The role of botulinum toxin in decompensated strabismus

The surgical management of decompensated strabismus is well described. Conservative treatment may employ the use of lenses and prisms. However, the use of botulinum toxin in decompensated squint is poorly documented. In these patients, with the potential for fusion, botulinum toxin may serve to stabilize the ocular alignment by bringing the images within the fusion range.

The aim of this study was to assess the role of botulinum toxin in the treatment of decompensated squints.

A retrospective case series involving 92 patients with decompensated squints between December 1990 and July 2005. Botulinum toxin was injected into the lateral rectus in 45 cases and into the medial rectus in 47. This was performed under local anesthesia in 74 cases, the remainder with ketamine anesthesia. Patients were assessed preoperatively at 2 weeks, 4 months, and a minimum of 12 months postoperatively. We defined successful treatment where the resultant stabilized deviation was less than or equal to 10 prism diopters with resolution of diplopia.

In this study, 47 patients had a decompensated microesotropia and 45 had a decompensated exophoria. We found that 27 (29.3%) patients were asymptomatic following injection of botulinum toxin. Fourteen (15.2%) patients were better controlled and did not require further intervention. Subsequent surgery was performed in 45 patients (48.9%).

Our results suggest almost half of those patients requiring treatment for decompensated squint benefit from botulinum toxin, without requiring surgical intervention. This approach is less invasive and allows potential for recovery of binocular function.