Problems with Contact Lenses

Etiology: These problems occur either with poorly seated rigid contact lenses that rub on the surface of the cornea or from overwearing soft contact lenses.

— Giant papillae from contact lens incompatibility.

— Giant papillae from contact lens incompatibility.

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Fig. 5.12 Wartlike protrusions of connective tissue on the pal-pebral conjunctiva due to contact lens or preservative incompatibility (with simple eversion of the upper eyelid).

Fig. 5.12 Wartlike protrusions of connective tissue on the pal-pebral conjunctiva due to contact lens or preservative incompatibility (with simple eversion of the upper eyelid).

If contact lenses are worn for extended periods of time despite symptoms, severe inflammation, corneal ulceration, and vascularization of the corneal periphery may result.

Symptoms: Patients find the contact lenses increasingly uncomfortable and notice worsening of their vision. These symptoms are especially pronounced after removing the contact lenses as the lenses mask the defect in the corneal epithelium.

Diagnostic considerations: The ophthalmologist will detect typical corneal changes after applying fluorescein dye (Fig. 5.11 e). Keratoconjunctivitis on the superior limbus with formation of giant papillae, wart-like protrusions of connective tissue frequently observed on the superior tarsus (Fig. 5.12), are signs of contact lens or preservative incompatibility.

Treatment: The patient should temporarily discontinue wearing the contact lenses, and inflammatory changes should be controlled with steroids until the irritation of the eye has abated.

H Protracted therapy with topical steroids should be monitored regularly by an ophthalmologist as superficial epithelial defects heal poorly under steroid therapy. Protracted high-dosage steroid therapy causes a secondary increase in intraocular pressure and cataract in one-third of all patients.

The specific ophthalmologic findings will determine whether the patient should be advised to permanently discontinue wearing contact lenses or whether changing contact lenses and cleaning agents will be sufficient.

5.5 Noninfectious Keratitis and Keratopathy 143 5.5.5 Bullous Keratopathy Definition

Opacification of the cornea with epithelial bullae due to loss of function of the endothelial cells.

Epidemiology: Bullous keratopathy is among the most frequent indications for corneal transplants.

Etiology: The transparency of the cornea largely depends on a functioning endothelium with a high density of endothelial cells (see Transparency). Where the endothelium has been severely damaged by inflammation, trauma, or major surgery in the anterior eye, the few remaining endothelial cells will be unable to prevent aqueous humor from entering the cornea. This results in hydration of the cornea with stromal edema and epithelial bullae (see Figs. 5.13 a and b). Loss of endothelial cells may also have genetic causes (see Fuchs' endothelial dystrophy).

Symptoms: The gradual loss of endothelial cells causes slow deterioration of vision. The patient typically will have poorer vision in the morning than in the evening, as corneal swelling is greater during the night with the eyelids closed.

Diagnostic considerations: Slit lamp examination will reveal thickening of the cornea, epithelial edema, and epithelial bullae.

Differential diagnosis: Bullous keratopathy can also occur with glaucoma. However, in these cases the intraocular pressure is typically increased.

Treatment: Where the damage to the endothelial cells is not too far advanced and only occasional periods of opacification occur (such as in the morning), hyperosmolar solutions such as 5% Adsorbonac can improve the patient's eyesight by removing water. However, this is generally only a temporary solution. Beyond a certain stage a corneal transplant (penetrating keratoplasty; see p. 152) is indicated.

144 5 Cornea Bullous keratopathy. -

a Corneal edema due to a lack of endothelial cells.

a Corneal edema due to a lack of endothelial cells.

b Image obtained by specular microscopy shows destruction of the endothelial cells (right side of image). In comparison, the left side (a wide-angle view) and the middle (magnified view) of the image show an intact en-dothelium with a clearly visible honeycomb structure. The actual size of the area shown on the left side of the image is about 0.5 mm2.

5.6 Corneal Deposits, Degenerations, and Dystrophies

As bradytrophic avascular tissue, the cornea is particularly susceptible to deposits of foreign material and degeneration (see 5.6.2).

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