Interstitial keratitis is a particular type of eye inflammation with a variety of causes, from syphilis infection to rheumatoid arthritis. This affects the layer of the eye responsible for allowing light into the pupil. Symptoms include pain in the eye, a deterioration in vision and abnormally high tear production. Treatment options depend on the initial cause of the disease, but range from antibiotic eye drops to surgery.
Keratitis is a medical term that simply describes an inflammation of the cornea. The cornea is the see-through layer of tissue at the front of the eye, which covers the pupil and the colored part of the eye. Interstitial refers to a situation where a medical condition develops in the gap between tissues. In the case of interstitial keratitis, these gaps are the spaces between the cells of the cornea.
Inside these gaps, cells grow abnormally, and blood vessels develop to feed these cells. Inflammation occurs, and the cornea can become scarred and lose its transparency. As light normally passes through the corneal layer, this loss of transparency can blur the vision. The inflammation can also produce symptoms like pain, too much tear production and an abnormal sensitivity to light.
This condition can arise from infection, but it can also be caused by an autoimmune problem, where the body produces inflammation for no beneficial reason. Syphilis infection is the most common cause of interstitial keratitis, though, and it can also affect babies whose mothers have syphilis. Other infectious causes of the condition include leprosy, Lyme Disease and tuberculosis.
Rheumatoid arthritis, sarcoidosis and a condition called Cogan syndrome are the most common autoimmune causes of interstitial keratitis. These conditions produce inflammation where no infection occurs, causing the same symptoms as inflammation of the eye due to infection. Whatever the original cause of the eye problem is, though, an ophthalmologist can identify interstitial keratitis through a special eye examination technique called a slit-lamp examination.
Once the problem is identified, the options for treatment depend on the cause. Bacterial infections like syphilis can respond well to antibiotic regimens, whereas viral infections require different medications. Corticosteroids, which are drugs that mimic the effects of natural immune system hormones, can help reduce the inflammation and pain, and prevent scarring.
These are also the primary drugs used in the treatment of interstitial keratitis caused by autoimmune disease. Severe cases, with scarring to the cornea, may require surgery to replace the cornea, although this is normally a last resort option. As interstitial keratitis is often caused by infection, sexual partners of the affected person should also be checked for infection and treated if necessary to prevent the development of the condition.