Corneal Ulcer

What a corneal ulcer is

The cornea is the transparent front window of the eye. It focuses light and is covered by a thin protective skin (epithelium). When that surface breaks down and germs or inflammation eat into the deeper layers, an ulcer forms. Doctors also call it ulcerative keratitis, because it is a form of keratitis (inflammation of the cornea) with tissue loss.

A simple scratch, or corneal abrasion, affects only the surface and heals in a day or two. An ulcer goes deeper, has a white or gray patch of infection or inflammation, and can scar or even perforate the cornea.

Symptoms

• eye pain, often severe, and a feeling that something is stuck in the eye
• a very red eye
• sensitivity to light
• blurred or reduced vision
• tearing, or a yellow or white discharge
• a white, gray or cream spot on the cornea, sometimes visible in a mirror
• swollen eyelids

Pain is usually out of proportion to how the eye looks. Fungal and amoebic ulcers can develop more slowly, over days to weeks, and are sometimes mistaken for conjunctivitis. Herpes ulcers can be less painful because the virus dulls corneal sensation.

Causes

Bacterial ulcers

The most common type. Pseudomonas is the classic culprit in contact lens wearers and can destroy the cornea within 24 to 48 hours. Staphylococcus and Streptococcus are common after injury or in eyes with surface disease. See bacterial keratitis.

Fungal ulcers

These follow injury with plant material, such as a twig or thorn, and are more common in warm, humid climates and in farm workers. They can also occur in people using steroid eye drops. They have feathery edges and respond slowly to treatment.

Acanthamoeba

A tiny amoeba found in tap water, pools, hot tubs and soil. It causes acanthamoeba keratitis, almost always in contact lens wearers who rinse lenses or cases with tap water or swim in lenses. Pain is often extreme.

Herpes simplex virus

The cold sore virus can infect the cornea, producing branching (dendritic) ulcers that tend to recur. Herpes simplex keratitis is a leading infectious cause of corneal blindness in developed countries.

Non-infectious ulcers

• severe dry eye
• an eye that does not close properly, for example after Bell's palsy or a thyroid eye problem
• loss of corneal sensation (neurotrophic ulcers), after shingles, diabetes or nerve surgery
• autoimmune diseases such as rheumatoid arthritis
• vitamin A deficiency, a major cause in low-income countries

Contact lenses and corneal ulcers

Contact lens wear is the single biggest risk factor in high-income countries. Risk rises sharply with:

• sleeping in lenses, including "extended wear" lenses
• swimming or showering in lenses
• rinsing lenses or cases with tap water
• topping up old solution instead of replacing it
• wearing lenses longer than their replacement schedule

If a lens-wearing eye becomes painful and red, take the lens out, do not put it back in, and bring the lens and case to the eye doctor so they can be cultured.

How it is diagnosed

An optometrist or ophthalmologist examines the eye with a slit lamp, a microscope with a bright light. Orange fluorescein dye shows the area of missing surface as bright green under blue light. The doctor measures the ulcer's size and depth and checks for inflammatory cells in the front chamber of the eye.

For larger, central or unusual ulcers, the doctor gently scrapes the ulcer under numbing drops and sends the sample for staining and culture. This identifies the germ and guides treatment. Confocal microscopy can help find fungi and acanthamoeba.

Treatment

• Bacterial: antibiotic drops, often every hour day and night for the first 24 to 48 hours, then tapered. Strong "fortified" drops are used for large or severe ulcers.
• Fungal: antifungal drops such as natamycin for weeks to months, sometimes with tablets.
• Acanthamoeba: special anti-amoebic drops for many months.
• Herpes: antiviral drops, gel or tablets.
• Pain and inflammation: dilating drops relax the focusing muscle and ease pain. Steroid drops are added only by an eye doctor, after infection is under control, because steroids can worsen fungal and herpes infections.
• No eye patch for contact lens-related ulcers, because patching can encourage bacterial growth.

Severe or non-healing ulcers may need a corneal glue, an amniotic membrane graft, or a corneal transplant. Do not use leftover eye drops, especially steroid drops, on a red, painful eye without being examined.

Complications and healing time

Small bacterial ulcers often heal within 1 to 3 weeks with treatment. Fungal and acanthamoeba ulcers can take months. Possible complications include:

• corneal scarring and permanent blurred vision
• an irregular cornea needing a rigid contact lens or surgery
• thinning and perforation of the cornea
• spread of infection inside the eye (endophthalmitis) and loss of the eye

Outcome depends mainly on how quickly treatment starts and whether the ulcer is in the center of vision.

Preventing corneal ulcers

• Never sleep, swim or shower in contact lenses unless your eye doctor specifically approves it.
• Clean and store lenses only in fresh disinfecting solution, and replace the case every 3 months.
• Wear protective glasses for gardening, yard work and power tools.
• Use lubricating drops or ointment if your eye does not close fully or is very dry.
• Seek care early for any eye injury that becomes more painful over the next day.

Frequently asked questions

What does a corneal ulcer look like?

It often looks like a white, gray or cream spot or patch on the clear front of the eye, over the colored iris. The white of the eye is usually very red, and there may be discharge. Small ulcers can be invisible without a slit lamp and fluorescein dye.

How long does a corneal ulcer take to heal?

With prompt treatment, a small bacterial ulcer usually heals in 1 to 3 weeks. Large, deep, fungal or acanthamoeba ulcers can take several months. Healing is checked at frequent follow-up visits, and some people are left with a scar that affects vision.

Can a corneal ulcer heal on its own?

No infectious corneal ulcer should be left to heal on its own. Bacterial ulcers can perforate the cornea within days. Treatment with the right drops, started as early as possible, gives the best chance of healing without scarring or vision loss.

Can a corneal ulcer cause blindness?

Yes. Corneal ulcers are a leading cause of preventable vision loss worldwide. Scarring in the center of the cornea, perforation or spread of infection inside the eye can cause permanent loss of sight. Fast treatment greatly reduces this risk.

Can I wear contact lenses after a corneal ulcer?

Usually yes, once your eye doctor confirms the ulcer has fully healed and the eye is quiet. Expect to start with a new lens and case, and review your lens habits. Daily disposable lenses are often recommended, and never sleeping in lenses.