What Is Herpes Simplex?

Herpes simplex virus (HSV) is a virus that infects the skin, mucous membranes and nerves. There are two major types of HSV. Type 1 is the most common and is responsible for herpes simplex eye disease and the familiar "cold sore" or "fever blister". Type 2 is responsible for sexually transmitted herpes and rarely causes eye disease.
An original infection with HSV type 1 occurs in 90 percent of the population, usually during childhood or adolescence. The infection, sometimes only a mild sore mouth or throat, comes from close personal contact with an infected person and usually passes without notice. After the original infection, the virus goes into a quiet or dormant period, living in nerve cells that supply the skin or eye. Occasionally, the virus reactivates and causes a recurrent "cold sore" or "fever blister".

Herpes Simplex Eye Disease

The most common herpes simplex eye disease caused by HSV type 1 is a recurrent eye infection of the cornea, the clear front window of the eye, and this can potentially threaten sight. The infection varies in duration, severity and response to treatment.

The disease usually begins on the surface of the cornea. The eye turns red and is sensitive to light. For most people this will be the only episode. Unfortunately, one out of four people who have a corneal infection are likely to have a recurrence within two years.

The process may go deeper into the cornea and cause permanent scarring or inflammation inside the eye. Chronic ulcers, which are sometimes very difficult to heal, may also develop on the cornea. HSV eye disease usually occurs in only one eye and rarely spreads to the other eye. Spreading the infection to another person is unlikely.

Treatment

Treatment depends on the extent of the disease. Antiviral eye medications are commonly used and may need to be applied frequently. At times it may be necessary to mechanically scrape the surface of the cornea, to patch the eye, or to use a variety of medications. These may need to be continued for many months. In cases of severe scarring and vision loss, a corneal transplant may be required.