Interstitial keratitis is chronic, nonulcerative inflammation of the mid-stroma (the middle layers of the cornea) that is sometimes associated with uveitis. The cause is usually infectious. Symptoms are photophobia, pain, lacrimation, and vision blurring. Diagnosis is by slit-lamp examination and serologic tests to determine the cause. Treatment is directed at the cause and may require topical corticosteroids.
Interstitial keratitis, a manifestation of certain corneal infections, is rare in the US. Most cases occur in children or adolescents as a late complication of congenital syphilis (see Congenital Syphilis). Ultimately, both eyes may be involved. A similar but less dramatic bilateral keratitis occurs in Cogan syndrome (see Cogan Syndrome), Lyme disease (see Lyme Disease), and Epstein-Barr virus infection. Rarely, acquired syphilis, herpes simplex, herpes zoster, or TB may cause a unilateral form in adults.
Symptoms and Signs
Photophobia, pain, lacrimation, and vision blurring are common. The lesion begins as patches of inflammation in the mid-stroma that cause opacification. Typically with syphilis and occasionally with other causes, the entire cornea develops a ground-glass appearance, obscuring the iris. New blood vessels grow in from the limbus (neovascularization) and cause orange-red areas (salmon patches). Anterior uveitis and choroiditis are common in syphilitic interstitial keratitis. Inflammation and neovascularization usually begin to subside after 1 to 2 mo. Some corneal opacity usually remains, causing mild to moderate vision impairment.
The specific etiology must be determined. The stigmas of congenital syphilis, vestibuloauditory symptoms, history of an expanding rash, and tick exposure support specific etiologies. However, all patients should have serologic testing, including all of the following:
Patients with negative serologic test results may have Cogan syndrome, an idiopathic syndrome consisting of interstitial keratitis and vestibular and auditory deficits. To prevent permanent vestibuloauditory damage, symptoms of hearing loss, tinnitus, or vertigo require urgent referral to an otolaryngologist.
Keratitis may resolve with treatment of the underlying condition. Additional topical treatment with a corticosteroid, such as prednisolone 1% qid, is often advisable. An ophthalmologist should treat these patients.
Last full review/revision September 2014 by Melvin I. Roat, MD, FACS
Content last modified October 2014