Interstitial keratitis is the inflammation of the tissue of the cornea, the clear window on the front of the eye. The condition can lead to vision loss.

Interstitial keratitis is a serious condition, in which blood vessels grow into the cornea. Such growth can cause loss of the normal transparency (clarity) of the cornea. This condition is often caused by infections and may cause severe visual problems.

Syphilis is the most common cause of interstitial keratitis, but rare causes include leprosy and tuberculosis. Most cases in the developed world occur in patients with fully established syphilis.

In the United States, most cases of syphilis are recognized and treated before this eye condition occurs. However, interstitial keratitis remains the most common cause of blindness in the world.

• Eye pain
• Excessive tearing
• Sensitivity to light (photophobia)

Interstitial keratitis can be easily diagnosed by physical examination of the eyes with slit lamp examination. Blood tests and chest x-rays will usually be needed to confirm the infection causing the condition.

The underlying disease must be treated. Treatment of the cornea with corticosteroid drops may minimize scarring, and help preserve the clarity of the cornea.

Once the clear covering of the cornea is gone, a corneal transplantation is required.

If interstitial keratitis is diagnosed early and treated effectively, the corneal clarity and thus good vision will be preserved.

Acorneal transplantation is not as successful for interstitial keratitis as it is for most other corneal diseases. The presence of blood vessels in the diseased cornea brings white blood cells to the newly transplanted cornea and increases the risk of rejection.

All patients with interstitial keratitis will be closely followed by an ophthalmologist and a medical specialist with expertise in the underlying disease. Any worsening pain, increasing redness or decreasing vision should be evaluated immediately. This is particularly crucial for patients with corneal transplants.

Prevention consists of avoiding the underlying infection, and if infected, receiving prompt and thorough treatment and follow-up.

Barnes SD, Pavan-Langston D, Azar DT. Microbial Keratitis. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 6th ed. London: Churchill Livingstone; 2005:chap 107.