually larger, then the dilator muscle is not working in the eye with the smaller pupil. On the other hand, if the anisocoria is greater in bright light, when the pupils are usually smaller, then the sphincter is not working in the eye with the larger pupil. Once the weak muscle has been determined, the part of the nervous system that is affected can be identified.

Lens

The crystalline lens is a normally transparent, biconvex structure that is located in the posterior chamber between the iris and the vitreous body. The lens is composed of an inner nucleus, a surrounding cortex and an enveloping capsule.

The lens is responsible for about 1/3rd of the total focussing power of the eye and accounts for the ability to change focus from distance to near objects. The lens is suspended just behind the pupil by fibers called “Zonules” that are attached to the ciliary processes. When the ciliary muscles muscle contract, it relaxes the tension on the zonuls and allows the lens to become more round. The increased curvature of the lens makes it a more powerful refracting surface.

The process of ciliary muscle contraction and increased lens curvature is called accommodation. The ability of the lens to change its shape depends on its elasticity. As it ages, the lens tissue becomes increasingly more rigid and accommodation power is gradually lost (presbyopia). This is the reason that most people, as they age, have to wear corrective bifocal spectacles; the lower segment helps the eye focus on near objects.

When the lens proteins degenerate, the lens loses its transparency, this is called a “Cataract”. Thus synonyms for cataract are lens opacification. Cataracts may be present at birth, though this is rare. Most commonly, cataracts occur as part of the normal aging process (senile cataract). Lens opacities may also be the result of an injury to the eye or may be associated with ocular or systemic disease or with chronic use of certain drugs. When vision has become significantly impaired, the lens is surgically removed. An eye with a lens in place is called “Phakic”. Once the lens has been removed, the eye becomes “Aphakic”. When the eye’s own lens has been removed, its refractive power must be replaced with a powerful artificial lens, either as a spectacle, a contact lens or an intraocular lens (implant).

Vitreous

The vitreous body is a clear, gelatinous mass that fills the intraocular cavity behind the lens and helps maintain the spherical shape of the globe. When small particles drift across the vitreous, patients report that they see floaters. Floaters are a normal occurrence and need not be investigated unless they suddenly increase in number, if so, they may represent condensations of a portion of vitreous that has become detached from the retina. This vitreous detachment occurs as a normal part of aging, but may lead, in rare cases, to a retinal detachment, a vision threatening emergency.

The vitreous material is an excellent culture medium for bacteria. When infectious agents are accidentally introduced into the eye, either by injury or surgery, their growth may be so rapid as to destroy an eye within days. Infection of the vitreous and the adjacent tissue is called “Endophthalmitis” and constitutes an emergency. The infection is treated with large doses of antibiotics, but may also require the surgical removal of the infected vitreous (vitrectomy).

Abnormal retinal blood vessels may produce a haemorrhage into the vitreous that obscures vision. Usually this blood is absorbed over time. However, if the blood or resulting fibrous tissue remains, the vitreous may have to be removed surgically.

Retina

The retina is a transparent structure that lines the inner surface of the globe posteriorly, and is actually an extension of the brain. It converts light to electrical (nerve) impulses and transmits these impulses to the brain’s visual cortex where they are integrated into the sensation of sight. When viewed through an ophthalmoscope, the normal retina appears orange, the retina though transparent, appears orange due to the blood vessels of the underlying choroid. Lying on the inner surface of the retina are the retinal arterioles (bright red) and veins (dark red).

The retina is composed of an inner sensory portion and an outer pigment epithelium. The most important part of the sensory retina is the photoreceptor layer. It contains two types of photoreceptor cells, the cones and the rods, each with a different function in the visual process. Cones provide sharp central vision (acuity) and colour vision and function best in daylight. Rods are largely responsible for peripheral vision and function even in dim illumination. The innermost part of the retina consists of ganglion cells. Fibres from the ganglion cells for m the nerve fibre layer of the retina that converges at the optic disc. A

specialised area of the retina containing most of the cone cells is located lateral to the optic disc and is called the “Macula”. The centre of the macula is called the “Fovea”. Damage to the macula will greatly reduce visual acuity and the eye will be left with only peripheral vision. When any other area of the retina is damaged, blind spots occur in off-centre position of the visual field. During development of the embryo, a cleft forms between the sensory and pigment epithelial portions of the retina that, under certain circumstances, may lead to an actual separation of these layers. Such a separation is called a “Retinal Detachment”. Trauma inflammation, eye surgery or the natural aging process may result in a tear in the sensory retina. Vitreous fluid leaks through the tear and spreads under the sensory retina causing it to become detached from the pigment epithelium. Patients who have a retinal detachment notice floaters, light flashes, blurred vision and sometimes the sensation of a “curtain” obscuring a portion of their field of vision. The detachment must be repaired surgically as soon as possible to prevent irreparable damage to sight.

Of the many disorders that affect the retina, senile macular degeneration is probably the most common. It occurs in the elderly and produces a slow decline in visual acuity usually in both eyes. The cause appears to be poor choroidal blood supply. In this condition, abnormal blood vessels (neovascularisation) that form beneath the macula leak and deform this delicate structure. In some cases such neovascularisation may be treated with the laser beam to prevent further vision loss.

A rare tumour called a “Retinoblastoma” can arise in the retina of very young children. Because retinoblastoma is life threatening, the eye containing this tumour is treated promptly, either by radiation or surgical removal (enucleation).

Optic Disc

After passing through the transparent inner layers of the retina, light is converted by the rods and cones to a nerve impulse that travels forward to the ganglion cell layer and then to the optic disc by way of the nerve fiber layer. The optic disc is situated in the nasal portion of the fundus, 15 degrees off-centre. Because no rods and cones are present in this area, it is sightless and termed the physiologic blind spot in the field of vision. Inflammation and stroke (blood vessel blockage) can damage the optic disc and produce defects in any portion of the field of vision. When the intracranial pressure is abnormally high, the disc tissue will swell (papilledema). There are other causes of optic disc swelling, including

inflammations and strokes of the disc tissue itself. The optic disc tissue becomes excavated (cupped) in advanced glaucoma.

Retrobulbar Visual Pathway (fig. 1.4)

The eye is only the first part of the visual pathway, which extends to the back of the brain. The pathway that conducts visual messages after they leave the eye is termed the retrobulbar visual pathway.

The nerve impulse triggered by light striking the retina exits from the eye through the optic nerve, travelling to the optic chiasma. Here only the nasal nerve fibres from each eye cross to the opposite side, while the temporal fibres continue along on the same side. After the chiasma, the temporal nerve fibres from one eye and the nasal fibres from the other eye travel together in the optic tract and end in the lateral geniculate body.

From there the impulse is carried via the optic radiations to the occipital lobe in the posterior part of the brain. The destination of these fibres within the occipital lobe is called the “Visual (calcarine) Cortex”, where the visual message is integrated with information derived from other parts of the brain in a process called “Perception”.

Disorders affecting other parts of the visual pathway produce characteristic changes in the field of vision. The most common disorders are tumours of the pituitary gland (which lies directly under the chiasma) and strokes, aneurysms, inflammations, infections and trauma.

3 OCULAR TRAUMA

Permanent disfigurement can occur following ocular trauma. The different types of ocular trauma are:

Foreign body in the eye, that may leave permanent corneal opacity,

Chemical trauma can cause total corneal opacity and many complications in the eye such as symblepharon, phthisical eye etc.

