Strabismus surgery outcomes in eyes with glaucoma drainage devices

To report strabismus surgery outcomes in eyes with prior implantation of glaucoma drainage devices (GDD).

The medical records of patients who underwent strabismus surgery for ocular misalignment that developed after implantation of a GDD over a 13-year period at a single institution were examined retrospectively. Patient characteristics, deviation types, preoperative measurements, surgical procedures, and postoperative measurements were analyzed.

Of the 16 patients included, 14 had exotropia (34^Δ ± 16^Δ) and 11 had vertical deviations (15^Δ ± 7^Δ), of which 9 had concurrent exotropia and vertical deviations. Preoperatively, 9 patients had diplopia. The surgical approach was tailored to address the deviation most noticeable to the patient-horizontal, vertical, or both if the vertical component could be addressed by horizontal muscle supra- or infraplacement. Three patients underwent simultaneous horizontal and vertical surgery. All patients underwent strabismus surgery on an eye with a GDD. Surgical motor success (defined as horizontal deviation ≤10^Δ, vertical ≤4^Δ) was achieved in 42% of horizontal and 57% of vertical deviations. Postoperatively 74% of deviations decreased by ≥50% in magnitude. Diplopia resolved in 50% of patients who presented with preoperative diplopia. One patient had intraoperative bleb perforation, but none had postoperative hypotony at any follow-up visit. Only 2 required a second strabismus surgery.

Strabismus surgery with preservation of the filtering bleb following implantation of a glaucoma drainage device is a low risk procedure that can improve ocular alignment and related symptoms, despite a low motor success rate by standard criteria.