TREATMENT OF CORNEAL HEALING PROBLEMS WITH BOTULINUM TOXIN

 

Dr. S. Kraft

 

Patients who have various diseases of the cornea (the “watchglass” at the front of the eye) may develop loss of the covering (or surface) layer, known as the epithelium.  This leads to pain and irritation, as well as reduced vision. When treatment of the cornea condition does not result in successful healing of the defect in the surface layer, it may be necessary to shut the eye to allow proper healing.

 

In the past this required minor surgery in which the eyelids are temporarily closed using stitches (tarsorrhaphy).  The eyelids are reopened once the cornea is healed.

 

An alternative to surgery on the eyelids is the use of botulinum toxin (BotoxTM or XeominTM) to create a temporary closure of the eye.  Small amounts of the drug are injected into the upper eyelid and under the brow above the eyeball.  This leads to a painless droop (“ptosis”) of the upper eyelid which nicely covers the cornea throughout the day and night. This approach has the advantage of allowing the surgeon to easily check the status of the cornea by simply lifting the drooping eyelid.  This contrasts with the situation after the surgery option, where the view of the cornea can be less than optimal since the eyelids are stuck together by the surgery.

 

BotoxTM (distributed and licenced by Allergan, Inc.) and XeominTM (distributed and licenced by Merz Pharmaceuticals) are purified preparations of botulinum toxin.   Excessive amounts of this substance can cause food poisoning and weakness in humans.  However, the amount that is injected into the eyelids to induce a droop of the eyelid is 300 times smaller than the dose that causes poisoning.  No patient has had poisoning from this drug after being treated with injections into the eyelid.

 

There are rare instances of side effects:

 

1.   Intermittent tearing can occur as the tear film is not pumped efficiently into the tear sac. (1 in 50)  This usually resolves within 4 to 6 weeks.

 

2.   Rarely, the drug can reach the muscles in the eye socket that move the eye and cause double vision or a misalignment (strabismus) for a few days (risk 1 in 200). 

 

3.   Bleeding into the socket as a result of the injection, which is usually controllable with pressure (1 in 100).