Blunt trauma can lead to permanent loss of vision due to retinal detachment and may further lead to pthisisbulbi.

Penetrating injury in the eye can result in retinal tear, infection leading to evisceration or enucleation of the eyeball.

Blow out fracture of the orbit because of the accident can lead to severe disfigurement.

Surgical trauma means failure of surgical procedure on the table or iatrogenic trauma due to post surgical infection can lead to evisceration or enucleation of the eyeball.

4 REMOVAL OF AN EYE (enucleation)

When a Doctor advises an eye removal the patients always get shocked and worries about what the operation involves and their appearance after the eye removal. These are normal reactions and I hope that the information below will help to answer some of these anxieties.

Reasons for Removal of an Eye

The eye needs removal because

It is blind and painful. It has developed some Tumours (malignant). After a severe injury.

The answer is that an eye removing operation is not recommended lightly and undertaken only when all other treatments are ineffective, inappropriate or undesirable.

It is the final measure, taken in the best interest of the patient, by the Ophthalmologist (an eye doctor) after a great deal of consideration and consultation with patients, parents and if required with other Ophthalmologists.

Removal of an Eye

Patient is usually admitted to the hospital one day before the surgery for tests to check their health because the operation involves having a general anaesthetic. General anaesthetic is administered to the patient for this operation so the patient will be asleep during the procedure that takes about an hour.

Before the operation the patient will be asked to sign a consent form for this surgery which is a necessary.

Enucleation is the surgical removal of the globe (eyeball) only. The eyelids, brow and surrounding skin are all left intact.

The eyeball is removed by incising and preserving the conjunctiva and detaching the muscles from the eyeball, the optic nerve is severed.

An implant such as a plastic ball, Hydroxyapatite ball or Medpore ball may be sutured into the socket (space left by the eyeball), the muscles are re-attached around this and then it is covered with conjunctiva (the mucous membrane which lines the inner surface of the eyelids and stretches over the white part of the eye and the cornea, the coloured part of the eye), which is sutured together over the implant to give the socket a moist and pink look. A conformer (a clear plastic shell) is put in place behind the lids. This gives some shape while the socket heals. The operated eye will be covered with a pressure pad and dressing for 12 to 48 hours. During this time the patient may experience difficulty in opening the lids of the un-operated eye. This can be frightening because it means that the patient may not be able to see at all, but it only lasts while the pad is in its place. The pad is intended to reduce swelling of the tissue in the socket. As the anaesthetic wears off the patient may feel some pain in the socket or have some sickness that can be relieved with medicine. Normal activities can be resumed as soon as the patient feels fit for it.

When the eye pad is removed, the nurse caring for you will clean your lids and the Ophthalmologist will examine the patient’s eye socket with a torch and prescribe eye drops or ointment.

The eyelids may be swollen and bruised for a few days. The patient may be asked to use dark glasses till the swelling subsides. The socket is left unpadded to promote healing.

Initially when the patient opens eyelids the patient may see the moist, pink socket lined with conjunctiva. If there is a conformer (shell) in place the patient will see the clear plastic with a hole in the centre. The shell is only there temporarily until the socket heals and stock artificial eye or a custom-made artificial eye can be fitted. Usually it takes six weeks before the custom-made artificial eye can be fitted.

Medication

In case of the patient being a child of less than two years age. Only enucleation is performed and non absorbable sutures are placed on the four rectus muscles so that they can be identified afterwards for putting the motility implant when the child is a little older.

Aftercare

Patients are taught, by the nursing staff, to look after themselves and the eye as soon as possible. Patients are advised to stay in the hospital till they are confident that they can take care of themselves, usually a few days. In some circumstances, family and friends are taught, so that they can help the patient.

Initially the patient may need to clean the lids with cool, boiled water to remove any mucous. If this mucous becomes excessive or discoloured the patient should see the Ophthalmologist.

Hands should always be washed thoroughly before touching the operated area and it is advisable not to touch the socket. The patient may need to wash the shell, initially twice a day with soap and water. Rinsing thoroughly to ensure that no soap remains on the shell and replace it. Patient can wash the face normally.

If the shell falls out on its own, which is rare, clean it thoroughly with soap and water and rinse it thoroughly before replacing it.

For the first few weeks the patient has to put eye drops to prevent infection. The patient need not remove the shell or artificial eye to instil eye drops or ointment.

Ophthalmologist refers the patient to an Ocularist for fitting of artificial eye.

The Ocularist will decide when to give a custom-made prosthesis. This involves the moulding of patients eye socket using impression material (a painless procedure) and hand painting of the eye colour. The eye shape, size and colour are made to match the good eye so that it is difficult to tell them apart.

There should be an adequate range of eye movements of the artificial eye if it is custom made. The prosthesis can be worn without removing for days together. It can be worn during sleeping hours as well. The discharge is reduced if it is custom-made artificial eye (prosthesis).

The patient can wear eye make-up once the socket is healed completely.

Patient is advised to wear goggles when swimming and remove the artificial eye if diving or water skiing to prevent loss.

It is necessary to wear protective goggles when doing anything that may cause injury to the remaining good eye.

5 TYPES OF PROSTHESIS

Different types of Ocular Prosthesis are used to treat different problems.

For simple corneal opacities instead of doing tattooing one can use cosmetic contact lens. Opacity away from the visual axis of the cornea can be hidden behind the prosthetic lens with a clear pupil. This lens can be powered for any refractive correction for the seeing-eye.

If the corneal opacity is big or on the central cornea (pupil) then iris painted with a black pupil prosthetic is used.

On occasions the non-seeing eye, over a period of time, becomes divergent. In such cases off-centred prosthetic lens can be used.

Where the cornea is irregular a soft or hard lens cannot be fitted then a Sclera lens or a Cosmetic shell has to be considered.

In a situation where the size of the eyeball has shrunk (phthisical eyeball) one has to use a Cosmetic shell.

If the eye is eviscerated or enucleated one has to use an Artificial Eye.

Difference between an Artificial Eye and a Cosmetic Shell is that the former is thicker than 2.5 mm.

Many countries do not have a trained Ocularist so they are forced to depend on stock eyes which are prefabricated. Though they are cheap and readily available, they often do not match the natural eye and tend to cause discharge and discomfort. In the long run they cause lower lid sagging. They also restrict movement and wearing period.

In some cases, a stage is arrived at, where no artificial eye can fit the socket, it just pops out as the lower fornics get inverted or a mass of tissue grows in the hollow cavity of the stock eye, which push out the prosthesis on upward guise. The socket can get contracted as well.

To solve these entire problems one should always use custom-made Artificial Eyes or Shells as the look more natural and greater movement with comfort and prolonged wearing periods.

A significant advantage is that custom eyes and shells give much less secretion the patient feels more comfortable and forgets the problems created by an uncomfortable eye or shell. As a result the patients become more confident interacting with other people in the society.

An additional advantage of custom-made Eyes and Shells is that modifications can be made to the prosthesis in order to develop or expand the contracted socket; depth of the cul-de-sac can be expanded with special edge design.

Some special design can reduce the effect of ptosis. A notch can be developed on the Artificial Eye surface for correcting a severe ptosis.

For the divergent non seeing-eye correctly painted iris avoids surgery and gives a normal look. It places less or no weight on the delicate lower lid.

