Herpes simplex eye infection is caused by a type of herpes simplex
virus. An episode often clears without any permanent problem. However,
in some cases the infection causes scarring to the cornea. This can lead
to permanent loss of vision. Prompt treatment with antiviral eye
ointment or drops helps to prevent corneal scarring.
There are two types of herpes simplex virus. Type 1 virus is the usual cause of cold sores around the mouth, and herpes simplex infection in the eye. Type 2 virus is the usual cause of genital herpes. It rarely causes cold sores or eye infections.
Following the primary infection, the virus stays with you for life. It stays inactive (dormant) in the root of a nerve in the face (the trigeminal nerve).
In most cases, the infection is just in the top (superficial) layer
of the cornea. This is called epithelial keratitis. Sometimes deeper
layers of the cornea are involved. This is called stromal keratitis.
This is more serious, as it is more likely to cause scarring of the
cornea.
Other parts of the eye are sometimes affected. A minor and temporary inflammation of the conjunctiva (conjunctivitis) or eyelids (blepharitis) may occur with active infection, often at the same time as the cornea is infected. Deeper structures such as the retina or iris may also sometimes be affected.
A doctor will usually examine your eye with a magnifier. They may
also put some stain on the front of your eye to show up any irregular
areas on the cornea. With a herpes simplex infection they will often see
a small ulcer (erosion) on the cornea. The typical ulcer which develops
is called a dendritic ulcer. Dendritic means many fingered. The ulcer
is not round with a smooth edge but like a tree with many finger-like
branches.
If your doctor suspects a herpes eye infection you will usually be referred urgently to an eye specialist. A specialist will do a detailed magnified examination of the eye. This is to confirm the diagnosis and to determine whether the infection is in the top layer of the cornea (epithelial keratitis), or if the deeper layers are involved (stromal keratitis).
There are two types of herpes simplex virus. Type 1 virus is the usual cause of cold sores around the mouth, and herpes simplex infection in the eye. Type 2 virus is the usual cause of genital herpes. It rarely causes cold sores or eye infections.
The first time you are infected is called the primary infection. Many people become infected with this virus, often during childhood. (The herpes simplex virus can pass through the moist skin that lines the mouth. It is commonly passed on by close contact such as kisses from a family member who has a cold sore.) In many people the primary infection does not cause any symptoms, although in some cases symptoms do occur.
Following the primary infection, the virus stays with you for life. It stays inactive (dormant) in the root of a nerve in the face (the trigeminal nerve).
- In many people, the virus remains permanently inactive and causes no problems.
- In some people, the virus activates and multiplies from time to
time. Virus particles then travel down the nerve to cause episodes of
active infection with symptoms.
- In most of these cases, the virus travels down a branch of the nerve to the mouth to cause cold sores. (See leaflet called 'Cold Sores' for details.)
- In some of these cases, the virus travels down a branch of the nerve to the eye to cause episodes of active eye infection. The rest of this leaflet is about herpes simplex infection of the eye.
Which part of the eye is affected by herpes simplex infection?
The common situation is for the cornea to become infected. The cornea is the transparent window of the eye. Infection of the cornea is called keratitis.Other parts of the eye are sometimes affected. A minor and temporary inflammation of the conjunctiva (conjunctivitis) or eyelids (blepharitis) may occur with active infection, often at the same time as the cornea is infected. Deeper structures such as the retina or iris may also sometimes be affected.
Who gets herpes simplex infections of the eye?
About 1-2 people in 1,000 will develop at least one episode of active herpes simplex eye infection at some stage in their life. The most common time for a first active infection is between the ages of 30-40. Often people who get active eye infection will have had previous cold sores during their lifetime. Herpes simplex eye infections may also be more common in people who wear contact lenses.What are the symptoms and signs of active infection?
Most episodes of active infection are due to a reactivation of the virus at some point, often years after a primary infection. Symptoms include:- Redness of the eye - mainly around the cornea.
- Ache or pain in the eye.
- Photophobia (discomfort when opening the eyes in bright light).
- Watering of the eye.
- Blurring of vision.
How is herpes simplex eye infection diagnosed?
If your doctor suspects a herpes eye infection you will usually be referred urgently to an eye specialist. A specialist will do a detailed magnified examination of the eye. This is to confirm the diagnosis and to determine whether the infection is in the top layer of the cornea (epithelial keratitis), or if the deeper layers are involved (stromal keratitis).
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