Herpes simplex eye infections are eye infections caused by the herpes simplex virus – the same virus group that can cause cold sores and genital herpes.
The infection can cause redness, inflammation and pain in or around the eye, and sensitivity to light (see Herpes simplex eye infections - symptoms, for more information).
Sometimes people can have an active herpes simplex eye infection without any noticeable symptoms.
Who is affected
Herpes simplex eye infections are quite common and usually affect the middle-aged.
A herpes simplex eye infection can be a sight threatening condition but is not usually serious if treated promptly. See your doctor immediately if you have symptoms. You may need to use eye ointment or drops to clear up the infection (see Herpes simplex eye infections - treatment).
In some cases, a herpes simplex eye infection can permanently damage your eyesight if you do not get it treated straight away.
Some people with a herpes simplex eye infection do not have noticeable symptoms.
Otherwise, symptoms include:
- eye redness
- moderate to severe pain in or around your eye
- sensitivity to light (photophobia)
- a watery eye
- vision problems (for example, blurred vision)
You may also feel generally unwell or have a fever (a temperature above 38ºC or 100.4ºF).
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 mouth or face. The virus is extremely infectious. If you have a cold sore avoid touching it. If you have touched the sore do not touch your eyes or genitals until you have first washed your hands thoroughly.
The virus is usually contracted during childhood, for instance by being kissed by someone with a cold sore, and can remain dormant for many years until activated by a trigger.
A herpes simplex eye infection can also be caused by the herpes simplex virus type 2 (HSV-2). HSV-2 is the usual cause of genital herpes.
Triggers of a herpes simplex eye infection
The virus can be reactivated spontaneously or by certain factors, which then lead to symptoms.
These trigger factors include:
- another illness or an injury
- exposure to strong sunlight
- a fever (high temperature above 38°C)
- exposure to cold winds
- (in women) having your period
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.
It is important to see your doctor if you have symptoms of a herpes simplex eye infection. An untreated infection can permanently damage your eyes.
Your doctor will ask about your symptoms and examine your eyes to rule out any other conditions.
They may put a harmless dye into your eye to see any irregular areas or injury. This is called fluorescein staining.
Your doctor may also test your vision using a Snellen chart (a chart with blocks of letters that gradually get smaller).
Your eye specialist
If your doctor thinks you may have a herpes simplex eye infection, they will send you to an eye specialist (ophthalmologist) who should see you as quickly as possible.
This is because herpes simplex infection is difficult to diagnose without specialist knowledge and equipment. It can also permanently affect your eyesight if not treated quickly.
In addition to the tests above, your eye specialist may take a sample of the fluid (tears) from your eye for laboratory testing.
Treatment of a herpes simplex eye infection depends on how bad the infection is and what part of the eye is affected. It is important to follow the advice you are given and take any prescribed treatment carefully and for the complete course, to help avoid developing complications.
Sometimes, your eye specialist may advise no treatment. If this is the case, you may be asked to attend regular check ups to make sure 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 (steroid medication, which reduces inflammation)
Sometimes, your eye specialist may advise you to take antiviral and steroid eye drops or ointment at the same time. This is because some research suggests that this can clear up the infection more quickly.
Before you start treatment with eye drops or ointment, your eye specialist may 'clean' your eye by gently scraping infected cells from its surface. This is also known as 'debridement'.
This is carried out under local anaesthetic (the eye is numbed) so you do not feel any pain while it is being done.
Tablets are not normally used for treating a herpes simplex eye infection.
However, antiviral tablets may be prescribed after treatment to stop the infection returning. You may have to keep taking them for up to a year after the infection has gone.
Wearing contact lenses
It is best not to wear contact lenses until you have finished treatment and the symptoms have gone completely.
A herpes simplex eye infection is not usually serious. But in some cases, it can permanently affect your eyesight if you do not treat it quickly.
If you have symptoms, speak to your doctor as soon as possible.
Complications of herpes simplex eye infections include:
- an ulcer on your cornea (the front of your eye)
- scarring of your cornea, which can cause vision problems and may require a cornea transplant (an operation to replace the cornea in your eye)
- further infections caused, for example, by bacteria or fungi
- glaucoma (an eye condition that can affect your vision)
- acute retinal necrosis (ARN), extremely rare development which can cause loss of vision in patients with severely compromised immune systems, such as those with HIV
If you develop problems with your vision, this may affect your driving.