Patients can wear the custom-made prosthesis even during sleeping hours without having to remove it for many days.

For a totally exenterated eye one has to give a facial prosthesis to be mounted on spectacles. Magnetic implant can hold the prosthesis in place if an iron sheet is placed inside the prosthesis.

For natural eye movements intra orbital implant of Hydroxyapatite or Medopore can be drilled in the ball and socket type or direct attachment can be made to the Artificial Eye to achieve more natural eye movements.

6 FACIAL PROSTHESIS

Facial Prosthesis (fig. 6.1) or external prosthesis is used for the patients with exenterated eye. It can be made of silicone rubber or hard acrylic.

The life of silicone prosthesis is about 2 years, whereas acrylic prosthesis can last for about 10 to 15 years.

The external prosthesis needs to be attached to spectacles or a magnetic implant can hold the external prosthesis at the given position.

The patient needs to get his spectacles, with the prescription, if any, for the seeing- eye. The same prescription has to be incorporated, in the frame, on the non-seeing side. The cylindrical power in the seeing-eye, should also be kept on the non-seeing side. If the axis are 90 or 180 then there is no problem keeping the same power on the non-seeing eye. But if it is not 90 or 180 then the axis needs to be transposed i.e. add or subtract 90 degrees from the axis that will give you the correct magnification on the non-seeing eye.

Impression of the patients face is taken with alginate, while alginate is setting; fast setting plaster gauze is placed on the alginate which will give required stiffness to the impression.

Using this impression a cast is made out of this and using base plate dental wax is sculpted the eye and other portions surrounding the eye.

The eye has to be custom-made beforehand to match the iris and the sclera etc.

Using this eye the facial prosthesis is sculpted. The eye plane position and protrusion are considered while sculpting the prosthesis.

Once satisfied with the wax sculpting a plaster mould is made and pink acrylic is cast out this the position of the eye is cut off from the back side and the custom-made eye is put in its place and sealed with self curing acrylic.

Artificial eyelashes are used and painting of the prosthesis is done with oil colours using chloroform to match the patient’s skin shade.

This prosthesis is attached to the spectacle permanently or using a wire attachment.

7 VISION WITH ONE EYE

Vision is the most important sense out of the five senses that we possess.

Light coming from the surrounding objects is perceived through the eye and is converged on to the retina after travelling through the cornea, the aqueous humour, the crystalline lens and the vitreous humour.

Millions of retinal cells of rods and cones convert these photons of light into signals through the nerves by reversible chemical reactions and the signals are carried to the brain’s occipital cortex and are analysed, stored, evaluated and based on previous experiences necessary action is taken by the brain.

Seeing

Seeing is a learning skill, our vision develops as we grow. Since birth till the age of 4 to 5 years growth is faster and during this period one learns to see. It takes an educated brain to understand and evaluate the given images.

Every individual is right-eyed or left-eyed. Depending on which side of the brain is dominant, the individual becomes a righty or lefty.

In general right side of the body is controlled by the left hemisphere of the brain, and vice versa. Therefore in the case of the eye it is the image falling on the right side of the retina of both eyes are sensed at left occipital cortex and vice versa. Hence loss of right eye in a righty individual makes the situation more difficult than in a lefty individual.

There are other factors that affect the readjustment after the loss of an eye, visual acuity of the surviving eye and the structure of the society and surrounding.

Age is also an important factor in getting used to the new one eye situation.

If the patient is one eyed since birth the patient will have less difficulty in moving around as the patient’s brain has learnt by taking information from one eye only. However, if the patient has lost an eye afterwards it takes a long time to learn the new situation. The loss of vision may be gradual or sudden also makes a difference. In case it is gradual, patients also learn gradually to adapt but if it is a sudden loss of vision it more difficult to adapt with one-eyed vision. It may take as long as a year to re-educate the brain. If, on the other hand, the patient understands the mechanism of seeing and learns how to readjust the patient can get back their confidence very quickly. The patient’s psychological state of mind also has bearing on adaptation period.

When one eye is lost the person’s horizontal field of vision becomes narrow. The depth of perception is impaired and the whole visual system including the brain is in disarray and in need of many adjustments and re-education.

Mechanism of seeing (fig. 7.1)

We live in a three dimensional world hence our seeing has a lot of information coming from all the dimensions.

Our brain understands objects by their size, shape, colour, shadow and its relativity to other objects and previous experiences.

When a distant object is seen the visual axis are practically parallel, the object forms an image upon each fovea (retina). Other objects to one side, i.e. either on the left or right will form their images on the opposite side. An object on the right will form its retinal image on the temporal side of one retina and an object on the left will form its image upon the

nasal side. These retinal areas are coordinated visually in the occipital cortex so that an object seen with both eyes is seen as a single object. The image of the right side falls on the lateral side of the left eye and nasal side of the right eye. In the same way the image of the left side falls on the nasal side of the right eye. Optic nerves cross at the optic chiasma and image on the right is sensed at the left occipital cortex and left side image is sensed at right occipital cortex.

In case of eyes the information is received by two different angles and these two images are superimposed on each other in the brain.

When Sachin Tendulkar swings at a pitched ball, his body moves in intricate balance, responding to a complex set of orders initiated by the eye. Visual messages trigger a chain reaction that coordinates muscles and brain. Signals from the eye speed along the optic nerves to the visual cortex. Some of these impulses reach the motor cortex and frontal association cortex and are swiftly relayed to the spinal cord. The spinal cord in turn sends messages to the muscles, setting the body in practices, well coordinated motion.

Field of Vision (figs. 7.2 & 7.3)

The normal field of vision is 180 degrees, with one eye it is about 140 to 160 degrees and one eye’s field of vision superimposes the blind spot of the other eye thus achieving 180 degrees field of vision. With the loss of one eye one has only 140 to 160 degrees of field available and hence one has to use one’s head movements to compensate the field loss.

Depth Perception (fig. 7.4)

Depth perception requires understanding the size and distance of an object. It is a complex procedure that involves psychological factors and accommodation-convergence ratio.

Each eye sees an object with a slightly different angle and the brain makes use of this information to understand its size and the angle of convergence and the amount of accommodation provides the distance sense. Since the two eyes have to converge on the same object to view it, the closer the object greater the angle of convergence, this information is used for computing the distance. When the object is more than 6 meters away the eyes do not converge so this information is not of much value. At the same time, at this distance, the details of the object are less obvious.

Eye is at rest when focussing at a distance of more than 6 meters, when one has to view closer objects, the crystalline lens of the eye changes its

dimensions to increase its focal length to bring the object into sharp focus on the retina; this phenomenon is known as “Accommodation”. Now the amount of accommodation is greater when viewing closer objects. To focus an object at 1 meter distance the eye has to increase the dioptric power to increase to 2 Diopters and so on. This information is used by the brain to compute the distance of an object.

For the one eyed convergence is of no value but accommodation information is used for depth perception along with the size, shape, colour, shadow and brightness of the object as well as previous experiences.

Action after seeing

The relationship between eyes, brain and body has developed since birth. Seeing is only part of visual process that involves all other elements of the system to respond to reactions between all these elements with amazing swiftness and sensitivity.

When you read, your brain consults its vast memory bank in order to make a judgement about it. It tries to analyse the information received and it is stored for further use or reference, in respective areas of the brain. If required action is taken depending on the situation, e.g. you turn the page, as your brain sends the commands via the nervous system to activate the body’s motor system, and your fingers obey the order to turn the page.

