(See also Introduction to Corneal Disorders.)
Interstitial keratitis is rare in the United States. Most cases occur in children or adolescents as a complication of congenital syphilis. Other causes of interstitial keratitis include Cogan syndrome, Lyme disease, Epstein-Barr virus, acquired syphilis, herpes simplex, varicella-zoster virus, and tuberculosis.
Doctors suspect interstitial keratitis when they see an affected cornea in a person who also has a history of an infection such as syphilis. To examine the cornea, they usually use a slit lamp (an instrument that enables doctors to examine the eye under high magnification).
Blood tests and other tests for syphilis, Lyme disease, and the Epstein-Barr virus are also done. People with interstitial keratitis and normal blood tests should be evaluated for Cogan syndrome.