Cause of cornea erosions
Usually an injury to the cornea surface, such as a scratch from a baby's fingernail, triggers the problem. Once disturbed, the delicate cells lining the cornea surface seem not to heal properly, causing a weakness that may recur the erosions return is unpredictable, uninvited and unwelcome! Some patients have a genetically-programmed disorder of the cornea surface called a dystrophy for example map-dot- fingerprint dystrophy. In some people no cause is ever found.
Symptoms of a cornea erosion
The main symptom is eye pain which typically begins on waking in the morning. It can also begin at night during sleep. This is because the eyelids stick to the surface layer of the cornea when they are closed during sleep. When the patient wakes up in the morning (or during the night), the eyelids open suddenly and pull the abnormal surface layer away from the underlying cornea. This creates minute erosions or blisters that are painful. The pain usually lasts only a few minutes. However severe cases can be painful for long periods during the day. A bad blister may get infected although this is infrequent.
High magnification photograph of the minute cornea surface blisters that cause cornea erosions.
Treatment for cornea erosions
During a bad episode, I will prescribe antibiotic drops and to make you comfortable a therapeutic contact lens that stays on the eye acting as a bandage until you are better. I may also give you a supply of anaesthetic drops which are extremely effective for pain relief but must be used sparingly or they may slow healing.
Lets consider prevention how can cornea erosions be prevented ? The initial and easiest treatment is to apply a thick lubricating ointment to your eye last thing at night before sleep. Suitable ointments are Simple Eye Ointment and Lacrilube which in the UK may be bought from pharmacies without a doctors prescription. These do not contain medicated ingredients which might cause side effects. They are based on lanolin and simply coat the surface layer of the cornea, preventing the eyelids from sticking to it overnight. This stops the formation of painful blisters. The ointment must be applied every night for several weeks to allow the condition to settle. It can then stopped and re-instituted if the problem returns.
If ointment doesnt work other treatments are available. These are used in sequence from simple and non-surgical contact lens wear to the sophisticated and surgical technology of the excimer laser. Some treatments are especially appropriate for particular patients- see below. An extended wear soft contact lens may be used as a bandage. It is worn day and night and not removed, protecting the cornea surface from eyelid rubbing until the erosion has healed. However it does not cure the underlying weakness which may return later. If you ordinarily wear contacts or need glasses to see, your prescription may be incorporated into the bandage lens and this approach may suit you.
The next step which is surgical but relatively low-key is chemical debridement of the cornea surface. Here a chemical is applied to the cornea to remove the lining after which the chemical is re-applied to the now-denuded surface. The effect is to roughen up the surface in a calculated way, so when the surface lining regrows which takes about 3 days it adheres more strongly than before and no longer forms erosions. The upside of this approach is that it is simple surgery with a low chance of causing complications the only likely problem is haze, a fine scar of the area in contact with the chemical. This is uncommon, usually has no effect on vision and anyway passes after a few months. Haze is far too subtle to be visible. The downside of chemical surgery is that it hurts for 2-3 days after and isn't always curative. It can be repeated if need be. This is a good treatment and usually works at either the first or subsequent attempts.
The most high-tech and surgical technology is a laser therapy called phototherapeutic keratectomy (PTK). This is done with an excimer laser the same type of laser used to correct glasses dependance sometimes combined with chemical debridement to increase the cure rate. The good news is that PTK may easily be combined with corrective eye laser treatment and so may appeal to you. However you should be aware that PTK hurts afterwards (it feels like a really bad erosion lasting a few days), there is a chance of haze (which may begin up to about a year later and be triggered by pregnancy or strong sunshine exposure so wear your shades on the beach and the ski slopes!) and the success rate is probably no greater than chemical debridement alone.
Finally the good news Eyesite surgeon Dr Simon Levy has looked after many patients with this disorder and has discharged most of them cured!
