Conjunctival Degeneration and Aging Changes

Conjunctival Degeneration and Aging Changes

Pingueculum

Definition

Harmless grayish yellow thickening of the conjunctival epithelium in the palpe-bral fissure.

Epidemiology: Pinguecula are the most frequently observed conjunctivalchanges.

Etiology: The harmless thickening of the conjunctiva is due tohyalinedegeneration of the subepithelial collagen tissue. Advanced age and exposureto sun, wind, and dust foster the occurrence of the disorder.

Symptoms: Pingueculum does not cause any symptoms.

Diagnostic considerations: Inspection will reveal grayish yellow thickeningat 3 o’clock and 9 o’clock on the limbus. The base of the triangular thickening (often located medially) will be parallel to the limbus of the cornea; the tip will be directed toward the angle of the eye (Fig. 4.2).

Differential diagnosis: A pingueculum is an unequivocal finding.

Treatment: No treatment is necessary.

Pterygium

Definition  Triangular fold of conjunctiva that usually grows from the medial portion of the palpebral fissure toward the cornea.

Epidemiology: Pterygium is especially prevalent in southern countries dueto increased exposure to intense sunlight.

Etiology: Histologically, a pterygium is identical to a pinguecula. However, itdiffers in that it can grow on to the cornea; the gray head of the pterygium will grow gradually toward the center of the cornea (Fig. 4.3a). This progression is presumably the result of a disorder of Bowman’s layer of the cornea, which pro-vides the necessary growth substrate for the pterygium.

Symptoms and diagnostic considerations: A pterygium only producessymptoms when its head threatens the center of the cornea and with it the visual axis (Fig. 4.3b). Tensile forces acting on the cornea can cause severe corneal astigmatism. A steadily advancing pterygium that includes scarred conjunctival tissue can also gradually impair ocular motility; the patient will then experience double vision in abduction.

Differential diagnosis: A pterygium is an unequivocal finding.

Treatment: Treatment is only necessary when the pterygium produces thesymptoms discussed above. Surgical removal is indicated in such cases. The head and body of the pterygium are largely removed, and the sclera is left open at the site. The cornea is then smoothed with a diamond reamer or an excimer laser (a special laser that operates in the ultraviolet range at a wavelength of 193 nm).

Clinical course and prognosis: Pterygia tend to recur. Keratoplasty is indi-cated in such cases to replace the diseased Bowman’s layer with normal tissue. Otherwise the diseased Bowman’s layer will continue to provide a growth substrate for a recurrent pterygium.

Pseudopterygium

A pseudopterygium due to conjunctival scarring differs from a pterygium in that there are adhesions between the scarred conjunctiva and the cornea and sclera. Causes include corneal injuries and/or chemical injuries and burns. Pseudopterygia cause pain and double vision. Treatment consists of lysis of the adhesions, excision of the scarred conjunctival tissue, and coverage of the defect (this may be achieved with a free conjunctival graft harvested from the temporal aspect).

Subconjunctival Hemorrhage

Extensive bleeding under the conjunctiva (Fig. 4.4) frequently occurs with conjunctival injuries (for obtaining a history in trauma cases, see conjunctival laceration). Subconjunctival hemorrhaging will also often occur spontaneously in elderly patients (as a result of compromised vascular struc-tures in arteriosclerosis), or it may occur after coughing, sneezing, pressing, bending over, or lifting heavy objects. Although these findings are often very unsettling for the patient, they are usually harmless and resolve spon-taneously within two weeks. The patient’s blood pressure and coagulation status need only be checked to exclude hypertension or coagulation disorders when subconjunctival hemorrhaging occurs repeatedly.

Calcareous Infiltration

A foreign-body sensation in the eye is often caused by white punctate concre-ments on the palpebral conjunctiva. These concrements are the calcified con-tents of goblet cells, accessory conjunctival and lacrimal glands, or mei-bomian glands where there is insufficient drainage of secretion. These cal-careous infiltrates can be removed with a scalpel under topical anesthesia.

Conjunctival Xerosis

Definition

Desiccation of the conjunctiva due to a vitamin A deficiency.

Epidemiology: Due to the high general standard of nutrition, this disorder isvery rare in the developed world. However, it is one of the most frequent causes of blindness in developing countries.

Etiology: Vitamin A deficiency results in keratinization of the superficialepithelial cells of the eye. Degeneration of the goblet cells causes the surface of the conjunctiva to lose it luster (Fig. 4.5a). The keratinized epithelial cells die and are swept into the palpebral fissure by blinking, where they accumu-late and create characteristic white Bitot’s spots (Fig. 4.5b). Xerosis bacteria frequently proliferate.

Treatment and prognosis: The changes disappear after local and systemicvitamin A substitution. Without vitamin A substitution, the disorder will lead to blindness within a few years.