Role of botulinum toxin A in surgically overcorrected exotropia

The purpose of this study was to define the role of botulinum toxin type A (BTXA) in surgically overcorrected exotropia.

A retrospective review was performed using the BTXA clinic database of more than 3500 patients to identify patients with a consecutive esotropia.

Sixty patients met the inclusion criteria; the patients' ages ranged from 5 to 80 years. Before toxin treatment, an average of 1.8 operations had been performed per patient. The mean distance deviation was 17 PD base out and near deviation was 18 PD base out. The time from the last operation to an injection of BTXA averaged 28.3 months. We divided our patient population into 2 groups: those with fusion potential and those with no expected fusion potential. Of the 36 patients with fusion potential, 15 patients achieved and maintained good ocular alignment and resolution of their diplopia with an injection of BTXA. In the 24 patients with no expected fusion potential, 4 patients (17%) achieved and maintained good alignment with an injection of BTXA. Although they were not cured, 10 additional patients chose to have repeated BTXA injections to maintain their ocular alignment, whereas only 2 patients required occlusive methods to eradicate intractable diplopia. Five patients had additional surgery, of which 3 patients obtained a functional result.

BTXA has a role in surgically overcorrected exotropia for patients in whom a functional result may be obtained. BTXA is of less value for patients with poor binocular function. It has proved especially useful as a treatment given only once for 42% of patients who could regain high-quality stereopsis. The safety and ease of administration of this treatment add to its merit.