Keratitis is an inflammation of the cornea of the eye. Keratitis is associated with a number of diseases and infections. Viral infections are the most common cause of keratitis, with the herpes simplex virus topping the list. Other viruses that infect the cornea include the chickenpox virus (varicella zoster) and a virus that causes the common cold (adenovirus).
Only one eye is usually affected when the infection is caused by herpes simplex. The symptoms include redness, sensitivity to light, pain, a sensation that there is sand in the eye, watery eye and blurred vision.
Left untreated, the herpes simplex keratitis can be quite serious, especially in people with a depressed immune system, and can lead to visual impairment.
Prescription antiviral eye drops will reduce the duration and severity of the symptoms, but won't cure the infection. Because the virus can "hibernate" in nerve tissue, many people have repeat bouts of keratitis.
I know of no over-the-counter drugs that have been shown to be useful for herpes keratitis. Over 20 years ago there were a couple of case reports of people getting relief of their symptoms early when they were treated with cimetidine (also known as Tagamet). Cimetidine, which is now available over the counter, was never shown to be effective in the clinical studies. The idea that cimetidine might work was not farfetched. Cimetidine is known to increase the activity of specialized immune system blood cells called T-cells. However, I need to point out that there are no studies that have shown this to be of value in people with herpes infections. A prescription antiviral eye drop or ointment is normally used to treat herpes keratitis.