When the brain receives an impaired or different visual message you see illusions. When you have no past experience about the subject of the message, say due to loss of one eye, the message received by the brain is not fully analysed and you make mistakes. Hence, one has to re-educate the brain for one eyed-vision.

Re-Educating the Brain

A photograph is a two-dimensional picture, somewhat similar image is perceived with one eye. When one eye is lost you do not see a little to the right and left due to reduced field of vision. So far, the other, the lost eye, was compensating for that, and providing 180 degrees of the field of vision. Secondly, with one eye lost, one does not have two slightly different images, with different angles, and there is no convergence of the eye, to see the image. Hence what one sees is flattened-out scene like a photograph.

If you move your head a little, all the surrounding objects will be seen with a different angle, and suddenly they will come to life with three

dimensions again. One’s brain gets the information of relativity that gives the objects their accurate positions and sense of distance from each other.

Relative motion

When one moves one’s head and try to see the same object, what one does is one gets more information about the object due to relative motion of the object against the surrounding.

The relative motion will compensate for binocular vision and help a one-eyed person to come back to normal life.

Knowing this one can readjust to the situation very fast. One can make use of this relative motion in all one’s activities like driving, boating, skiing, skating etc.

Understanding the perspective of the object also help to judge its distance and size-shape i.e. three dimensional image.

If you see a photograph, you can understand that the objects which are closer take up greater area, of the photograph, than the objects, of the same size, at a distance.

Colours also look more bold and bright in the foreground, whereas in the distance they appear softer and muted. Shadows of the near objects appear sharp and dark and distant objects look blurry while a closer object looks sharp.

These observations are important for a one-eyed person. If you know the real size of the objects you can estimate its distance from you.

Tips and suggestions for one-eyed patients

In an everyday life of a one-eyed person many challenges are faced like a hand shake, cooking, dining, travelling by train or bus, driving etc.

Here are some tips to make life easier

For shaking hands bring your hand in line with the other person and then slowly move forward till the hands meet – this is the best way to ensure that the hands do not miss each other.

Whilst cooking, one needs to pour or transfer things to a bowl or utensil. The best way to do this is to touch the bowl or utensil with a spoon or jar

to transfer the contents in order to ensure that contents do not spill on the floor.

Moving your hand horizontally will give you understanding of the surrounding field.

Moving your head, horizontally from side to side, will ensure that you do not collide with people or objects and will make it easy to move around.

While dining one should move one’s head towards the lost eye side before making any gestures on that side.

While climbing or descending, steps or stairs, ensure that you know where the first and the step is. Making sure by using your toe or keeping a hand on the railing will avoid undue accidents.

While crossing the road one should concentrate on the edge of the footpath while moving ahead, this will show the road ahead and allow one to gage the height of the footpath from the road. While crossing the roads one should see both the sides by moving the head in both directions, particularly on the limited peripheral vision side whilst making a move.

Driving a car with one eye is a difficult task. While driving if the car in front of you moves at the same speed as yours it is difficult to judge its distance from you what you should do is to either slightly increase or decrease the speed of your car which will give you the relative motion and you will be able to judge the distance. While coming out from a parking lot you can follow the car in front of you or you can take your passengers help to drive or you can drive close to the line of cars on your right with your head out of the window if found necessary. While parking again you can take your passengers help, or come out of the car and judge the distance between the cars and the situation or select a parking slot where there is plenty of room for parking. Make use of your headlights, even during daytime, to help you judge the distance from other cars while parking. The pattern of the beams will help judge the distance. Selecting a car can also make your life easier. The car that gives you the greater clearer front view, headlamps and reversing lights will of helpful and the smaller the car better the control and easier manoeuvring.

Loss of an eye need not mean an end of all activities in fact one can get back to normal or even better performance in life, in all fields by determination and re-education.

Precautions

With a loss of one eye it becomes of paramount importance to safeguard and protect the surviving eye. Eye specialist or an Optometrist can tell you whether you need prescription glass for the surviving eye. It would be wise to wear eyeglasses that are toughened and are impact resistant. Rimless are to be preferred. Antireflection coating on the glass will be advantageous as it will increase visibility and reduce reflection and ghost images. They are also useful for driving. Having the same prescription for the non-seeing eye will increase the cost but will give a better cosmetic appearance, which is explained in detail the “Cosmetic Optics” chapter. Good lights and lighting and contrast will compensate for impairment in vision.

Taking care of the Good Eye

It is important to give special consideration to safeguard and care for eyesight of the one remaining eye. As the persons future depends on that seeing-eye as, if something should go wrong with the good eye, total blindness will be experienced which, naturally, is unwelcome. Therefore the surviving eye should be well protected. It is a myth that one cannot lead an active life with one seeing-eye; it is a false belief that one should not use one’s good eye too much.

Regular, annual, eye examinations by an Ophthalmologist are advisable. Any new sign, symptoms such as redness, blurred vision, pain, heavy discharge or headache should be immediately reported to your eye doctor.

Even a small change in vision can be disturbing for a one-eyed person. It is necessary to test your eyesight more often and change the glasses with corrected prescription if and when necessary.

Special attention should be paid to situation like injuries, infections, Glaucoma, Cataract, Retinal Detachment, Diabetes, High myopia (explained in detail in other chapters) for which proper medical advice and prompt treatment should be taken to preserve the good eye.

Non-Seeing Eye

If, your eye is enucleated or eviscerated an artificial eye or a cosmetic shell can rehabilitate you cosmetically. If you use a ready-made artificial eye, it will give you a discharge, discomfort, watering and restricted wearing period, artificial look rather than natural, and restricted or no movement. In the long run your lower eyelid will sag due to the weight of the stock eye and you will need surgical correction. To overcome these problems one should use a custom-made artificial eye and if possible a

peggable integrated orbital implant, that will give no weight on the lower lid. This is discussed in the chapter “Ocular Prosthesis” in detail.

Contact Lens

A one-eyed person who needs corrective lenses for the seeing-eye can benefit with the use of contact lens as it gives best corrected visual acuity and widest field of vision.

Good care of the lens under medical supervision is essential. Your eye doctor or an Optometrist can help you understand and advise you of the best contact lens for you.

Cosmesis

Even if you have lost an eye, by cosmetic surgery and using a custom- made eye prosthesis you can look normal, but some defects do remain, like restricted movement at extreme ends or a difference in the two eyes, after all it is artificial. Both eyes may not move in unison, while looking side-ways the artificial eye may lag behind, the best thing to do, to avoid this, is to move your head, rather than just your eyes, while seeing side-ways. When talking to someone face the person and look straight in the eye. This will avoid the other person from knowing that your one eye is not real.

Parenting

Parents of a one-eyed child have to be careful and understand the sensitivity of the subject while talking to the child. If one is not careful and undiplomatic, one can damage the child’s emotional outlook which is more important to the child than the physical loss of an eye.

Any discussion of the loss must be adjusted taking into account the child’s age, sex, emotional stability, maturity, natural coordination and their relationship. Parents should understand the impact of an eye loss and should not exaggerate fears of the loss. Children usually adapt themselves faster to the new circumstances than adults.

You can be reassured and make the child understand that monocularity can set very few limitations and he/she is not the only one in the world with one eye, there are many great people and personalities in the world with one eye.

