A herpes simplex eye infection is a viral infection that can cause a painful, red eye. It's also called eye herpes or ocular herpes. It's important to get treatment because it can sometimes affect your sight.

Herpes simplex eye infections usually affect only one eye.

The symptoms can be similar to some other eye conditions, and can include:

• eye pain
• a red eye
• watering of your eye
• sensitivity to light
• blurred vision or other changes to your eyesight
• a swollen eyelid
• blisters or a rash on your eyelid or the skin around your eye

It's more likely to be a herpes simplex eye infection if you've had one before, or if you've had cold sores.

If you keep getting herpes simplex eye infections they may become less painful.

Find out about other conditions that can cause:

• a red eye
• eyelid problems
• watering eyes

See a GP or go to an opticians if:

Ask for an urgent GP appointment or get help from NHS 111 if:

Call 999 or go to A&E if:

If a GP thinks you have a herpes simplex eye infection they'll refer you to an eye specialist (ophthalmologist). You'll usually be seen the same day so that you can start treatment quickly.

You'll usually be prescribed either:

• an antiviral medicine such as aciclovir, taken as eye ointment, eye drops or sometimes tablets
• antiviral medicine with steroid eye drops to reduce swelling

Most infections will get better with treatment in a couple of weeks and will not permanently affect your eyesight.

It's common for herpes simplex eye infections to come back. If you keep getting them a doctor might recommend that you take antiviral tablets every day to help prevent infections.

If treatment does not work or you keep getting the infections, your cornea (the transparent front part of your eye) might become scarred, causing sight loss. If this happens you might need to have a cornea transplant.

If you use contact lenses, do not wear them until 24 hours after all your symptoms have gone.

Most herpes simplex eye infections are caused by the same herpes simplex virus that causes cold sores.

You usually get the herpes simplex virus from skin to skin contact from someone with a cold sore. Once you have it, it stays in your body. It does not usually cause any symptoms, but sometimes it can cause eye infections.

This is more likely if you have a weakened immune system. It might also be triggered by an illness, stress, exposure to bright light or an eye injury.

You're unlikely to pass the virus on to someone else from an eye infection, but try to avoid touching your eye, and wash your hands regularly.