[Use of botulinum toxin in ophthalmology]

Botulinum toxin A injection in essential blepharospasmus and hemifacial spasmus is an important alternative to surgical therapy. The toxin is injected into the lateral parts of the lower and upper lid in single doses of one to two nanograms under electromyographic control. The effect is visible after a few days and lasts for several months. The procedure can be repeated several times. A second important application of botulinum toxin A is strabismus. In paralytic strabismus the contracture of the antagonist of the paralyzed muscle can be weakened by local injection of botulinum toxin by means of a needle electrode under electromyographic control. Thus the contracture of the homolateral antagonist can be overcome and not seldom singular binocular vision obtained again. In cases of moderate pareses which recover spontaneously the muscle weakening effect of the toxin on the antagonist helps to restore binocular single vision. In cases of chronic paralytic strabismus the toxin injection into the antagonist facilitates the surgical intervention on the paralyzed muscle. In concomitant strabismus botulinum toxin A is above all valuable in small angle cases, in sensory strabismus, in cases of over- or undercorrection after surgery, and these especially in adults. In congenital esotropia, in commitant squints with large angles and in chronic or intermittent exotropia surgery is the preferred modality of treatment. The best results are obtained with repeated small doses. Generally a 65% reduction of the strabismus angle after two to three injections can be expected. With injections into the lids and the extraocular muscles no general systemic side effects has been observed.