8 OCULARIST

An Ocularist is a carefully trained technician skilled in the arts of fitting, shaping and painting Ocular Prosthesis. In addition to creating it, the Ocularist shows the patient how to handle and care for the prosthesis and provides long term care through periodic examinations.

There is no school or institute around the world to produce Ocularists. But the art and science of making artificial eye is learnt by observation and supervision of a practicing Ocularist like an apprentice-ship.

To become an Ocularist one should have a good artistic hand and understanding of primary medical and chemical knowledge and a lot of practice.

Every case is different and needs careful consideration and needs to be dealt with separately.

An Ocularist has to deal with a patient who has lost a vital organ of the body are often under psychological trauma. The y needs to be handled gently. One must have a caring attitude towards the patient and should try to put the patient at ease and deal with their tension.

Patients often come with great expectations, one should explain the limitations of the art and science of the Ocular Prosthesis or making of an Artificial Eye, after all it is an artificial item and has to compete with nature. Only God or Nature can make a new live eye. Humans have their limitations in competing with nature. One should try to give their best in making an artificial eye look natural. An Ocularist should explain to patients with singular vision to re-educate themselves, making their rehabilitation faster in society.

All over the world there are around 500 to 600 Ocularists at present. There is a vast need of trained Ocularists to help disfigured eye patients to rehabilitate them cosmetically and socially.

One can get more information on Ocularistry on the internet by visiting the following web site:

www.ccularist.org and www.oculaplastic.com

www.ocularist.co.in

9 A DAY WITH AN OCULARIST

When a patient with one eye visits an Ocularist to get his/her eye custom made, the Ocularist will examine the eye socket and carefully note your history and will explain what he can do and how he proposes to go about it. He will also give you an estimate of cost. The fees cover cost of the prosthesis and your subsequent visits.

He will then give you an appointment. On the day of the appointment, he will take an impression of your socket with alginate which is a painless procedure. He will then make a mould of wax out of the impression taken and will attach an aluminium button to the wax model and this wax mould is tried in the eye socket. He will then position the aluminium button for exact location of the pupil and at the same time he will sculpt the wax model to an exact size, shape and lid closure.

Once the Ocularist is satisfied with the wax model, he will paint a PMMA (poly methyl methacrylate) corneal button by reverse painting technique or he will reproduce the iris colours on iris disc, which then glued to the corneal button.

Iris painting and wax model sculpting may take an hour or so, and then the patient is free for two hours. During this time the Ocularist makes a mould of wax model in stone plaster. Using the plaster mould he will cast a white scleral shade plastic along with iris cornea unit.

The Ocularist will smooth and polish the complete unit and will try it in the eye socket. Once satisfied with the size, shape, location of iris and the lid closure he will cut some portion white plastic and will do some fine painting on iris and will imitate the blood vessels and paint the scleral shade to match the other eye. This may take another hour or so and again the patient free for two hours.

The Ocularist will then process the eye with clear plastic and will smooth and polish it with high precession for the final fit and delivery.

The Ocularist will then teach you how to insert and remove your artificial eye and how to take care of it.

He will clean the prosthesis and fit it in your eye socket and show you in a mirror to see the effect for yourself. If he is satisfied with the work he will give the prosthesis to you if however he feels that he can do some more work on it to make it more natural he will not give you the eye and will give you another appointment for the same.

Many times patients cannot make out the results as they are not used to seeing themselves with a natural looking eye in place of the missing eye. It may take some time for the patient to get used to the new look.

It is advisable to bring along a friend or a relative for the day long ordeal.

When patients come for refitting after using some prosthesis, many times he feels that his old prosthesis looks good, as he/she is used to seeing themselves with it for a long time and it takes a day or so for him/her to appreciate the new artificial eye and the way it looks.

Many Ocularists do the prosthesis in two sittings. In the first visit impression, wax model and iris painting id done and on the second visit sclera painting and delivery is carried out.

10 CARING FOR YOUR OCULAR PROSTHESIS

Whenever a prosthesis is removed from the eye socket it should cleaned using soap and water (liquid soap would be a good idea) and rinsing it thoroughly with water to remove all traces of soap from the prosthesis, if this is not done thoroughly it may cause more discharge. This can turn into a vicious circle.

The more times the patient removes the prosthesis, even just to rinse it, the more secretion there will be. It can take 2 to 3 days to get used to a new prosthesis, before the stability is reached, with little secretion.Frequent removal to rinse the prosthesis increases the production of secretions, which in turn gives one the feeling of having to remove the prosthesis more often

Daily Care

A blinking action, with upper lid moving over the front surface of the prosthesis, will cause it to be cleaned without having to remove it. To keep these areas clean, moisten a clean tissue paper or a clean handkerchief, with warm water and rub lightly, as and when needed.For a thorough cleaning place the prosthesis in a small bowl filled with very hot water (never use boiling water). Leave the prosthesis soaking in the hot water until the sediment (deposits on the prosthesis) has softened, that can take about 15 seconds. With clean soft cotton or clean tissue paper rub the prosthesis vigorously for 30 seconds, then replace the prosthesis in the water and rub again vigorously. If the prosthesis remains dull and rough, repeat the procedure changing hot water 2 or 3 times. A bright light reflecting off the surface of the prosthesis will permit you to identify any remaining deposits.

If your eyelids do not close completely or if you work in an environment with air conditioning, smoke, dust, cold air or excessive ventilation, very hot air, driving or commuting by train, bus with excessive air blasting on the face (like standing in the door on a train or sitting next to a window on a bus) you might find that you need to remove your prosthesis more often to clean it.

Attention

If you have had your prosthesis polished annually by your Occularist and suspect the presence of an infection, it is advisable to consult your Ophthalmologist.

During medication, if eye drops or an ointment has been prescribed, apply with the prosthesis in the cavity, it is not recommended to let the cavity heal or recover from an infection, without the presence of a well cleaned prosthesis. If you are wearing an old prosthesis, which can damage the tissues, your Ophthalmologist or Occularist should place a temporary prosthesis called a “conformer”. This will facilitate the healing process or recovery from an infection with less risk of the socket contraction. Afterwards the Ocularist will proceed with the fabrication of a new custom-made ocular prosthesis. For hygienic reasons many people admit to having boiled their prosthesis or having disinfected it in or with alcohol, both practices should be absolutely abolished as they can cause irreversible damage to the prosthesis.

Visit your Ophthalmologist and your Ocularist annually for an examination, verification and, if required, polishing. If you have problems or questions, during the year do not hesitate to contact your Ocularist or Ophthalmologist.

For further details you can write to:

Chandrashekhar Chawan

Director - Shekhar Eye Research Pvt Ltd

108 Falcon Court, Hari Om Nagar, Mulund (E), Mumbai 400081 IndiaT +91 22 25327459 / 56 Fax: +91 22 25327410 Cell +919892416978  

Email: shekhar@shekhareye.com

Website: www.shekhareye.com 

11 NATURAL EYE MOVEMENTS (figs. 11.1 & 11.2)

Even with custom made artificial eye patients cannot get totally natural movements of prosthesis as it is not attached or sutured to the tissue behind, in the socket. It is just sitting right in the socket, so that there is less friction while moving the eye. But when looking at the extreme right, left and upwards the prosthesis do not move to such extent, due to tissue restriction and weight. Due to this restricted movement, patient has to move his/her head in the direction of gaze rather than moving his/her eyes.

