Most cases in the developed world occur in patients with fully established systemic infection with the spirochete of syphilis. Since most cases of syphilis are recognized and treated, it is not common. Interstitial keratitis is the most common cause of blindness in the world, with cases caused by trachoma and onchocerciasis (river blindness) being very common in endemic areas of Asia and Africa.

• eye pain
• photophobia
• excessive tearing

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 find and prove the causative infection.

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

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

Once corneal clarity is lost, corneal transplantation is required. The recovery is long and arduous, and not as successful as corneal transplantation in most other corneal diseases. The presence of blood vessels in the diseased cornea brings white cells to the transplant and makes the risk of rejection much higher.

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 avoidance of the underlying infection; and if infected, prompt and thorough treatment and follow up.