Stage III Intraoperative Adjustmentof Eye Muscle Surgery (Under General Anesthesia) for Neuroparalytic and Mechanical (Restrictive) Incomitant Strabismus: Report of Results in a Series: Outcomes in 20 Eye Muscle Surgeries in Twelve Patients.

Abstract

Techniques for the adjustment of surgery intraoperatively (especially those termed Stage I and II techniques) have proven maximally successful in improving surgical results for comitant strabismus. Stage III adjustments (end-operative) have been described but not studied. In a retrospective study of 20 eye muscle procedures in 12 patients with neuroparalytic and mechanical strabismus, the usefulness of various intraoperative adjustment techniques Stage I, II, and III was investigated for the first time. Stage I adjustments (adjusting the surgical plan based on the binocular misalignment following induction) were not helpful. Stage II adjustments (R. Bedrossian technique: adjusting the amount of surgery performed to create an actual change in binocular alignment under anesthesia matching the change in alignment desired clinically) were appropriate for horizontal mechanical and (all) vertical cases but not appropriate for horizontal neuroparalytic cases. Stage III adjustments, at the end of surgery, were appropriate in virtually all cases (20 muscles, 12 patients). Significant overcorrection, well beyond the theoretically ideal final intraoperative binocular alignment of 30 PD (prism diopters) was appropriate in all cases, but varied with type of case. Verticals (all) required a 5-10 PD overcorrection. Horizontal mechanical cases required a 22-30 PD overcorrection. Horizontal neuroparalytic cases required a 15-38 PD overcorrection, in the last group, in each case, graded according to the presence of contractures and the size of the preoperative deviation. The use of Stage III (and Stage II as noted above) adjustments brought postoperative binocular alignment to orthotropia +/- 10 PD in all cases, the conventional standard for satisfactory results in strabismus surgery.