Other people can make out the artificialness in the prosthetic eye, as artificial eye does not move in conjunction with the natural eye.

In order to overcome this shortfall “Intra Orbital Implants” made of Hydroxyapatite is used.

Dr. Arthur Perry of USA had first implanted the intra orbital implant of Hydroxyapatite in May 1985. Now it is famous in the world under the name “Bio Eye hydroxyapatite Implant”, which is supplied by “Intra Orbital Implants, Inc. USA.

In India Dr. Quresh Maskati first implanted this, hydroxyapatite intra orbital implant, in 1992.

The hydroxyapatite implant is surgically placed within the orbit and the tissue is closed over the implant. A temporary conformer is placed over the implant and under the eyelids to maintain the space for the artificial eye.

After 6 to 8 weeks an Ocularist can make a custom made artificial eye to match the patient’s good eye. This eye is fitted over the implant and will move in conjunction with the natural eye.

If extreme movement is desired, the Ophthalmologist will drill a hole in the implant after 4 to 6 month as this much time is required for the blood vessels to grow in the implant, thus it becomes a part of your body. A peg is inserted into the hole and a month later, an Ocularist can modify the back of the artificial eye to accept the head of the peg. This forms a ball and socket attachment. If there is no room for the ball and socket, an attachment peg can be directly glued to the back of the artificial eye. After this attachment the artificial eye will move to the extreme ends with the good eye and the patient gets full benefit of the implanting procedure.

The final result in each case is different depending upon the condition of the orbit, muscles and surrounding tissues.

Even with a pegged artificial eye one cannot get 100% eye movement. It is advisable to put some kind of intra orbital implant after an eye removal in order to fill up the lost volume of the socket and for better fitting of an artificial eye.

12 READY MADE Vs CUSTOM MADE EYE

“Custom Made Artificial Eye” is made by using “impression technique” by, taking an impression of the patient’s eye socket i.e. tailor made specifically for a given patient to his/her measurements , it is not simply just a question of matching the iris and scleral shades and a fixed back curvature as a stock eye.

Many ready-made eye manufacturers give iris and scleral shade matching prosthesis and call it custom-made; it is not a custom-made artificial eye in any sense.

The only advantage offered by a ready-made artificial eye is that it is cheap and readily available.

In the long run the disadvantages become obvious:

Poor matching with the good eye as it is not painted to match the good eye.

Little or no movement as the back surface of a ready-made artificial eye is hollow and not made to match the tissue behind

the eye. Hence the artificial eye only looks straight ahead and cannot follow the other eye movements.

Whole weight of the ready-made artificial eye is on the lower lid therefore in a few years the lower lid starts sagging down requiring further reconstructive surgery of the lower lid.

Tissue in the lower fornix grows in an upward direction due to loss of facial attachment of lower fornix to periosteum, trying to fill up the hollow back of the ready-made artificial eye over a period of time, leading to falling off of the prosthesis, on looking up, requiring the patient to undergo reconstruction of the fornix surgically to correct the position.

Discharge and watering becomes a problem with ready-made artificial eye. Due to constant rubbing of the tissue behind patient starts to get heavy discharge frequently that tends to accumulate in the hollow back of the prosthesis. Due to accumulation of the discharge tissue secrets more discharge, requiring frequent cleaning which restricts wearing period, this creates awareness of the deformity creating an inferiority complex for the patient.

Often ready-made artificial eye can give proptosis effect i.e. one eye looking bigger than the other.

If the ready-made artificial eye is used during sleeping hours, both the eyelids stick together due to heavy discharge in the morning.

To overcome all these problems and complications a custom made artificial eye is the solution.

The advantages of a custom-made artificial eye:

Close matching with the natural eye, as it is hand painted to match the other eye.

Greater movement due to exact matching of the back of the prosthesis with the tissue structure in the socket.

Virtually no discharge or watering as there is no or very little friction with the socket tissue and custom-made artificial eye; tears also get properly drained in to the punctum in most of the cases.

Patient can wear the custom-made artificial eye days custom-made artificial eye together continuously including sleeping hours, as there is very little discharge in the morning similar to the normal eye.

Most of the weight of the custom-made artificial eye is distributed over the tissue inside and not on the lower lid. Peg

attachment to the artificial eye can take all the weight of the prosthesis on it placing no pressure on the delicate lower lid.

There are no complications like lower lid sagging or inverted lower fornix or contracted socket with the custom-made artificial eye made by using impression technique.

Modifications are possible with the custom-made artificial eye to solve many problems like mild to severe ptosis, proptosis or need for socket expansion with surgery etc.

Custom-made ocular prosthesis play a very important role in the development of orbits of anophthalmic / microophthalmic children i.e. children born without an eye or if an eye has had to be removed surgically at an early age.

If the advantages of newer developments in the field of ocular prosthesis and cosmetic surgery (Oculoplastic surgery) are used totally, patients with disfigured eye can be rehabilitated socially and psychologically.

13 ANOPHTHALMIA AND MICROPHTHALMIA (fig.13.1)This chapter is contributed by researcher at Albert Einstein Medical Centre (AEMC) in Philadelphia

Anomalies of the eye and central nervous system are among the most common encountered in paediatrics. In the case of Anophthalmia and Microphthalmia, it is thought it is thought to be on a continuuam ranging from mild coloboma (a keyhole or a notch like defect in the retina, iris or optic nerve) to severe anophthalmia. Anophthalmia is a medical term used to describe the complete absence of the globe and eye tissue from the orbit. Microphthalmia is defined as small eyes and can range from mild to severe. The terms Anophthalmia and Microphthalmia are often used interchangeably, since CT scan and MRI may show some remnants of either the globe or surrounding tissue. Anophthalmia / Microphthalmia (A/M) may affect only one eye with the other being normal or both eyes, resulting in blindness.

After congenital cataract, Anophthalmia and Microphthalmia are among the most frequent eye malformations in humans.

(1) The exact incidence of A/M is unknown. In a recent study in England, the overall prevalence of A/M was 1.0 per 10,000 births.

(2)Anophthalmia can be congenital (at birth) or acquired later in life (after an injury). Congenital anophthalmia and microphthalmia can occur alone or along with other eye problems (e.g. cataract or

coloboma) or birth defects (e.g. heart or brain defects). Anophthalmia and Microphthalmia may result from inherited genetic mutations, sporadic (by chance) genetic mutations, chromosome abnormalities, parental environmental insult (maternal diabetes, infection or alcohol) or other, as yet unknown, factors.

Comprehensive Health Care Team

When a child is born with Anophthalmia/Microphthalmia, a comprehensive health care approach is essential to help the baby and the family to meet the challenges related to A/M and to live as healthy a life as possible. The health care team should include evaluations by the following professionals, either immediately or shortly after birth.

1. Paediatrician – A physician specialising in caring for children.2. An Ophthalmologist – A physician specialising physician

specialising in problems related to the eye. An Ophthalmologist often will make the diagnosis of A/M.

3. Ocularist – A health care professional specialising in prosthetic (artificial) devices for the eye.

4. Oculoplastic surgeon – A physician who specialises in surgery of the eye. Not all people with A/M will require surgery.

5. Geneticist – A physician who is an expert in genetic conditions.6. Genetic counsellor – A medical professional specialising in support

and information.

