Fixed Dose Inferior Oblique Recession Has Self-Adjusting Effect

This study aimed to determine the effect of a uniform dose of unilateral inferior oblique muscle (IO) recession on incomitant hypertropia.

Retrospective consecutive case series.

Thirty-three patients with incomitant hypertropia who underwent identical unilateral IO recession between June 2015 and June 2025.

Patients underwent unilateral IO recession by a single surgeon who reinserted the IO 4 mm posterior and 3 mm temporal to the temporal pole of the inferior rectus insertion. Hypertropia was measured in distant central and secondary gazes, and centrally at near. Surgical effects were evaluated by linear regression.

Postoperative hypertropia, incomitance, retreatment, and relationship of initial deviation to surgical effect.

Mean patient age was 40±27 (standard deviation) years, and follow-up averaged 448±562 days. Twenty patients had superior oblique palsy. Mean hypertropia in central gaze decreased after IO recession from 8.8±7.9Δ to 1.2±2.9Δ, and in contralateral gaze from 17.0±9.6Δ to 2.1±3.6Δ. Mean preoperative horizontal incomitance decreased after IO recession from 13.7±8.4Δ to 2.4±4.1Δ. Mean vertical incomitance decreased from 6.8Δ to 2.0±4.4Δ. Surgical effect was proportionately greater with greater preoperative hypertropia, resulting on average in nearly ideal correction of all hypertropia at distance in central, ipsilateral, contralateral, as well as in near gazes. This effect generally eliminated incomitance. Three (9%) patients required additional strabismus treatment.

Fixed-dose IO recession corrects a wide range of incomitant hypertropia in a self-grading manner, achieving excellent effect for a wide range of hypertropia and incomitance.