The callous on the eye

There are two conditions which are often referred to as "the callous on the eye". At first glance, they appear similar, consisting of a raised, often yellowish or yellow-white patch, occasionally with irritated blood vessels, next to the cornea on the "white of the eye".

Pinguecula (ping gwek-u-la)

A very common lesion occurring from damage to the conjunctiva, the thin membrane which lines the sclera ("white of the eye") and the inside of the eyelids. It is often referred to as a "fatty degeneration" of the tissue. The fine, nearly transparent collagen fibers degenerate and are replaced by thicker, yellowish, more durable fibers and sometimes calcium crystals. This causes the elevated, yellow and sometimes glistening whitish area located next to the cornea. Basically, a callous! Often, there are no symptoms and the patient merely complains of the cosmetic concern.

If the area is significantly raised or has a lot of calcium crystals, the conjunctiva becomes further irritated as the eyelid crosses the area. Additionally, dry eye conditions cause even more lid-conjunctiva sensitivity and more symptoms, often resulting in increased yellowing and the appearance of irritated blood vessels.

It is believed that the primary cause of Pinguecula is exposure. We consider exposure to toxic vapors, salt water spray, exposure to the sun (ultraviolet radiation,) and damage to the conjunctiva from insufficient moisture and lubrication (tears) to be the primary causes. Pinguecula can appear after only a brief exposure to damaging chemicals or irritation. The tissue damage increases with continued exposure. It might take only a day or two to notice a new Pinguecula but weeks to resolve it.

Treatment

Treatment is to remove the source(s) of irritation and to provide moisture, lubrication and nutritional support so that the conjunctiva can heal. Often the condition can be reversed, if not too far advanced. Rapid response and intervention in the process results in less tissue damage and more rapid healing. Long standing Pinguecula are more difficult to resolve and may not respond as well to treatment.

Pterigium (terr-idgee-um)

In many ways, Pterigium have similar causes and symptoms to Pinguecula. But unlike the more simple Pinguecula, this condition is sometimes progressive and does involve the cornea, sometimes causing irreparable scarring and permanent damage. If allowed to continue to grow out onto the cornea, it can affect vision. This is seldom the case today where medical care is available as there is treatment to arrest the growth of the Pterigium.

It is believed that there is an underlying pathological cause to Pterigium. Unlike Pinguecula, the lesion develops a blood supply, is attached to the underlying structures, and grows new tissue which invades the adjacent cornea.