The genetic team can help the family to co-ordinate special care and early intervention for the child. If a specific diagnosis is made to explain the etiology of A/M, the genetics team can educate the family and health care team and provide anticipatory guidance and prognosis based on the information available from all sources. In addition, the genetics team can discuss the possibility of having another child with A/M.

7. An early intervention specialist/teacher – A professional who works with children who are visually impaired in one or both eyes to learn and develop in a sighted world. An example of an early intervention service is Orientation and Mobility training. Early intervention specialists will determine what services your child may need. Early intervention helps the child to maximise their development and reach their full potential.

Genetics of A/M

In each cell of our body, are the chromosomes which are tiny structures that carry our genetic information, which tells our bodies how to develop and to function throughout our life. Our chromosomes arranged in 23 pairs (total of 46) with one chromosome of each pair, coming from the mother (X chromosome) and the other from the father (Y chromosome). Our chromosomes contain thousands of genes, which are made up of DNA. Sometimes a change occurs in a gene which is called a mutation. If a mutation develops in the gene concerned with eye development, it could potentially affect how the eye develops during pregnancy. An eye is affected in about one-quarter of all inherited diseases, thus possible genetic defect causes eye malformation, must be considered as a possibility. A/M has many different potential causes including genetic conditions such as chromosomal disorders, single gene disorders and multifactoral disorders.

A chromosomal disorder means there is an extra piece or missing or rearranged piece of all or part of any chromosome. An example of a chromosome disorder is Down syndrome. These individuals have three copies of the chromosome number 21 instead of the usual 2. A chromosome disorder can be determined when you child has their chromosomes analysed with a simple blood test. However, if your child has a normal chromosome analysis, it does not rule out a genetic cause of A/M. A normal chromosome test only means that the cause is unknown at that time.

A single disorder occurs as a result of a mutation in one gene or both genes of a pair of chromosomes. Examples of a single gene disorders are cystic fibrosis, sickle cell disease and Tay-Sachs disease. Researchers are currently working on locating and analysing the gene(s) involved in a normal eye development which may lead to answers about A/M and enable geneticists to provide more accurate counselling and recurrence risks.

Multifactoral disorders are the result of a genetic predisposition plus environmental influence that leads to a disease. The exact genes and environmental influences are usually not known. Examples of conditions that are thought to be multifactoral are heart diseases and diabetes.

A comprehensive genetics evaluation may yield a diagnosis of a syndrome or disorder with A/M as one of its findings. If a diagnosis is made, the recurrence risk of that disorder can be explained.

Unfortunately, many times it is difficult to make a diagnosis. Without a specific diagnosis, genetic counselling and determination of recurrence risks are difficult. At this time, parental testing to look for normal eye and lens development is available only in the form of high level ultrasound. Genetic counselling is recommended prior to a future pregnancy.

Treatment of A/M

Facial development occurs very rapidly in an infant and young child. It is believed that 90% of orbital growth is completed by the age of 5 years. Growth and development of the face depends on the presence of an average size eye in the orbital cavity. If an eye is very small or if it is totally absent, the face cannot grow properly. Therefore, treatment for A/M should begin as early as possible.

Treatment begins with an Ocularist. They may decide to use two basic approaches. The first, most common approach to treatment is the insertion of a conformer. A conformer is a tiny plastic device that looks like a ball with a stem. The conformer helps to support the growth of the eye socket and facial bones and to expand the eyelid opening.

The second approach is to make a custom-made conformer using the impression technique. This approach allows the conformer to be shaped exactly as per the child’s orbit cavity. One can also make an artificial eye with the impression technique instead of a conformer, which will help give an improved cosmetic appearance along with help expansion of the socket and orbit. In some cases, the Ocularist will need to examine the child under general anaesthesia in an operating room. At the same time he will make an impression of the eye socket in order to make a custom made prosthetic device.

The Ocularist will decide which treatment approach is best for the child, depending on the individual needs of the child. In both approaches the prosthetic device will need to be changed frequently as the child grows.

During the examination, the Ocularist will need to hold the baby still in order to fit the conformer. The examination is not usually painful but may be disturbing for the child who does not understand what is happening to it. The Ocularist will separate the baby’s eyelids in order to examine the socket. The baby may cry and resist examination (by a stranger), even with the most gentle handling.

The prosthetic eye/conformer does not make a person with A/M see. With our current knowledge and science, there is no device that will allow a child with A/M to see. Anophthalmia is a condition that requires

visiting the Ocularist throughout life. During the child’s first year, many ocular devices will be needed as the child grows and as the socket size changes. The child may need weekly, bi-weekly or monthly visits to the Ocularist. As the child grows older the frequency of visits will decrease.

The actual number of visits required differs from individual to individual. It may take some time for the child to get used to wearing prosthesis. It should not cause pain but if the child’s eye looks red or the child indicates pain by frequent rubbing or pulling at the eye you should contact your Ocularist immediately. Never remove the prosthesis without the knowledge of your Doctor or Ocularist. Children may remove and play with the prosthesis. You should replace it (in the socket) following the procedure taught by your Ocularist. If you are not able to replace it, contact your Ocularist without delay, as the socket may begin to shrink if the prosthesis is not in place.

Over time and through necessity, everyone can learn to care for the baby’s eye prosthesis and needs. Any concerns and feelings should be discussed with your Ocularist, who is used to dealing with concerns about these very important topics.

Recommendations for Individuals with A/M

Children may be born with A/M only, while others, may have additional associated findings. It is suggested that any child born with A/M have the following evaluations and studies carried out. These evaluations and studies will monitor for potential problems associated with A/M and help to ensure that children with A/M live as healthy a life as possible. This may be a helpful list to give to the Paediatrician. 1. Ophthalmologist / Oculoplastic surgeon. 2. Ocularist. 3. Clinical Geneticist. 4. Early intervention specialist and vision therapist (even for children with only one eye affected). 5. Cardiology evaluation if a murmur is heard. 6. MRI or CT of brain and orbits. 7. Chromosome study. 8. Hearing evaluation. 9. Renal ultrasound. 10.TORCH titers (infection studies). 11. Dental examination when teeth erupt (especially for males). 12. Ophthalmology examination of BOTH parents (in order to rule

out eye problems that may not be affecting vision, such as coloboma which can result in a more severe condition in a child).

Support Group information for A/M

The international children’s anophthalmia network (ican) is a support group of healthcare professionals and family members of persons with anophthalmia and microphthalmia. Ican offers support to parents and family members, educational materials, quarterly newsletters and bi-yearly family conferences. Ican can be contacted through their hotline +1-800-580-ican (4226) or their internet web page at www.ioi.com/ican

Research and A/M

Albert Einstein Medical Centre (AEMC) in Philadelphia works with ican and has a Clinical Registry of individuals with anophthalmia and microphthalmia from all over the world. The Clinical Registry is compiling information on pregnancy histories, maternal medical histories, family histories as well as environmental exposures. The goal is to determine a more accurate incidence of anophthalmia and to better identify all the syndromes that include anophthalmia and to better identify all the syndromes that include anophthalmia. The registry is a wealth of information for individuals with anophthalmia, their families and healthcare providers.

