Herpes Simplex Virus Keratitis

Herpes simplex virus keratitis is a viral infection of the cornea (the clear surface, or ‘window’ of the eye). It is usually caused by the herpes simplex virus (HSV-1), the same virus that causes cold sores. HSV keratitis generally affects one eye but on rare occasions both eyes.


Symptoms may include:

  • A red eye
  • Eye pain or foreign body sensation
  • Sensitivity to light
  • Blurred vision
  • Small blisters around the eyelid


Why have I got it?

HSV-1 is a very common virus, passed on by direct skin-to-skin contact. Most people are infected by the time they are 60 but only one in three will notice any symptoms. After the first infection, the virus remains in the nerves of the face and can re-emerge at any time. It can cause a cold sore, or an ulcer in the eye. The virus can be spread directly to the eye from a cold sore, so avoid touching your eyes if you have a cold sore present.

Symptoms can be worse if you have eczema or a reduced ability to fight infections, taking medications that affect immunity, for example.


How is it diagnosed?

A clinician will examine the eye. A sample may be taken from the corneal surface to confirm the presence of HSV-1.

This is performed with a cotton bud, after numbing the eye so will not be painful. A negative result does not mean you do not have HSV-1, as testing may not be positive in 100% of cases.


What is the treatment?

  • Antiviral eye gel – a course of eye gel (ganciclovir) is the treatment for most cases.
  • Antiviral tablets – a 7-day course of antiviral tablets (e.g. aciclovir, valaciclovir) may be required in severe and/or recurrent cases.
  • Steroid eye drops – sometimes these are used to reduce inflammation and minimise scarring.
  • Advice for contact lens wearers - contact lenses should not be worn until all symptoms have gone.


Will it come back?

If you have HSV keratitis, it can become a recurrent problem. Similar to cold sores, the virus can re-emerge at any time. Around half the people who get HSV keratitis will get it again within five years. If you keep getting recurrent infections, your eye doctor might recommend that you take daily antiviral tablets to help prevent infections.


Will it damage my eyesight?

Severe or repeated episodes can result in scarring of the cornea, which can cause blurred vision. Infection can also damage the nerves of the cornea, leading to a lack of sensation.Each time you have an episode you should see an eye doctor as soon as possible so they can check your eye and give you the correct medication.


When to seek advice

If you develop blisters around the eye, a red or painful eye, light sensitivity, blurred vision, or new floaters you should contact Moorfields for advice or visit your GP / local A&E department.



Administering Eye Drops

video transcript

Before putting in your eyedrops, first check that the drops are still in date.

If you were using a new bottle of eyedrops also check that the seal is not broken make sure you're putting the correct drops into the correct eye.

Let the correct time to instill your drops. Place a clean tissue on a flat surface wash your hands thoroughly with soap and water invert the bottle two or three times to ensure the contents are evenly mixed together.

Remove the lid and place it on the tissue tilt your head back, pull down your lower lid and form a small pocket. Make sure that the tip of the bottle does not come into contact with your skin or eyelashes as it might contaminate the drops.

Look up and gently squeeze the bottle so that a single drop falls into the pocket made by your lower lid.

Blink the drops in press lightly on the inner corner of your eye this enables more of the drop to be absorbed and not run away down your tear duct.

Wipe any excess fluid from your closed eyelids with a clean tissue.

Recap your drop bottle if you have more than one drop to instill. Wait at least 5 minutes before putting in another drop.

Wash your hands with soap and water to remove any traces of medication.

If you have any problems please contact our nurse led helpline service Moorfields Direct on 0207 566 2345