Dose of medial rectus recessions for adult divergence insufficiency-type esotropia

Abstract

Purpose : To evaluate whether doses of bilateral medial rectus recessions greater than Parks’ tables yield superior outcomes for adult-onset divergence insufficiency.

Methods : As part of a prospective observation study of adult-onset divergence insufficiency type esotropia, with treatment at investigator discretion, 42 participants underwent bilateral medial rectus recessions. Dose was analyzed as the average total mm per muscle (surgery + adjustment if performed) and compared with standard Parks’ tables (based on preoperative distance esodeviation), as difference between dose performed and dose indicated by Parks’ tables. Each participant was classified having received Parks’ dose (within 0.5mm) or greater dose. Alignment was assessed by prism and alternative cover test at distance and near. Outcome was assessed at 10 weeks and 12 months. Success was defined as “rarely” or “never” diplopia in distance straight ahead gaze and reading. For patients classified as success, we calculated the mean difference between dose performed and dose indicated by Parks’ tables.

Results : Overall, 35 (85%, 95% CI: 71% to 94%) of 41 were classified as success at 10 weeks. Success was numerically greater in those receiving greater than Parks’ dose vs Parks’ dose (29 of 32 [91%] vs 6 of 9 [67%], difference 24%, 95% CI -5% to 60%). For the 35 successful cases, average dose of surgery performed on each medial rectus was greater than Parks’ tables by 1.0 mm (95% CI: 0.8 to 1.2mm, P<.0001). For the 16 cases performed on adjustable sutures, there were no advancements at adjustment, only further recessions (n=11) or no adjustment (n=5). Regarding longer-term over- or under-corrections (at 12 months), among 40 cases with outcome data, there was only 1 case (3%, 95% CI: 0.1% to 13%) with consecutive exodeviation>10pd at near (diplopia “sometimes”). Twelve (30%, 95% CI: 17% to 47%) had residual or recurrent distance esodeviation>2pd, of which 4 (33%) experienced more than rare diplopia at distance.

Conclusions : When performing bilateral medial rectus recessions for adult-onset divergence insufficiency-type esotropia, surgical doses greater than Parks’ tables appear to be a reasonable strategy, but our small number receiving Parks’ doses precluded conclusion that greater than Parks’ doses were superior. Higher surgical doses did not appear to be associated with longer-term consecutive exotropia.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.