Herpes Simplex Eye Infections

Overview

A herpes simplex eye infection happens when the herpes simplex virus — the same common virus that causes cold sores around the mouth — gets into the eye. It most often affects the cornea, the clear see-through window at the front of the eye. The virus usually stays quiet in the nerves of the face and only causes trouble when it wakes up again. When it does, it can make the eye red, sore and sensitive to light. It is not a sexually transmitted infection in this situation, and it is not the same as the cold sore virus being spread by touch to other people's eyes in most cases. Most people who get it recover well with prompt treatment, but it can come back.

It is fairly common. Herpes simplex is one of the more frequent causes of a red, painful eye seen in general practice and eye clinics. Many people carry the virus without ever having eye trouble, and only a small share of them ever get an eye infection.

It can affect anyone at any age. First infections are often seen in children and young adults, usually alongside or after cold sores. Repeat flare-ups are more common in adults, and the risk of more serious disease rises in older adults, in people whose immune system is weakened by illness or medication, and in anyone who has had it before. People who use steroid eye drops without antiviral cover, or who have had an eye injury, are also at higher risk.

Symptoms

Common symptoms

• A red eye, often just in one eye
• Pain or a gritty, scratchy feeling in the eye
• Watery eye or discharge
• Sensitivity to light (this is called photophobia — light feels uncomfortable or painful)
• Blurred or misty vision
• A feeling that something is in the eye
• A blister or crop of small sores on the eyelid, or a cold sore nearby
• Sometimes a branching, tree-like pattern on the surface of the eye that a doctor can see with a special light

Symptoms in children

• Being reluctant to open the eye, or rubbing it a lot
• A red, watery eye with lots of blinking
• Sores or crusting on the eyelid or around the mouth at the same time
• Being irritable, off food, or having a mild temperature with the eye symptoms
• Children may not say their vision is blurry — they may just seem clumsy or hold things closer

Symptoms in older adults

• Symptoms may be milder than the eye looks, because the surface of the eye can be less sensitive with age
• Blurred vision or a general sense that sight is not as good as usual
• More frequent flare-ups, especially if the immune system is weaker
• A higher chance of scarring on the clear front of the eye after repeated episodes
• Dry eye and irritation that can make the infection harder to spot

Causes

Main causes

• Infection with herpes simplex virus type 1, the virus that causes cold sores. Type 2, usually linked to genital herpes, can occasionally affect the eye too.
• Reactivation of virus that has been sleeping in the nerve that supplies the face (the trigeminal nerve), often years after the first infection
• Spread from a cold sore on the lip or face to the eye, for example by touching a sore and then rubbing the eye
• In some people, the eye problem is partly caused by the body's immune reaction to virus particles left in the eye, rather than by active virus alone

Risk factors

• Having had a herpes simplex eye infection before — this is the biggest risk factor
• A weakened immune system, from illness, some medicines, or treatments such as chemotherapy
• Physical or emotional stress, fever, and other infections
• Strong sunlight or sunburn on the face
• Eye injury or recent eye surgery
• Using steroid eye drops without antiviral cover
• Frequent cold sores, or close contact with someone who has an active cold sore

When to see a doctor

See a doctor urgently if:

• A red, painful eye with light sensitivity, especially if it came on over a day or two
• Sudden change in vision, or a grey or cloudy patch in your sight
• A blister or cold sore near the eye
• Any red eye in a contact lens wearer
• Eye symptoms along with feeling unwell, or a weakened immune system

Book a routine appointment if:

• Mild eye irritation that keeps coming back in the same eye
• A previous herpes simplex eye infection and you want advice on spotting early signs
• Ongoing dry eye or discomfort after a treated infection
• Questions about contact lenses, sport or work after an eye infection

Diagnosis

A doctor or eye specialist will ask about your symptoms, your past cold sores and any previous eye infections, then examine your eye closely. They usually use a slit lamp — a special microscope with a bright light — and put a harmless yellow dye in the eye. The dye shows up any damage or pattern on the surface of the eye, and the branching pattern often seen in herpes simplex infection is quite distinctive.

Tests that may be done

• A vision check to see how clear your sight is
• Slit lamp examination with special dye to look at the surface of the eye
• A soft swab or tiny scrape from the eye or eyelid sore, sent to the lab to look for the virus's genetic material (a PCR test)
• Checking for other causes, such as a scratch, dry eye or a contact lens problem
• Blood tests are not usually helpful for the eye infection itself and are rarely needed

What to expect at your appointment

The examination is quick and not painful, although the bright light can feel uncomfortable when your eye is sore. The dye may make your vision slightly blurry and yellow for a short while. You may be seen by your GP and then referred to an eye clinic, or sent straight to an eye service if the doctor is concerned. Most people get a clear answer and start treatment the same day.

Treatment

Treatment aims to calm the infection, protect the surface of the eye, ease pain and lower the chance of scarring and repeat flare-ups. Antiviral treatment started early works best. Which form you get — drops, ointment or tablets — depends on how deep the infection is and what the eye specialist finds.