Currently at AEMC, gene screening for eye development genes is being undertaken in co-operation with several different laboratories worldwide. All the laboratories are looking for changes in eye development genes as a possible cause of A/M. Eye development genes have the special function of being the blueprint for eye development during pregnancy. Several genes are known to be responsible for eye development in laboratory animals. Similarly genes exist in humans. The DNA samples are analysed to determine if a change exists, which alters the blueprint during development and leads to A/M. To participate in gene screening research, contact ican at 1-800-580-ican (4226) or AEMC at 215-456-8722.

References

1. Gotz W. Transgenic models for eye malformations. Ophthalmic Genetics 1996; 16:85-104.

2. Dolk H., Busby A., Armstrong B., Walls PH. Geographical variation in anophthalmia and microphthalmia in England,

1988-94. British Medical Journal, 1998; 317:905-909.

14 AMERICAN SOCIETY OF OCULARISTS

The American Society of Ocularists is an International, non-profit, professional and educational organisation founded in 1957 by technicians specialising in the fabrication and fitting of custom artificial eyes.

The organisation’s purpose is to improve and promote research in development of ophthalmic prosthetics, to advance the methods, techniques and skills of the Ocularist membership, and to provide the public with continual improvement in all fields and activities in which Ocularists engage. Our members adhere to the Society’s Standard Operating Procedures for fitting and fabrication of custom made ophthalmic prosthesis.

Research, education and standards form the benefits to our members. Persons presently working in Ocularistry, or engaged in an ancillary business or profession, may apply for membership.

A training curriculum, developed and administrated by the Education Committee of the ASO, provides courses at semi-annual conferences to prepare Ocularists certification and re-certification examinations of National Examining Board of Ocularists. http://www.generation.net/~oculoplast/nebo.htm

Research of new techniques stressing the benefits of custom-made ocular prosthetics and product development, is published in the Society’s Annual Journal of Ophthalmic Prosthetics.

15 FREQUENTLY ASKED QUESTIONS

What is an Ocularist?

An Ocularist is a carefully trained technician skilled in the arts of fitting, shaping and painting ocular prosthesis. In addition to creating it, the Ocularist trains the patients (or parents in case of a baby patient) how to handle and care for the prosthesis and provides long term care through periodic examinations.

How long have artificial eyes been around?

Artificial eye making has been practiced since ancient times. The first ocular prosthesis, were made by Roman and Egyptian priests, as early as the fifth century BC. In those days, artificial eyes were made of painted clay, attached to cloth and worn outside the socket. It took many centuries for the first in-socket artificial eye to be developed. At first, these were made of gold with coloured enamel.

In the later part of the sixteenth century, the Venetians started making artificial eyes of glass. These early glass eyes were crude, uncomfortable to wear and fragile. Even so the Venetians continued making them and kept their method secret until the end of eighteenth century. After that, the centre for artificial eye-making shifted to Paris for a time; but by mid-nineteenth century, German glass blowers had developed superior techniques and the centre for glass eye making moved to Germany. Shortly thereafter, glass eye making was introduced in the United States. During World War II, the imported German glass used for glass prosthesis became unavailable in the United States. As a result of this shortage, the U.S. Government, in conjunction with a number of American firms, popularised the techniques of making artificial eyes out of acrylic plastic.

The popularity of this method has continued to increase over the years, and today vast majority of patients wear ocular prosthesis made of acrylic.

What is the difference between “Stock” and “custom” eyes?

“Stock” or “Ready-made” ocular prosthesis are mass-produced. Since a “stock eye” is not made with any particular person in mind, it does not fit any particular patient. A “custom” ocular prosthesis, on the other hand, is made by your Ocularist to fit you and you alone.

How often do you have to see an Ocularist?

The ocular prosthesis, like hard contact lenses, needs to be polished regularly in order to maintain the acrylic finish and ensure the health of the surrounding tissues. It is generally recommended those infants under 3 years of age, to be seen every 3 months; patients under 9 years of age, twice yearly and all other patients, at least once a year.

How much does an artificial eye cost?

In the United States, the current cost for an artificial eye ranges from US$ 3000 to US$ 4000. The cost of sclera shell prosthesis ranges from Us$3500 to US$ 4500. The fee will largely depend on the amount of work involved in order to achieve a satisfactory result. It should be

understood that it is very difficult for any Ocularist to quote a fee without first examining the patient. The majority of Ocularists offer the initial consultation visit without obligation and the charges are explained at the time of the initial consultation visit.

Does Medical Insurance pay for an Artificial Eye?

If insurance coverage is available, most Ocularist practices will assist you in every possible way to obtain full benefits of your policy in the USA. However, it should be noted that the patient, (or in case of children a parent or guardian) is always responsible for the payment, in case of HMO’s it is always necessary to obtain a referral before work can begin.

What is the American Society of Ocularists?

The American Society of Ocularists (ASO) is a professional organisation, which was established by a group of skilled American Ocularists in1957. Their purpose was to promote high standards through research and education in the field of Ophthalmic Prosthesis. Today the ASO maintains quality Ocularistry through its formal education, training and continuing education programmes.

How do I find a good Ocularist?

In most states, there are no laws governing Ocularists. When choosing an artificial eye-maker, you should consult your state regulations and look for the following credentials:

Membership of the American Society of Ocularists. Certification by National Examining Board of Ocularists.

How does a person become an Ocularist?

There are no schools that teach Ocularisty. A person must learn how to make artificial eyes through an apprenticeship with an approved Ocularist (a Board Approved Diplomate Ocularist). The ASO apprentice Program requires that the apprentice must study all aspects of ocular prosthetics and spend five years (10,000 hours) in practical training. The apprentice must also successfully complete 750 credits of related study courses offered by the Education Program of the ASO. Upon successful completion of all requirements, the title, Diplomate of American Society of Ocularists, is awarded.

Does the Society arrange apprenticeships?

Apprenticeships are not arranged by the American Society of Ocularists. A person seeking training must contact Ocularist in their area and locate

someone who is able to hire and train an apprentice. For people willing and able to relocate, we suggest attending one of the biannual conferences to meet Ocularists from different parts of the country.

Can I apprentice with any Ocularist?

To qualify for the Society’s apprenticeship program, you must train with a Board Approved Diplomate Ocularist (BADO).

I already make artificial eyes. Do I have to become an apprentice?

Persons who are already working as Ocularists may apply to the Society’s Associate program.

Aren’t there classes I can attend somewhere to learn to become an Ocularist?

The American Society of Ocularists is the only organisation that offers educational training in Ocularistry. Classes are offered at the Society’s bi-annual meetings, and are designed to prepare Ocularists to take their certification exams.

What courses should I take to increase my chances of becoming an apprentice?

Although the science provides a good base, no special background is required to enter an apprentice program.

Who certifies Ocularists?

The National Examining Board of Ocularists (NEBO) is an independent entity whose directors come from the following participating organisations:

American Academy of Ophthalmology. American Board for Certification of Orthoptics and Prosthetics. American Society of Ocularists. Public Member

NEBO awards the title, Board Certified Ocularist (BCO), to those Ocularists who successfully complete a comprehensive four-part written and practical examination. All BCOs must complete continuing education requirements and be rectified by NEBO every six years.

For further details write to:

Cathi GuerreroExecutive Director

American Society of Ocularists,

1001 Mohawk Street, #16,

Bakersfield, CA 92209, USA

Phone: +1 661 633 1746

e-mail: cathi@ocularist.org Web site: http://www.ccularist.org