infections

Herpes simplex eye infections are usually caused by the herpes simplex virus type 1 (HSV-1). The HSV-1 virus can also cause cold sores on your face. Rarely, the HSV-1 virus can also cause genital herpes.

Herpes simplex eye infection can also be caused by the herpes simplex virus type 2 (HSV-2). HSV-2 is the virus that can cause genital herpes. Rarely, the HSV-2 virus can also cause cold sores on your face.

What triggers a herpes simplex eye infection?

If you have been exposed to the herpes simplex virus, it will usually remain dormant (inactive). However, it can be triggered by certain factors. This can then cause cold sores and eye infections.

Trigger factors include:

• having other illnesses or injuries,
• exposure to strong sunlight,
• having a fever (high temperature),
• exposure to cold winds,
• stress, and
• having your period (in women).

Having a weakened immune system can also trigger regular cold sores or herpes simplex eye infections. For example, if you have HIV or are receiving chemotherapy treatment.

It's important to speak with your GP if you have symptoms of a herpes simplex eye infection. The infection can cause permanent damage to your eyes if it is not treated.

Your GP

Your GP will ask you about your symptoms and examine your eyes to rule out any other conditions.

They may put a harmless dye into your eye so they can see any irregular areas or injury. This is called fluorescein staining.

Your GP may also test your vision using a Snellen chart (a chart with blocks of letters that gradually get smaller).

Your eye specialist

If your GP thinks that you may have a herpes simplex eye infection, they will send you to an eye specialist (ophthalmologist) who will see you on the same day.

This is because herpes simplex infection is difficult to diagnose without specialist knowledge and equipment. It can also permanently affect your eyesight if you do not have treatment quickly.

In addition to the tests above, your eye specialist may also take a sample of the fluid (tears) from your eye so it can be tested in a laboratory.

Symptoms of a herpes simplex eye infection include:

• eye redness (red eye),
• moderate to severe pain in or around your eye,
• sensitivity to light (photophobia),
• a watery eye, and
• vision problems (for example, blurred vision).

You may also feel generally unwell, or have a fever (high temperature).

Sometimes, you might not have any noticeable symptoms if you have a herpes simplex eye infection.

Treatment of a herpes simplex eye infection depends on how bad the infection is, and what part of the eye is affected.

Sometimes, your eye specialist may advise no treatment. If this is the case you may be asked to see your eye specialist regularly to make sure that the infection clears up naturally and does not get worse.

Eye drops and ointments

Your eye specialist may prescribe eye drops or eye ointment that contain either:

• antiviral medicine, or
• a corticosteroid (a type of steroid found naturally in your body).

Sometimes, your eye specialist may advise that you take antiviral and steroid eye drops or ointment at the same time. This is because some research suggests that this can clear herpes simplex eye infections more quickly.

Eye cleaning

Before you start treatment with eye drops or ointment, your eye specialist may 'clean' your eye by gently scraping infected cells from the surface of your eye. This is also known as 'debridement'.

This will be carried out under local anaesthetic so you do not feel any pain while it is being done.

Oral medicine

Oral (by mouth) medicine is not normally used to treat a herpes simplex eye infection.

However, it may be prescribed after treatment to stop the infection coming back. You may have to keep taking it for up to a year after the infection has gone.

Wearing contact lenses

It's best not to wear contact lenses until you have finished treatment and the symptoms have gone completely.