Herpetic anterior uveitis: eye inflammation linked to herpes viruses

The uvea is the middle layer of the eye. Moorfields Eye Hospital describes uveitis as inflammation of this layer, made up of the iris (the coloured part), the ciliary body and the choroid. Anterior uveitis affects the front of the eye, usually the iris, and is the most common type of uveitis.

Herpetic anterior uveitis is the form where a herpes virus is thought to be responsible for the inflammation. The two relevant viruses are herpes simplex, which also causes cold sores, and varicella zoster, which causes chickenpox and later shingles. The NHS lists both among the infections that can cause uveitis.

Anterior uveitis usually affects one eye. The NHS lists eye pain that may feel worse when reading, red or watery eyes, reduced or blurred vision, sensitivity to light, and flashes, floaters or dark spots. RNIB adds that acute anterior uveitis typically starts suddenly, with symptoms developing over hours to days.

For a herpes simplex eye infection specifically, the NHS lists eye pain, a red eye, watering, sensitivity to light, blurred vision or other changes to eyesight, a swollen eyelid, and blisters or a rash on the eyelid or the skin around the eye. It says a herpes simplex eye infection is more likely if you have had one before or have had cold sores.

With shingles, the NHS says the rash may be in and around the eye, making it sore and red. Eye problems can be a complication of shingles and can lead to sight loss, which is why treatment as early as possible is advised.

The NHS advice for a suspected herpes simplex eye infection is to ask for an urgent GP appointment or get help from NHS 111 if you have eye pain, a red eye that is getting worse, any change to your eyesight such as blurring, or a swollen irritated eyelid that has not improved. 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.

For shingles, the NHS says to seek urgent advice if the rash is on your eye or nose or you have changes to your vision. The Scottish community eyecare guidance, written for optometrists, notes that eye lesions may occur early or develop up to a month after the skin rash begins, so monitoring may continue even after the rash starts to improve.

Once you have had the herpes simplex virus it stays in the body and usually causes no symptoms, but sometimes it causes an eye infection. The NHS says this is more likely if you have a weakened immune system, and that infection may be triggered by an illness, stress, exposure to bright light or an eye injury. You usually acquire the virus through skin-to-skin contact with someone who has a cold sore.

The College of Optometrists describes herpes zoster ophthalmicus as a potentially sight-threatening viral infection of the trigeminal nerve caused by reactivation of the varicella zoster virus, with eye involvement that can include conjunctivitis, keratitis and uveitis on the same side as a rash on the forehead and scalp. It says two-thirds of cases occur in people over 50.

The NHS says that if a GP thinks you have uveitis or a herpes simplex eye infection they will refer you to an eye specialist (ophthalmologist). If it is not clear what is causing a red eye, you may be referred for tests. The NHS notes that conditions with similar symptoms include glaucoma, other infections or inflammation such as conjunctivitis, keratitis or scleritis, and an eye injury, which is one reason a specialist assessment is needed.

The Dudley Group leaflet on uveitis explains that doctors may take a detailed history of other body systems and, depending on the clues and severity, arrange blood tests, scans or other investigations, particularly for recurrent episodes or when both eyes are involved.

For a herpes simplex eye infection the NHS says you will usually be prescribed an antiviral medicine such as aciclovir, as eye ointment, eye drops or sometimes tablets, or an antiviral with steroid eye drops to reduce swelling. Most infections get better in a couple of weeks and will not permanently affect eyesight. If you wear contact lenses, the NHS says not to wear them until 24 hours after all symptoms have gone.

For shingles affecting the eye, the Scottish eyecare guidance, citing College of Optometrists advice, says early treatment with oral antivirals, optimally within 72 hours of the rash starting, reduces the likelihood of eye disorders and lessens acute pain. Suspected cases should be referred urgently, same day, for systemic antiviral treatment. Secondary care may add topical steroids, other antivirals or treatment for complications.

RNIB explains that steroid eye drops are used to reduce inflammation in anterior uveitis and may be prescribed as often as every hour at first, then reduced slowly by the ophthalmologist. It stresses not to stop them until the ophthalmologist says it is safe, even if symptoms disappear, because stopping too soon can allow inflammation to return. Drops that relax the iris muscles can ease pain. When infection is the cause, treatment also focuses on the underlying infection with antiviral medicines.

Most herpes simplex eye infections settle with treatment, but the NHS says they commonly come back. If treatment does not work or infections keep occurring, the cornea can become scarred, causing sight loss, and a cornea transplant may be needed. A doctor may recommend taking antiviral tablets every day to help prevent repeat infections.

For shingles of the eye, the Scottish guidance says herpes zoster ophthalmicus can result in moderate to severe loss of vision in a significant proportion of people with eye involvement, even with timely treatment, and is associated with chronic and recurrent complications. Ongoing follow-up is therefore important.

In the NHS, suspected herpes eye infection is handled through urgent GP, optometrist or hospital eye casualty routes, and same-day assessment is the aim. Private eye clinics can see people quickly too, but the tests and medicines involved are the same. Because this condition can recur, ask whichever service you use who will monitor the eye over time and who to contact if symptoms return.