Walsh & Hoyt: Botulinum Toxin Treatment of Nystagmus

An approach to treatment of nystagmus that has gained some popularity is injection of botulinum toxin into either the extraocular muscles or the retrobulbar space. Using both techniques, Ruben and colleagues reported improvement of vision in most of their 12 patients with a variety of diagnoses. The major side effect was ptosis. However, eye movements were not systematically measured and compared before and after injection. Repka and colleagues also described improvement of vision following retrobulbar injection of botulinum toxin in six patients and documented the effects on eye movements. The main reservation expressed by these authors was the temporary nature of the treatment and the necessity for repeated injections, with their attendant risks. We measured binocular eye rotations in three planes before and after monocular injection of botulinum toxin either into the horizontal recti, or into the retrobulbar space. Nystagmus was abolished or reduced in the treated eye for about 23 months, but no patient was pleased with the results because of ptosis, diplopia, increase of nystagmus in the noninjected eye or, in one patient, filamentary keratitis. No patient that we studied elected to repeat the procedure.