Herpes simplex keratitis (eye herpes): symptoms, treatment and recurrence

The cornea is the clear, dome-shaped window at the front of the eye. In herpes simplex keratitis the herpes simplex virus infects this surface and the layers just beneath it, causing inflammation and sometimes an ulcer. The NHS also calls it a herpes simplex eye infection, eye herpes or ocular herpes.

Moorfields explains why it can recur. HSV-1 is a very common virus passed on by direct skin-to-skin contact. Most people are infected by the age of 60, although 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, producing a cold sore on the lip or, less often, an ulcer in the eye.

The NHS adds that it is unlikely that you will pass the virus on to someone else from an eye infection, but advises avoiding touching the eye and washing the hands regularly.

The NHS notes that the symptoms can be similar to other eye conditions. It is more likely to be a herpes simplex eye infection if you have had one before or have had cold sores.

• Eye pain or a feeling of something in the eye (Moorfields describes a foreign body sensation).

• A red eye and watering.

• Sensitivity to light.

• Blurred vision or other changes to eyesight.

• A swollen eyelid.

• Blisters or a rash on the eyelid or the skin around the eye.

The NHS says it is important to get medical help for symptoms of a herpes simplex eye infection because it can sometimes affect your sight. It advises asking for an urgent GP appointment or getting help from NHS 111 if you have eye pain, a red eye that is getting worse, any changes to your eyesight such as blurred vision, or a swollen, irritated eyelid that has not got better.

It says to call 999 or go to A&E if you have a red eye and it hurts to look at light, your eye is very dark red, or one pupil is bigger than the other. Moorfields adds that every time you have an episode you should see an eye doctor as soon as possible so that your eye can be checked and the correct medicine given.

Contact lens wearers should stop wearing lenses. The NHS says not to wear them until 24 hours after all symptoms have gone, and Moorfields advises that lenses should not be worn until all symptoms have gone.

A clinician examines the eye, usually with a microscope that magnifies the front of the eye. The classic herpetic ulcer has a branching shape; the NHS Scotland community eyecare guideline for viral keratitis refers to dendritic ulcers and recommends a low threshold for referral because the condition is potentially blinding.

Moorfields says a sample may be taken from the corneal surface with a cotton bud after the eye has been numbed, so it is not painful, to confirm the virus. A negative result does not mean you do not have HSV-1, because testing is not positive in every case. In many cases the diagnosis is made from the appearance of the eye and the history.

The NHS says that if a GP thinks you have a herpes simplex eye infection they will refer you to an eye specialist, usually to be seen the same day so that treatment can start quickly. Some opticians can also treat certain eye conditions under NHS arrangements; the NHS suggests checking first before making an appointment.

The NHS says you will usually be prescribed an antiviral medicine such as aciclovir, taken as eye ointment, eye drops or sometimes tablets, or an antiviral medicine along with steroid eye drops to reduce swelling. Most infections get better with treatment in a couple of weeks and do not permanently affect eyesight.

Moorfields states that an antiviral eye gel (ganciclovir) is the treatment for most cases, that a 7-day course of antiviral tablets such as aciclovir or valaciclovir may be required in severe or recurrent cases, and that steroid drops are sometimes used to reduce inflammation and minimise scarring.

The NHS says it is common for herpes simplex eye infections to come back. Moorfields says that around half of the people who get HSV keratitis will have another episode within five years, and that if you keep getting recurrent infections your eye doctor might recommend daily antiviral tablets to help prevent them. NHS Scotland’s guideline adds that low-dose oral antivirals used preventively reduce the recurrence of stromal disease by 50 per cent.

Repeated episodes matter because of what they do to the cornea. Moorfields says severe or repeated episodes can result in scarring that can cause blurred vision, and infection can also damage the corneal nerves, leading to a lack of sensation. The NHS notes that if infections keep occurring they may become less painful, which is another reason to be checked rather than assume that a milder episode is harmless.

Triggers named by the NHS include illness, stress, exposure to bright light and an eye injury, and the infection is more likely if the immune system is weak. Moorfields adds eczema and medicines that affect immunity to the list of things that can make symptoms worse.

In the NHS, eye herpes is usually assessed through a GP, community optometrist or eye casualty and managed by a hospital eye service. Some community optometrists in Scotland treat uncomplicated cases under a national scheme, with referral to ophthalmology if healing is delayed or the deeper layers of the cornea are involved.

Private ophthalmologists can assess and treat the condition in the same way, and some people choose them for speed or continuity. Whichever route you use, tell the clinician about previous episodes, any contact lens use and medicines that affect immunity, since these change the plan.