Ocular motility changes after inferomedial wall and balanced medial plus lateral wall orbital decompression in Graves' orbitopathy: a randomized prospective comparative study.

Objectives: To compare the surgical outcomes of inferomedial wall orbital decompression (IM-OD) and balanced medial plus lateral wall orbital decompression (ML-OD) in patients with inactive Graves' orbitopathy (GO) with regard to exophthalmos reduction and ocular motility abnormalities.

Methods: Forty-two patients with inactive GO eligible for OD were randomly assigned to either the IM-OD or ML-OD groups. Pre and postoperative evaluations included Hertel exophthalmometry, sensory, and motor extraocular motility assessment, standardized photographs in the nine gaze positions, and computed tomography (CT) of the orbits. ClinicalTrials.gov: NCT03278964.

Results: Exophthalmometry reduction was statistically significant in both groups (p<0.001), but was greater in the ML-OD group (p=0.010). New-onset esotropia occurred in 11.1% and 23.5% of patients who underwent IM-OD and ML-OD, respectively, with no statistically significant difference in the frequency of pre and postoperative strabismus in either group. The mean increase in preoperative esotropia was 24±6.9 and 12±8.8 prism diopters in patients who underwent IM-OD and ML-OD, respectively. In the IM-OD group, abduction and elevation worsened at the first (p<0.05) and third (p<0.05) postoperative visits but were restored at 6 months. The versions did not change postoperatively with ML-OD. The preoperative CT-measured medial rectus muscle area predicted new-onset strabismus (p=0.023). Significant postoperative medial rectus muscle enlargement occurred in both groups (p<0.001). Restriction in elevation and abduction was significantly associated with enlarged inferior (p=0.007) and medial rectus muscle areas (p=0.002).

Conclusions: IM-OD is as safe as ML-OD with regard to new-onset strabismus, and represents a good alternative for patients who do not require significant exophthalmos reduction. ML-OD offers greater exophthalmos reduction and smoother postoperative recovery. Patients with preoperative enlarged medial rectus muscle on CT are at risk for new-onset esotropia, and preoperative esotropia is likely to increase after OD.