Conjunctiva - Thieme Medical .Conjunctiva AnatomyandPhysiology Theconjunctivareactspromptlytoendogenousandexo-genousirritantsandisthusasensitiveindicatorofcon-

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Conjunctiva

Anatomy and PhysiologyThe conjunctiva reacts promptly to endogenous and exo-genous irritants and is thus a sensitive indicator of con-tact lens complications. Practically any problem causeddirectly or indirectly by contact lenses is associatedwithconjunctival changes (though not all conjunctivalchanges are due to contact lenses). Lid disease caused bycontact lenses is associated with changes of the tarsalconjunctiva, and corneal disease caused by contactlenses is associated with changes of the bulbar conjunc-tiva.

Changes of the lids and cornea should be soughtwhenever a contact lens wearer presents with con-junctivitis, because, in contact lenswearers, the lids, cor-nea, and conjunctiva constitute a functional unit. Thecomplications that arise are generally due to a distur-bance of the physiological, metabolic, and toxicologicalinterrelationship of these three structures. This inter-relationship is the central theme of contactologicalresearch and accounts for a major part of the ophthal-mologists work in caring for the contact lens-wearingpatient.

The conjunctiva is a mucousmembrane that extendsfrom the lid margins to the limbal region of the globe. Itis a well vascularized, translucent membrane with twoportions, tarsal (palpebral) and bulbar. The tarsal con-junctiva is tightly bound to the underlying tissue on theinner surface of the lid, while the bulbar conjunctiva ismore loosely applied to the sclera, except in the limbalarea. The fornix (zone of transition between the tarsaland bulbar conjunctiva) lies at the most remote area ofthe surface of the eyeball and forms the base of the con-junctival sac (cul-de-sac).

The conjunctiva is a mucous membrane containingmany secretory cells; the most important of these forcontact lens wearers are the goblet cells. When theirfunction is impaired, lacrimation becomes deficient, theeye dries out, and a foreign body sensation ensues thatmakes lens-wearing intolerable.

Tarsal Conjunctiva

Follicular Swelling, Papillary Hypertrophy,Giant Papillary Conjunctivitis

Symptoms: Severe itching while wearing lenses; burn-ing; increased secretions; impaired visual acuity (VA).

Clinical findings: Hyperemia, follicular swelling; papil-lary hypertrophy of the tarsal conjunctiva; recurrentdeposition of hydrophobic material on lens surfaces.

Hyperemia, follicular swelling, and papillary hyper-trophy of the tarsal conjunctiva are the classic signs ofGPC in contact lens wearers, a complication that is not atall rare inwearers of hard or soft lenses. This condition isbecoming significantly more common, not least becauseof air pollution.

Both in etiology and in phenotype, GPC resemblesvernal conjunctivitis (vernal catarrh), a condition seen inthe springtime in patients with an allergic predisposi-tion. GPC is caused by proteins from the lacrimal fluidthat are presumably denatured by lens-hygiene solu-tions and thereby become immunologically active.Deposited on the surface of the lens, these proteins act asantigens, towhich antibodies thenbind. The sandwichoflens, antigen, and antibody rubs on the tarsal conjunc-tiva, causing increased conjunctival swelling and secre-tionsthe vicious cycle of GPC.

The hallmark of GPC is the coating of the contact lenssurface with a strongly adherent protein layer, whichpierces the film of tear fluid over the lenswithin secondsof insertion, leading to diminished visual acuity and in-creased glare. The case history generally points to thediagnosis: The patient wears lenses without complica-tions forweeks ormonths and then, suddenly, a problemdevelops. A few minutes after lens insertion the patientexperiences burning, chafing, and itching in the eyes.Tears and a film deposited on the surface of the lens im-pair visual acuity within a few seconds after the eyes areopened, and until the next blink. Conjunctival secretionscause the eyelids to stick together and limit the mobilityof the contact lens during blinking and eye movements.

Examination reveals the following: the contact lensis barely mobile or immobile on the surface of the eyeand is coated with a grayish-white film that makes itlook dry and dull. The lids are mildly swollen, and theirmargins are coated with dried yellowish-white secre-tion. The bulbar conjunctiva is mildly injected; evertingthe lids reveals a massive papillary swelling of the tarsalconjunctiva, which is made even more evident withfluorescein staining. GPC can be classified into fourstages (Table 9).

Conjunctiva

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57

59

58

60

Fig. 55 Scarring of the tarsal conjunctiva of the lower lid afterdecades of wearing hard PMMA lenses.

Fig. 56 Tarsal conjunctiva 1 hour after test wear of a rigid con-tact lens for myopia; injection of conjunctival vessels.

