You Looking at Me?

By Peter Galvin, MD

A while ago I came across a clinical vignette in “The New England Journal of Medicine” that was interesting, so I thought I would share it with you. It involved a 53-year-old man who was admitted to a hospital following a fall which resulted in a fractured femur (thigh bone). On exam, incidentally noted was abnormal indentation of his lower eyelids (see photo). He had a history of bilateral corneal transplantations owing to increasing visual impairment and difficulty fitting contact lenses. In recent years, his vision worsened, and his fall occurred because of difficulty seeing a stairway. The eyelid abnormality was noticed by a resident during rounds when the patient was asked to look down. A diagnosis of keratoconus was made. Following surgical repair of his femoral fracture, he was referred to the ophthalmology department for repeat corneal transplantation.

Keratoconus (ker-uh-toe-KOH-nus) is an eye condition in which the cornea – the clear, dome-shaped front covering of the eye – gets thinner and gradually bulges outward into a cone shape. The cone-shaped cornea causes blurred vision and may cause sensitivity to light and glare. It usually begins between the late teens and 30 years of age. It commonly progresses slowly over a period of 10 years or longer. In the early stages, vision is often correctable with glasses or contacts, however later on the patient must be fitted with rigid, gas-permeable contact lenses or other types of lenses, for example the larger scleral lenses. Not infrequently, vision becomes so poor that a corneal transplant is required, as it was in our case patient. A procedure called corneal collagen cross-linking may help to slow or stop keratoconus from progressing, thereby negating the need for corneal transplantation.

The cause of keratoconus is unknown, although genetic and environmental factors are thought to be involved. About one in 10 people with it have a parent with it. As the disease progresses, symptoms may include blurred or distorted vision, light sensitivity which may cause problems driving at night, a need for frequent eyeglass prescription changes, and sudden worsening or clouding of vision. A diagnostic sign is the indenting of the lower eyelid when the patient looks down. It is caused by the bulging, cone-shaped cornea, as you can see in the photo. This is called Munson’s sign, named after American ophthalmologist Edwin Sterling Munson (5/8/1870 – 2/2/1958). Please tell me you didn’t think it was named for Thurmon Munson!

Risk factors for keratoconus include having a family history of it, repeatedly vigorously rubbing your eyes, and having certain conditions such as retinitis pigmentosa, Down syndrome, Ehlers-Danlos syndrome, Marfan syndrome, hay fever, and asthma. Sometimes in keratoconus, the cornea may quickly swell and cause sudden vision reduction and scarring or the cornea. This is due to a condition where the inside lining of the cornea, called Descemet’s membrane, breaks down. This causes fluid to enter the cornea, a condition known as hydrops. The swelling may go down on its own, but scarring may occur and severely reduce vision.

An ophthalmologist can diagnose keratoconus early in the disease and can often prevent it from worsening, which is why regular eye checkups by an ophthalmologist, even and especially for children and teenagers, are important.

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