Self-care at home

• Rest your eyes and take breaks from screens if they feel strained
• Do not rub the eye, and wash your hands often, especially after touching your face
• Use a clean towel and flannel and do not share them with anyone else while the infection is active
• Leave contact lenses out until a doctor says it is safe to wear them again, and clean or replace lenses and cases as advised
• Sunglasses can help if light feels uncomfortable
• Simple pain relief you would normally take for a headache can ease discomfort — ask your pharmacist if you are unsure what is suitable for you
• Keep to any follow-up appointments, even if the eye feels better, because the surface of the eye can take a while to fully heal
• Avoid touching or squeezing cold sores near the eye

Medical treatments

Doctors treat herpes simplex eye infections with antiviral medicines. These come as eye drops, eye ointment or tablets, and they work by stopping the virus from multiplying. Which form is used depends on how the eye is affected — surface infections may be treated with drops or ointment, while deeper or more stubborn infections often need tablets. Sometimes the eye specialist gently removes loose, damaged surface cells to help healing. Steroid eye drops are used with great care: on their own they can make a herpes infection worse, so they are only used in particular situations and only alongside antiviral treatment. You should never start steroid drops on your own or use someone else's drops. Your doctor will also check for other problems, such as a dry eye, that need treating.

When is surgery considered?

Surgery is not used to treat the infection itself. However, if repeated infections leave a scar on the clear front of the eye that badly blurs vision, a corneal transplant operation may be considered later on. This replaces the damaged clear window with healthy donated tissue. It is only offered after careful discussion with an eye specialist, and many people never need it.

Living with this condition

Most people carry on with normal life during and after an episode, with a few adjustments. Expect some blurriness and light sensitivity for a while, and plan for rest breaks. Because the infection can return, it helps to learn your own early warning signs — a familiar gritty feeling, redness in the same eye, or extra sensitivity to light — and to get seen quickly when they appear. Keep a note of when flare-ups happen and what seemed to set them off; this is useful information for your doctor.

Lifestyle tips

• Try to keep stress in check and protect your sleep, since flare-ups often follow tiring or stressful periods
• Wear sunglasses or a hat with a brim in bright sun, and use sun protection on your face
• Wash your hands regularly and avoid touching cold sores and then your eyes
• Do not share towels, flannels, eye make-up or contact lens equipment
• Replace eye make-up after an infection and avoid it while the eye is inflamed
• Follow your eye care team's advice about contact lens wear
• If you get cold sores, treat them early and keep them away from your eyes

Diet and exercise

There is no special diet that treats or prevents herpes simplex eye infections. Eating a balanced diet, drinking enough water and staying active in the ways you enjoy all help your general health and your immune system. If bright light or sweat bothers your eye during a flare-up, choose indoor or shaded activity until it settles. Ask your doctor if you are unsure about exercise after treatment.

Mental health and emotional wellbeing

An eye problem that comes back can be genuinely unsettling. Many people worry about their sight, about missing work or school, or about when the next flare-up will happen. That worry is understandable and very common. Talking to your doctor about your fears, writing down questions before appointments, and telling family or friends what you need can all help. If low mood, anxiety or worry about your eyes is affecting your sleep, work or daily life, please speak to a healthcare professional. If you ever feel you cannot cope or have thoughts of harming yourself, contact your local emergency number or a crisis support service in your country straight away — you deserve help and you do not have to manage alone.

Prevention

You cannot completely prevent herpes simplex eye infections, because the virus can stay in the body and wake up on its own. But you can lower the chances of a flare-up and of passing the virus to your eye. Wash your hands often, avoid touching cold sores and then your eyes, do not share towels, flannels or eye make-up, and protect your face from strong sun. If you get frequent flare-ups, your eye specialist may discuss a longer course of preventive antiviral treatment. Never use steroid eye drops unless a doctor has prescribed them for you.

Vaccines

There is currently no vaccine available to prevent herpes simplex eye infections.

Screening programmes

There is no routine screening test for herpes simplex eye infections. Instead, people who have had an episode are usually advised to return promptly if symptoms come back, so treatment can start early.

Complications

If left untreated

• The infection can spread deeper into the cornea and cause an ulcer (an open sore on the surface of the eye)
• Scarring of the clear front of the eye, which can leave lasting blurred vision
• Long-term or repeated inflammation that damages the surface of the eye
• A higher risk of a secondary bacterial infection
• Rarely, serious damage to the eye that threatens sight
• More frequent flare-ups over the years if episodes are not treated

Long-term outlook

The outlook is good for most people. With early antiviral treatment, the infection usually settles within a couple of weeks and vision often returns to normal. Some people do get repeat episodes, and a small number develop scarring that affects sight — but regular follow-up, knowing your warning signs and getting seen quickly make a real difference. If you notice changes in your vision between appointments, tell your eye care team rather than waiting.

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