In May 2006, the U.S. Food and Drug Administration approved a new vaccine for people over the age of 60 who have had chickenpox. Why is this good news for your vision? Because the herpes virus that causes chickenpox also causes shingles, a very painful rash that could break out on your face and threaten your vision.

Most people associate herpes viruses only with genital infections. But within the herpes family are eight types of the virus, three of which can affect the eye: varicella zoster virus (VZV), which causes chickenpox and also shingles, and herpes simplex virus-1 and -2 (HSV-1 and HSV-2).

Herpes Zoster Ophthalmicus-- The infection that results from VZV is called herpes zoster, which causes the blistery rash commonly known as shingles. Although HSV- 1 and -2 infections are more prevalent overall, shingles caused by VSV is more common among the elderly and those with weakened immune systems. In fact, people over age 80 face five times the risk of people between ages 20 and 40 for having an episode of shingles.

Shingles affects only people who have already had chickenpox, a common viral infection that usually manifests itself in childhood when someone first contracts the herpes zoster virus. During the intervening years, the herpes virus itself remains dormant in nerve bundles at the back of the spine called dorsal root ganglia. The period of dormancy can last for decades until aging, stress, illness, or certain medications reactivate the virus, which erupts in the rash called shingles (as opposed to chickenpox).

The shingles rash usually affects only one side of the body, frequently the trunk or the face. If the reawakened virus travels down nerves in the head, the resulting facial shingles -- especially on the forehead, nose, or eyelid -- are more likely to lead to herpes zoster ophthalmicus (HZO), the form that affects the eye.

The initial symptoms of HZO may include a red eye, fever, face and neck pain, or a rash on the forehead, eyelid, or skin surrounding the eye. If the infection further invades corneal tissue -- about a 40–50% risk -- this can lead to keratitis (inflammation and scarring of the cornea), inflammation of the retina or optic nerve, glaucoma, or cataracts, any of which may also result in blurred vision or blindness. The infection may leave the cornea without feeling or less sensitive to substances that might touch it, such as debris, eyelashes, or dust, upping the risk of subsequent injury.

Taken early in the course of HZO, oral antiviral drugs -- valacyclovir (Valtrex), famciclovir (Famvir), or acyclovir (Zovirex) -- can halve the chance of serious complications. Your ophthalmologist may also prescribe antibiotic, anti-inflammatory, or lubricating eyedrops or oral pain medication. With any luck, however, the vaccine will have prevented your need for any of this. It reduces by at least one half the incidence of shingles itself and the degree of pain and discomfort involved. The vaccine appears effective for at least four years after inoculation.

Ocular Herpes -- HSV-1 and HSV-2 can cause ocular herpes, a recurrent infection and the most common cause of corneal blindness in the United States. Although HSV-2, the sexually transmitted virus known as genital herpes, can cause ocular herpes, HSV-1, transmitted by body fluids such as saliva, is usually the culprit. Once people develop ocular herpes, they have a 50% chance of recurrence within weeks or years, possibly triggered by fever, stress, sunlight, or eye injury. Approximately 400,000 Americans have ocular herpes, with 50,000 new or recurring cases every year. In 12% of cases, both eyes are affected.

An infection with HSV-1, also responsible for cold sores, usually erupts first in infants and young children. The initial outbreak is often mild -- a sore throat or mouth -- but can also involve the eye, inflaming the inside and outside of the eyelid and the surface of the eye. Like varicella zoster, HSV-1 and -2 can retire within the ganglia for years.

Subsequent infections can produce a range of eye difficulties, from mild blisters on the eyelid and surrounding skin (HSV blepharitis) to lesions on the eye surface, inflaming the cornea (HSV keratitis) and potentially causing inflammation inside the eye (uveitis). Symptoms include blurred or diminished vision, sensitivity to light, eye pain, redness, or tearing.

Bottom-line advice: Evicting either herpes simplex virus for good isn’t possible, but you can protect yourself from ocular herpes through simple habits: Avoid touching your eyes when you have a cold sore or blisters, and wash your hands before putting in your contact lenses. If you do get even a mild eye irritation, forget about the over-the-counter medications and instead check with your eye doctor. Used in the wrong way, some medications only make the condition worse.