Contact Lens-induced
Conjunctival Lesions

BY ROBERT CAMPBELL, M.D. & PATRICK CAROLINE, C.O.T., F.A.A.O.
SEPT. 1996

Perhaps you have examined long-term rigid lens wearers who have developed elevated, wedge-shaped, conjunctival masses within the interpalpebral space. The base of the wedge is always positioned at the limbus, and the apex extends toward the lateral canthus (Figs. 1 & 2).

FIGS. 1 & 2: INTERPALPEBRAL CONJUNCTIVAL LESIONS, OR CONTACT LENS-INDUCED CONJUNCTIVAL XEROSIS

The conjunctival lesions can be located on the nasal or temporal side of the cornea and are often asymmetric. They are pigmented slightly brown and have lost their normal luster, with the conjunctival epithelium appearing keratinized.

Treatment consists of managing the patient's symptoms, which can range from cosmetic concerns only to a chronic foreign body sensation, although most patients are asymptomatic. The cause of these lesions is still unclear, but a review of similar conjunctival masses provides some insight into the etiology of the condition.

BITOT SPOTS

One such condition was first described by Hubbenet, a chief medical officer in the French army. In 1860, he observed elevated, triangular conjunctival lesions and night blindness in prisoners of the Crimean war.

Three years later, Charles Bitot described the same clinical condition in detail. In his paper, Bitot cited a triangularly shaped collection of brilliant white dots producing a pearly, foamy conjunctival mass adjacent to the cornea. He noted that the conjunctiva around the spot had "lost its moisture, becoming dry and thickened."

Today, classic Bitot spots are often associated with a dietary vitamin A deficiency. They have also been noted in pellagra and other nutritional deficiencies. Histologically, the spots reveal a thickening and keratinization of the conjunctival epithelium, and the organism corynebacterium xerosis is often present in the lesion.

The location of the spots within the interpalpebral space indicates that exposure also plays a role in their formation. A 1957 report by Appelmans described the development of a typical Bitot spot on the exposed portion of the conjunctiva at the 12 o'clock position in a case of unilateral coloboma of the upper lid.

CONJUNCTIVAL XEROSIS

In 1971, Lowther, Bailey and Hill described a condition in rigid contact lens wearers that they called conjunctival xerosis. These were slightly elevated bulbar conjunctival lesions along the nasal and temporal 180⁰ meridian. The most striking feature of these lesions was their complete resolution within a few days of discontinuing lens wear, and their recurrence within one week of resuming lens wear. At that time, lens design variations, i.e, base curve, diameter or thickness, had no effect on the condition.

WHAT ARE THESE LESIONS

If chronic conjunctival lesions aren't Bitot spots (nutritional deficiency-induced) or conjunctival xerosis (rapid, resolving and recurring lesions), then what are they?

We think they are both. They most likely represent classic Bitot spots as described by Appelmans in 1957 (secondary to long-term exposure and chronic conjunctival dryness) which result in a long-term conjunctival xerosis (complete with possible epidermidalization, acanthosis, dyskeratosis and keratinization of the conjunctival epithelium).

Therefore, "contact lens-induced conjunctival xerosis" may be the term that best describes these chronic, elevated lesions noted in long-term rigid lens wearers. CLS

Dr. Campbell is medical director of the Park Nicollet Contact Lens Clinic & Research Center, Minnetonka, Minn. Patrick Caroline is an assistant professor of optometry at Pacific University, Forest Grove, Ore., and director of contact lens research at Oregon Health Sciences University, Portland, Ore.