Caused by the type 1 herpes simplex virus, eye herpes (ocular herpes) is a common, recurrent viral infection affecting the eyes. This type of herpes virus can cause inflammation and scarring of the cornea that sometimes is referred to as a cold sore on the eye. Herpes of the eye can be transmitted through close contact with an infected person whose virus is active.
The National Eye Institute (NEI) says an estimated 400,000 Americans have experienced some form of ocular herpes, with close to 50,000 new and recurring cases occurring each year.
Forms of Eye Herpes
Ranging from a simple infection to a condition that can possibly cause blindness, there are several forms of eye herpes:
- Herpes keratitis is the most common form of eye herpes and is a viral corneal infection. Ocular herpes in this form generally affects only the top layer, or the epithelium, of the cornea, and usually heals without scarring.
- Stromal keratitis occurs when the infection goes deeper into the layers of the cornea. This can lead to scarring, loss of vision and, occasionally, blindness. Stromal keratitis is thought to be caused by a late immune response to the original infection. Although the condition is rare, the NEI reports that stromal keratitis is the leading cause of corneal scarring that subsequently causes blindness in the United States.
- Iridocyclitis is a serious form of eye herpes where the iris and surrounding tissues inside the eye become inflamed, causing severe sensitivity to light, blurred vision, pain and red eyes. Iridocyclitis is a type of uveitis that affects the more frontal portions of the inside of the eye.
When this infection occurs in the retina or the inside lining of the back of the eye, it is known as herpes retinitis.
Eye Herpes Symptoms and Signs
Various signs and symptoms are associated with an ocular herpes outbreak. You may experience inflammation of the cornea, which can cause an irritation or sudden and severe ocular pain. Also, the cornea can become cloudy, leading to blurry vision.
Other characteristics of eye herpes include:
- Eye herpes can cause inflammation and scarring of the eye’s clear surface (cornea).
- Swelling around the eyes
- Recurrent eye infections
- Foreign body sensation
- Eye redness
- Eye sores
- Watery eye discharge
- Sensitivity to light
Due to these numerous symptoms, your eye doctor may overlook an initial diagnosis of ocular herpes in its very early stages.
What Causes Eye Herpes?
Eye herpes is transmitted through contact with another person who is having an outbreak, or through self contact and contamination during an active herpes infection (such as a cold sore of the lip).
In an extreme case of damage from eye herpes, you may need a corneal transplant.
The herpes simplex virus enters the body through the nose or mouth and travels into the nerves, where it may be inactive. The virus can remain dormant for years and may never wake up.
The exact cause of an outbreak is unknown, but stress-related factors such as fever, sunburn, major dental or surgical procedures and trauma are often associated with incidents.
Once the initial outbreak occurs, the NEI says untreated eye herpes has about a 40-50 percent chance of returning. There is no specific time frame for ocular herpes to reappear; it could be several weeks or even several years following the original occurrence.
Although symptoms usually present themselves in only one eye, the virus possibly could affect the other eye as well.
What parts of the eyes are susceptible to herpes viruses?
All the parts of the eye are susceptible to infection. When any part of the eye is affected, it is referred to as herpes ophthalmicus.
The cornea is most often affected by HSV and HZV. Infection or inflammation of the cornea is known as keratitis. But these viruses can also affect the skin of the eyelids, the uveal tissue (iris and choroid), and the retina. For this reason, a thorough eye exam is recommended to assess the extent of eye involvement.
Who is at risk for herpes infections of the eyes?
Although a very large percentage of the population (85% or more) carries the HSV-1 virus, not everyone who carries the virus gets an eye infection.
When a person carrying the virus becomes immunocompromised (for example their immune system becomes weakened) due to HIV, medications (steroids, chemotherapy), age, and perhaps stress, the virus is more likely to become “active” and incite an eye infection.
However in many (if not most) cases of HSV infection, the frequency of eye infections appears to be random and not necessarily associated with episodes of stress or immune weakness.
In fact, studies have suggested that the particular subtype of HSV-1 that an individual harbors has as much to do with the frequency of eye infections as the individual’s immune status.
Eye Herpes Treatment
Treatment for eye herpes depends on where the infection is located in the eye — in the corneal epithelium, corneal stroma, iris, retina, etc. Some ocular herpes treatments could aggravate the outbreak and therefore should be considered on a case-by-case basis.
If the corneal infection is only superficial, it can normally be alleviated by using antiviral eye drops or ointments, or oral antiviral pills.
Zirgan (Sirion Therapeutics, Tampa, Fla.) was approved by the FDA in late 2009 as a topical antiviral treatment for eye herpes.
The treatment (ganciclovir ophthalmic gel, 0.15 percent), which became commercially available in the United States in late April 2010, involves instilling eye drops five times daily until the related corneal ulcer heals.
You should not wear contact lenses while undergoing treatment with Zirgan, which is marketed in Europe as Virgan.
An eye doctor may treat eye herpes by scraping away the infected corneal epithelial cells with a cotton swab or corneal “spatula” instrument. This is called debridement. Following debridement, a patch or soft contact lens might be needed to help the cornea to heal.
Steroid drops can help decrease inflammation and prevent corneal scarring when the infection appears deeper in the corneal layers. Steroid drops are almost always used in conjunction with and simultaneously with antiviral drops.
Steroid drops decrease the effectiveness of the eye’s immune system. Therefore, people with a history of ocular herpes should use only a steroid drop specifically prescribed by their eye doctor.
Steroid drops have been known to cause a recurrent eye herpes infection in susceptible patients. Also, an antibiotic eye drop along with a therapeutic contact lens may be used to prevent a secondary bacterial infection while the herpes eye infection is being treated.
Surgery is required if scarring occurs in the cornea and the treatments including the steroids do not help clear the center of the cornea. In cases where corneal scarring is permanent, a corneal transplant may restore vision.
Although eye herpes has no cure, treatment can help control outbreaks. Studies are underway to determine better methods for managing the disease.
As an example, a study reported in the September 2010 issue of Archives of Ophthalmology found that treating people with oral antiviral medication as a preventive measure significantly reduces the possibility that ocular herpes symptoms will recur.
How are herpes eye infections diagnosed?
Most of the time the diagnosis can be made based on the symptoms and the signs alone.
Herpes keratitis typically produces a distinct erosion of the outer layer of the cornea. This tiny erosion is called a “dendrite” and has a tree-branching pattern that can be seen by the examiner using an eye drop with a yellow dye and a blue light.
Under a slit-lamp microscope the eye doctor can look for further clues to distinguish between an HSV and an HZV keratitis, but in either case, the initial antiviral treatment is the same.
Close examination of the other eye tissues (including the skin, conjunctiva, anterior chamber, iris, retina, and more) also offers additional clues to make the diagnosis as well as helps tailor treatment. In questionable cases, a culture can be obtained to confirm the diagnosis.