(See also Introduction to Corneal Disorders.)
Cogan syndrome is an autoimmune disease that causes inflammation of the eyes, the ears, and sometimes the blood vessels (vasculitis). An autoimmune disorder is a malfunction of the body's immune system that causes the body to attack its own tissues. When Cogan syndrome affects the blood vessels, it can cause a life-threatening problem called aortitis.
Cogan syndrome can affect different parts of the eye, including the cornea. The cornea is the clear layer in front of the iris and pupil. It protects the iris and lens and helps focus light on the retina. It is composed of cells, protein, and fluid. The cornea looks fragile but is almost as stiff as a fingernail. However, it is very sensitive to touch.
People can develop eye pain, decreased vision, increased sensitivity to bright light, and redness of the eye. If the ears are affected, people can develop hearing loss, ringing in the ears, and vertigo. If the blood vessels are affected, people can have heart murmurs and claudication (pain in the limbs during physical activity).
The diagnosis of Cogan syndrome is suspected when a person has symptoms of corneal inflammation without any known cause. A slit lamp, an instrument that enables a doctor to examine the eye under high magnification, is usually used to examine the cornea.
Blood tests for syphilis, Lyme disease, and the Epstein-Barr virus are done to rule out these diseases, which may have symptoms similar to those of Cogan syndrome.
A corticosteroid eye drop is given to decrease inflammation in the cornea. If there is no improvement, if the inflammation is very deep, if the ear is affected, or if blood vessel inflammation (vasculitis or aortitis) is detected, corticosteroids are given by mouth. Sometimes people are treated with other drugs such as cyclophosphamide, methotrexate, cyclosporine, or infliximab.