Related Experiment Video
Updated: Aug 9, 2026

Correction of Presbyopia by Monocular Bi-Aspheric Ablation Profile
Published on: September 20, 2024
Unilateral surgery for exotropia with convergence weakness
S P Kraft1, A V Levin, R W Enzenauer
1Department of Ophthalmology, Hospital for Sick Children, Toronto, Ontario, Canada.
Abstract:
We prospectively studied 14 patients whom we treated surgically for exotropia (XT) with convergence weakness measuring at least 8 delta for distance (6 m) that increased at least 8 delta at near (1/3 m). Surgery involved lateral rectus recessions and medial rectus strengthenings (advancements or resections) to eliminate distance and near deviations and simultaneously collapse near-distance differences. The medial rectus was strengthened more than the lateral rectus was recessed; amounts were based on the near deviation. Minimum follow-up was 6 months after surgery. Preoperatively, the mean XT at distance was 18.3 delta (range, 8 to 35 delta) and at near 30.1 delta (range, 16 to 50 delta). At latest follow-up evaluations the mean distance deviation was 0.1 delta XT and at near 1.8 delta XT. The near-distance differences were reduced by a mean of 10.2 delta; the mean postoperative difference was 1.7 delta. Unilateral surgery for XT with convergence weakness biased to medial rectus strengthening and geared to near deviation can successfully collapse the near-distance differences while satisfactorily aligning both distance and near fixation. This surgery has low risk of creating long-term postoperative esodeviations at distance.
Related Concept Videos
Angle Closure Glaucoma: Treatment
Muscles of the Eye
Extraocular Muscles
The six extraocular muscles surround the eyeball and control its movements. They are responsible for a wide range of eye motions, including looking up, down, left, right, and rotating...

