DRY EYEDR K HARIPRIYA

DefinitionDry eye is a multifactorial disease

of the tears and ocular surface that results in symptoms of discomfort, visual disturbance and tear film instability with potential damage to the ocular surface.

It is accompanied by increased osmolarity of the tear film and inflammation of the ocular surface.

Tear film

Introduction Dry eye is recognized as a

disturbance of the Lacrimal Functional Unit (LFU), an integrated system comprising the lacrimal glands, ocular surface (cornea, conjunctiva and meibomian glands) and lids, and the sensory and motor nerves that connect them

This functional unit controls the major components of the tear film and responds to environmental,

endocrinological and cortical influences.Its overall function is to -preserve the integrity of the tear film, -transparency of the cornea, -quality of the image projected onto the retina

Trigeminal sensory fibers arising from the ocular surface run to the

superior salivary nucleus in the pons, efferent fibers pass nervus intermedius

pterygopalatine ganglion.

Here, postganglionic fibers arise, which terminate in the lacrimal gland, nasopharynx, and vessels of the orbit.

Another neural pathway controls the blink reflex, via trigeminal afferents and the somatic efferent fibers of the seventh cranial nerve.

SSWS

Effect of environmentMilleu interiorLow blink rate ,agingWide lid aperture Low androgen poolSystemic drugsMilleu exteror Low relative humidityHigh wind velocityOccupational environment

Aqueous Tear-Deficient Dry Eye (Tear Deficient Dry Eye; Lacrimal Tear Deficiency)

Sjogren syndrome: It is an exocrinopathy in which the lacrimal

and salivary glands are targeted by an autoimmune process.

The lacrimal and salivary glands are infiltrated by activated T-cells, which cause acinar and ductular cell death and hyposecretion of the tears or saliva.

Inflammatory activation within the glands leads to the expression of autoantigens at the surface of epithelial cells

Sjogrens syndrome The precise triggers leading to

autoimmune acinar damage are not known in full, but risk factors include genetic profile, androgen status, and exposure to environmental agents, ranging from viral infections affecting the lacrimal gland to polluted environments.

A nutritional deficiency in omega-3- and other unsaturated fatty acids has been

reported in patients with SS

Sjogrens syndrome Two typesPrimary SS consists of the occurrence

of ADDE in combination with symptoms of dry mouthSecondary SS consists of the features

of primary SS together with the features

of an overt autoimmune connective disease, such as rheumatoid arthritis, SLE, etc..

Non-Sjogren Syndrome Dry EyePrimary lacrimal gland

deficiencies:Age-related dry eyeCongenital alacrimaFamilial dysautonomia

Age-related dry eye

Ductal pathology Peri ductal, inter acinar fibrosis Paraductal blood vessel loss Acinar atrophy Low grade dacryoadenitis

Congenital Alacrimarare cause of dry eye in youth. It is also part of certain

syndromes, triple A syndromeProtien ALLADIN

Familial dysautonomiaDevelopmental , progressive

neuronal abnormality of the cervical sympathetic and parasympathetic innervations of the lacrimal gland and a defective sensory innervation of the ocular surface

Generalized insensitivity to pain is accompanied by a marked lack of both emotional and reflex tearing,

NSDESecondary lacrimal gland

deficienciesLacrimal gland infiltrationSarcoidosisLymphomaAIDSLacrimal gland ablationLacrimal gland denervation

NSDEObstruction of the lacrimal gland

ducts:TrachomaCicatricial pemphigoid and

mucous membrane pemphigoidErythema multiformeChemical and thermal burns

NSDEReflex hyposecretionReflex sensory block Contact lens wear Diabetes Neurotrophic keratitisReflex motor block Cranial nerve damage Multiple neuromatosis Exposure to systemic drugs

Evoperative dry eyeIntrinsic causesMGDDisorders of lid apertureLow blink rate

Extrinsic causes:Occular surface disorders Vitamin A Deficiency Topical Drugs and

Preservatives Allergic conjunctivitis

Inspection Signs of associaed systemic

diseasesIndications of personnel habitsOcular disease(lid malposition)

Evaluation of tear filmTear meniscus heightTBUT Meniscometry : Tear meniscus

radius, height and cross sectional area

1MM, CONVEX-NORMAL<0.3 MM IS abnormalTear film lipid layer interferometry color comparison table kinetic analysis

TESTS OF TEAR PRODUCTIONSCHIRMER TESTBASICSCHIRMER 1SCHIRMER 11

Inference - > 15 mm - normal, 6 to 10 mm - borderline dry, < 6 mm - impaired secretion.

Tear composition assaysTear Osmolarity

Rose Bengal staining – The dye has an affinity for dead or devitalized epithelial cells and for areas devoid of mucus.

