Contact Lens Keratitis – the Complication You Must Not Wait On

Of all the complications of contact lenses, infectious keratitis is the one that worries cornea specialists most. It is not common – most lens wearers will never encounter it – but when it occurs it can progress within hours and leave a permanent scar right in the centre of vision. This page explains who is at risk, how to recognise it early, what happens at the examination and during treatment, and the rules that prevent most cases.

What keratitis is and why contact lenses are involved

The cornea is the clear window at the front of the eye. Normally its outer epithelial layer, the tears and blinking form a very effective barrier against infection. A contact lens weakens this barrier in several ways: it reduces the oxygen reaching the cornea, creates microscopic scratches in the epithelium, and traps a layer of fluid between itself and the eye in which bacteria can multiply. When the lens, the case or the solution is contaminated, an infection has the opportunity to invade the corneal tissue itself.

Who is at risk

The risk factors are well known, and most are within the wearer’s control:

• Sleeping in lenses. This is the strongest risk factor, even with lenses approved for overnight wear.
• Contact with water. Rinsing lenses or the case in tap water, showering, or swimming in a pool, the sea or a hot tub with lenses in.
• Case and solution hygiene. “Topping up” old solution instead of replacing it, and a case that has not been replaced for months.
• Wearing lenses beyond their recommended time. A monthly lens used for two months, a daily lens worn again the next day.
• Smoking, and lenses bought without fitting and follow-up by a professional.

The warning signs

A red and painful eye in a contact lens wearer is treated as keratitis until proven otherwise. The signs that require an examination the same day:

• Pain that persists or increases even after removing the lens.
• Strong light sensitivity and tearing.
• Blurred or reduced vision.
• A white or grey spot on the cornea, sometimes visible even to the naked eye.
• Discharge and swelling of the eyelid.

When these signs appear: remove the lens and do not put it back, keep the lens and the case (they can help identify the organism), do not instil leftover drops, and see an ophthalmologist or go to an eye emergency room. On the difference between an “ordinary” red eye and a dangerous one, see red eyes.

Bacteria, fungus or acanthamoeba

Bacteria are the most common cause. The best-known organism in lens wearers is Pseudomonas, which is characterised by particularly rapid progression – sometimes within a day. Pain, redness and the white spot usually appear quickly.

Fungi are rarer, and sometimes follow an injury from plant material or lens wear in a hot, humid environment. They develop more slowly, and the diagnosis is often delayed because the infection does not respond to antibiotic drops.

Acanthamoeba is an amoeba that lives in water, and infection with it is almost always linked to contact between the lens and water. It is rare, but important to know about: the pain is particularly severe relative to what is seen at the examination, it can initially look like herpetic keratitis, and treatment lasts many months. Suspected acanthamoeba in a lens wearer whose lenses were exposed to water is a reason to see a cornea specialist directly.

How it is diagnosed

The diagnosis is made at the slit lamp with fluorescein dye, which shows the size of the defect, the depth of invasion into the cornea and the eye’s reaction. In significant infection – large, deep, close to the centre of vision, or not responding to treatment – a corneal scraping is taken for culture before or early in treatment, to identify the organism and its sensitivity to drugs. The lens and the case are sometimes cultured as well. When acanthamoeba or fungus is suspected, there are additional dedicated tests, such as confocal microscopy and PCR, performed in cornea centres.

Treatment

In bacterial keratitis broad-spectrum antibiotic drops are started immediately, at a very high frequency – in the first days sometimes every hour, day and night. In severe infections “fortified” antibiotic drops specially prepared by the hospital pharmacy are used, and sometimes admission is needed to keep up with the treatment schedule. The culture results guide further treatment. Steroid drops, which reduce inflammation and scarring, are considered only at a later stage, once the infection is under control and under the direction of a cornea specialist – never on one’s own initiative. On the correct use of antibiotic drops, see antibiotic eye drops.

In fungal keratitis antifungal drops are used, sometimes with oral treatment as well; treatment is longer and requires close follow-up.

In acanthamoeba treatment is based on dedicated antiseptic drops that act against the amoeba and its cysts, and usually lasts six months or more, with follow-up in a cornea centre.

In all types, lenses stay out of the eye until full recovery and the doctor’s approval.

What happens afterwards: scarring, vision and transplantation

Most cases of keratitis that are diagnosed and treated early heal with a good outcome. An infection that went deep or involved the centre of the cornea can leave a scar that blurs vision or creates irregular astigmatism. Some scars improve over time; others are managed with special rigid contact lenses, with superficial laser (PTK), or – when the scar is deep and significantly affects vision – with a corneal transplant. In rare cases of an infection that does not respond to treatment or extreme thinning of the cornea, an urgent transplant is needed to save the eye.

The rules that prevent most cases

• Do not sleep in lenses, not even for a nap.
• Lenses and water never meet: do not rinse a lens or case in tap water, and do not shower or swim with lenses in. If you must swim with lenses, use daily disposables under tight-fitting goggles and throw them away straight afterwards.
• Wash and dry your hands before every contact with a lens.
• Fresh solution every time, without “topping up” old solution; replace the case regularly.
• Replace lenses according to their intended wearing time – and throw daily lenses away after one day.
• Have lenses fitted by a professional and attend periodic check-ups.
• Red and painful eye = remove the lens and be examined the same day.

Anyone who finds these rules hard to keep, or who has already had keratitis, can discuss alternatives to lenses with their ophthalmologist – glasses, or laser vision correction or lens implantation, where suitable.

When to get examined

A red, painful or light-sensitive eye in a contact lens wearer requires an examination the same day – in an eye emergency room or with an available ophthalmologist. After an episode of keratitis, or when a scar remains that affects vision, continued follow-up with a cornea specialist is appropriate. Prof. Michael Mimouni is a cornea specialist, and the examination assesses the state of the cornea, any remaining scar, and the options for restoring vision. Get in touch to arrange an examination. On other eye diseases, see eye diseases.

The information on this page is general and not a substitute for a personal examination and medical advice. Diagnosis and treatment are determined only after a full eye examination. In case of severe pain or reduced vision, seek urgent examination.