Fig. 57 Isolated hyperemia of the upper lid conjunctiva causedby protein deposits on the anterior surface of a soft contactlens.

Fig. 59 Injection of the upper lid conjunctiva; focal conjuncti-val atrophy after 18 years of wearing hard lenses for kerato-conus; tear deficiency.

Fig. 58 Mild hyperemia of the tarsal conjunctiva; mechanicalirritation of the conjunctiva on the initial fitting of a hard lens.

Fig. 60 Upper-lid hyperemia and edema; allergic reaction tochlorhexidine.

3 Pathologic Findings

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61

63

62

64

Fig. 61 Upper-lid hyperemia; mild cockscomb swelling of theconjunctiva indicating chronic irritation; hard contact lens wornfor 6 years.

Fig. 63 GPC reaction on upper lid; marked hypertrophy of thepapillae; hyperemia.

Fig. 62 Early GPC, characterized by hyperemia and moderatepapillary hypertrophy; soft hydrophilic lens.

Fig. 64 GPC stage 12; isolated tarsal conjunctival hyperemia;papillary hypertrophy in the region of the fold.

Conjunctiva

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Fig. 65 GPC stage 23; papillary hypertrophy; identical pic-ture to vernal conjunctivitis.

Fig. 66 GPC in a CAB lens wearer; stage 2; fluorescein staining.

Fig. 67 GPC follicular swelling in the region of the lower con-junctival fold; soft contact lens worn for 3 months.

3 Pathologic Findings

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Fig. 68 GPC stage 3; fluorescein staining; PMMA lens worn for11 years.

Fig. 69 Marked GPC, stage 3; fluorescein staining; gel contactlens worn for 4 months.

Fig. 70 GPC; scarring; 9 months of wearing a fluorosiliconecarbonate lens.

Conjunctiva

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Table 9 Stages of giant papillary conjunctivitis

Stage Papillaryappear-ance

Mucus Lenswearingcomfort

Visualacuitywith lens

1 Littlechange

Minimal Good Very good

2 Diameterup to0.5 mm

Moderate Slightlydecreased

Still good

3 Diameterup to0.7 mm

Moderate Markedlydecreased

Variable

4 Diametergreaterthan0.7 mm

Copious Lenses un-wearable

Markedlydiminished

Differential diagnosis: Other conditions resembling GPCinclude other allergic reactions of the conjunctiva, auto-immune conditions, and (typically in the springtime)primary vernal conjunctivitis independent of the wear-ing of contact lenses.

Prevention: Meticulous daily lens hygiene, frequent useof protein removers, and a temporary cessation of lenswearing during critical seasons will reduce the risk ofGPC.

Note: Patients with pollen allergy should be instructednot to wear contact lenses during the hay fever season.

Bulbar Conjunctiva

Conjunctival Edema and Acute Chemosis

Symptoms: Severe itching and tearing; difficulty closingthe lids.

Clinical findings:Marked swelling of the conjunctiva thatmay project beyond the lid margin, with clear or san-guineous secretion. Mild proptosis.

Conjunctival edema in contact lens wearers is usuallydue to lens-cleaning solutions, or to wetting solutions orartificial tears that are supposed to enhance wearingcomfort. Acute conjunctival edemamay occur as early as

the fitting phase, particularly when relevant details ofthe case history are not obtained or disregarded, such asa previous episode of allergic blepharitis or conjunctivi-tis requiring treatment. Patients with certain types of al-lergies, for example to thiomersal, a common constitu-ent of eye drops and contact lens solutions, also tend todevelop acute conjunctival reactions when contactlenses are fitted.

Acute chemosis is a complication that usually ap-pears within a few minutes of the initial insertion of alens or the initial use of a lens care product or variety ofeye drops. Most of the affected patients were previouslytreated at some time with eye drops or ointments andwere presumably sensitized in this way. An adequatehistory helps to identify and prevent this problem:patients should be asked at the initial prefitting visitwhether they have ever had complications from the useof eyedrops or ointments, or difficulty tolerating them. Ifso, the risk is high that the initial insertion of contactlenses will cause marked conjunctival swelling withinminutes, so that the fitting will have to be terminated.

One can also use the Ophthalmotest to predict ad-verse reactions in advance and determine the offendingsolution constituent (cf. p. 80, 86).

Ophthalmologists periodically see an emergencycase of acute chemosis referred by a contact-lens-fittingoptician. The problem typically arises during a fittingsession, for example on initial application of a wettingsolution to improve lens-wearing comfort. Within a fewminutes, massive conjunctival swelling in both eyesmaycompletely occlude the palpebral fissure andmake it dif-ficult to close the lids. A retrospectively obtained historyusually reveals that the patient has been using non-prescription eye drops irregularly over the years,without medic