Van Bijsterveld scoring system – divide the ocular surface into three zones:

• Nasal bulbar conjunctiva, Cornea Temporal bulbar conjunctiva. Each zone is then given a score of ‘0’

(no stain) to ‘3’ (confluent stain). Scores in each eye is totaled. A score of 3.5 or greater indicates positive for keratoconjunctivitis

Newer technologies MEIBO METRY Casual Lipid level (expressed as

arbitrary optical density units) is calculated as (C-B), where C is the casual reading, B is the reading from the untouched tape

MEIBO GRAPHY /MEIBO SCOPY Finoff transilluminator Most reliable test in patients with

ectodermal dysplasia syndrome

Brush Cytology Technique1) squamous metaplasia, 2) detecting inflammatory cells 3) expression of several surface

markers on the ocular surface epithelium

Flow cytometry in impression cytology

HLA DR expression by epithelial cells, gold standard for inflammatory assesment

Ferning Test (TFT ) TO DIAGNOSE Quality of tears (electrolyte

concentration), KCS, HyperosmolarityThe patterns of crystallization (ferning) are

classified in 4 classes: Type 1: uniform large arborization, Type 2: ferning abundant but of smaller size; Type 3: partially present incomplete ferning; Type 4: no ferning.Types 1 & 2 are reported to be normal and

Types 3 & 4 reported to be abnormal

Fluorophotometry (Fluorimetry) Tear Function IndexTFI is the quotient of the Schirmer

test value and the Tear clearance rate (TCR).

A TFI of less than 40 is 100% sensitive for patients with SS dry eye

MANAGEMENTA. Tear supplementation:

lubricants B. Tear RetentionC. Tear stimulation: secretagoguesD. Biological tear substitutesE. Anti-inflammatory therapyF. Essential fatty acidsG. Environmental strategies

A. Tear supplementation: lubricants

Hypotonic or isotonic buffered solutions containing electrolytes, surfactants, and various types of viscosity agents.

Ideal artificial lubricant should be preservative-free, contain potassium, bicarbonate, and other electrolytes and have a polymeric system to increase its retention time.

Physical properties Neutral to slightly alkaline pH. Osmolarities 181 to 354 mOsm/L.

Tear supplementation: lubricantsElectrolytes potassium, bicarbonateOsmolarityViscosity agents: prolong ocular

surface contact, increasing the duration of action and penetration of the drug

Eye ointments and gels

B. Tear Retention 1. Punctal Occlusion Types absorbable and nonabsorbable. The former are

made of collagen or polymers and last for variable periods of time (3 days-6 mnths).

The nonabsorbable “permanent” plugs include silicon plugs, consists of a surface collar resting on the punctal opening, a neck, and a wider base

Herrick plug is shaped like a golf tee and is designed to reside within the canaliculus.

cylindrical Smart plug: expands and increases in diameter in situ, due to thermodynamic properties of its hydrophilic acrylic composition.

Punctal Occlusion Indications patients who are symptomatic of

dry eyes have a Schirmer test (with anesthesia) result less than 5 mm at 5 minutes, and show evidence of ocular surface dye staining

Contra indicationsAllergy to the materials used in

the plugs to be implanted,punctal ectropion, pre-existing nasolacrimal duct

obstruction,clinical ocular surface

inflammation,

ComplicationsExtrusionInternal migration of a plug, Biofilm formation Infectionpyogenic granuloma formation

Tear RetentionMoiature chamber spectaclesContact lenses

Tear Stimulation: SecretogoguesDiquafosol RebamipideGefarnateEcabet sodium

D. Biological Tear SubstitutesSerumSalivary Gland Autotransplantation:Indicated only in end-stage dry eye

disease with an absolute aqueous tear deficiency (Schirmer-test wetting of 1 mm or less), a conjunctivalized surface epithelium

persistent severe pain despite punctal occlusion and at least hourly application of unpreserved tear substitutes.

Due to the hypoosmolarity of saliva, compared to tears, excessive salivary

tearing can induce a microcystic corneal edema, which is temporary, but can lead to epithelial defects.

E. Anti-Inflammatory Therapy1. Cyclosporine2. Corticosteroids3. Tetracyclinesa. Properties of tetracyclines and

their derivatives1) Antibacterial properties2) Anti-inflammatory3) Anti-angiogenic properties

Essential fatty acids Environmental strategies: Use of room humidifiers Avoid extreme/harsh environmental conditions.

Treatment recommendations by severity level

Level 1:Education and environmental/dietary

modificationsElimination of offending systemic medicationsArtificial tear substitutes, gels/ointmentsEye lid therapyLevel 2:Anti-inflammatoriesTetracyclines (for meibomianitis, rosacea)Punctal plugs ,SecretogoguesMoisture chamber spectacles

Treatment recommendations by severity level

Level 3:SerumContact lensesPermanent punctal occlusionLevel 4:Systemic anti-inflammatory agentsSurgery (lid surgery, tarsorrhaphy;

mucusmembrane, salivary gland, amnioticmembrane transplantation)

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