Surgical Dosing for V-Pattern Exotropia

Introduction. Consensus is lacking around optimal surgical strategies to correct V-pattern exotropia (VXT).

Study Design. Comparative interventional case series.

Methods. Consecutive patients with VXT undergoing strabismus surgery between 2014 and 2025 were reviewed. Incomitance of at least 15D between sursumversion and deorsumversion was considered V-pattern. Surgeries were performed by two surgeons using identical technique.

Outcomes. Surgical alignment effect.

Results. Fifty-five patients (36 children, 19 adults) underwent horizontal rectus muscle surgery: inferior oblique (IO) recession (n=12), superior transposition of lateral rectus muscles (n=20), their combination (n=10) and no modifications (n=13).Surgery reduced average primary gaze exotropia in all groups from 29±11Δ to 8±8Δ (standard deviation p < 0.001), irrespective of pattern collapse. There was 6.0 Δ mean postoperative exodrift after 2.1±2.0 years following surgery. Pattern decreased in all groups from: 22±8Δ to 10±8Δ by IO recession, 22±6Δ to 3±6Δ by horizontal rectus transposition, 30±10Δ to 5±13Δ by the combination, and 16±2Δ to 6±7Δ with no modifications. The combined procedure yielded greatest pattern reduction. Transpositions of ½ and ¾ tendon-width yielded similar effects on pattern.  Linear regression showed a significant correlation between lateral rectus recession and exotropia reduction (p < 0.001), accounting for 40% of variance. However, surgical effect was smaller than predicted by Parks’ tables.

Conclusion. IO recession, LR transposition and their combination reduce pattern in VXT, with the greatest effect when combined. Horizontal rectus recession alone also reduces the pattern, though to a lesser extent. Horizontal rectus recession dose need not be adjusted for pattern collapse. Early overcorrection is recommended.