Corneal ulcer: symptoms, causes, treatment and when to get urgent help

The cornea is the clear window at the front of the eye. University Hospitals Plymouth NHS Trust describes a corneal ulcer as a non-penetrating erosion or open sore in its outer layer, which happens when the surface is damaged or compromised in some way. Ulcers may be sterile (no infection) or infectious.

Moorfields Eye Hospital uses the term microbial keratitis for an infection on the cornea, often related to contact lens wear or, less commonly, due to a scratch on the surface of the eye or a pre-existing eye condition.

Moorfields says microbial keratitis causes a painful red eye and sometimes blurred vision. At first it feels as though there is something in your eye, and the eye becomes increasingly painful as the ulcer develops on the surface of the cornea. Sometimes you can see the ulcer, which looks like a small white spot on the cornea over the coloured part of the eye.

The Plymouth leaflet lists the signs and symptoms as a red eye, moderate to severe pain (not in all cases), watering, light sensitivity, discharge, a pricking sensation, and a white spot on the cornea depending on severity.

Moorfields says that if your eyesight becomes more blurred, if your eye becomes more red or painful rather than improving, or if you can see a white spot getting bigger on the cornea, you should telephone for advice or attend your local A&E department. The same applies to a red, painful eye with light sensitivity or reduced vision that has not been assessed: do not wait to see if it settles.

Plymouth says prompt early attention by an ophthalmologist (eye doctor) helps prevent complications. If you wear contact lenses and develop a red, painful eye, Moorfields asks you not to wear lenses while the infection is present and for a few weeks after it clears.

Plymouth says there are many causes of corneal ulcers, but soft contact lens wearers have an increased risk if they do not stick to a strict routine for hygiene and wear. It lists severe dry eyes, blepharitis, corneal injuries and abrasions, inflammatory diseases, and viral infections such as herpes simplex (cold sores) as increasing risk.

Moorfields says microbial keratitis is more likely with incorrect contact lens cleaning or storage, incorrect use of disposable lenses, or wearing lenses overnight.

Plymouth says corneal ulcers are diagnosed with a careful examination using a slit lamp microscope. Special eye drops containing a dye called fluorescein may be put in the eye to show the ulcer. If infection is suspected, the doctor may take swabs and send them to the laboratory, after anaesthetic eye drops numb the surface of the eye, and cells may be gently scraped from the corneal surface and tested to show the type of infection.

Moorfields adds that results can sometimes take several days to come back, depending on the bacteria being tested for.

Plymouth says treatment depends on the cause and prompt treatment is essential to prevent further injury to the cornea. Bacterial or fungal ulcers require aggressive treatment; in some cases antibacterial eye drops are used every 15 minutes. Antiviral or antifungal drops are prescribed as soon as the infection is identified. Non-infectious (sterile) ulcers are treated by reducing inflammation with anti-inflammatory drops, frequent lubrication and antibiotics.

Moorfields says antibiotic drops are usually used and you are likely to need to put them in very frequently at first, up to every hour and sometimes through the night if the infection is severe. The frequency is then reduced once the ulcer is seen to be getting smaller. Antibiotics may be changed if there is no improvement after several days or if sample results show another drop would be more appropriate. It stresses that you should put drops in regularly, as these infections can get much worse if not treated properly.

You may be asked to return in a few days to see if the infection is improving; if the infection is mild you may only be asked to return if symptoms worsen.

Plymouth says ulcers usually respond to treatment with a good visual outcome in most cases. Untreated, a corneal ulcer or infection can permanently damage the cornea. It lists complications of corneal scarring and severe vision loss, and an uncommon complication is perforation of the eye, in which infection spreads inside the eye and increases the risk of permanent visual impairment.

Moorfields says microbial keratitis can sometimes affect your vision and may leave a scar, even with correct treatment. After the infection has fully recovered, it asks you to return to your contact lens practitioner to check lens fit and use.

Plymouth advises washing hands, paying rigorous attention to lid hygiene and cleanliness when handling contact lenses, and avoiding wearing lenses at night and for prolonged periods. Moorfields advises not wearing contact lenses while an infection is present and for a few weeks after it clears.

If you have dry eyes, blepharitis or a past eye injury, ask your optometrist or eye doctor about how to protect the surface of your eye.

A suspected corneal ulcer is usually seen the same day by an eye casualty, hospital eye service or emergency department, often after an optometrist, GP or NHS 111 has advised. Some people have private ophthalmic care. The key point is speed: because the treatment is frequent eye drops and close follow-up, early assessment matters more than where it takes place.