A randomized comparative study of inferomedial vs. balanced orbital decompression. Analysis of changes in orbital volume, eyelid parameters, and eyeball position.

Background/objectives: The objective of this study is to investigate and compare changes in orbital volume, eyelid parameters, and eyeball position after inferomedial and balanced (medial + deep lateral walls) orbital decompression (OD) in patients with Graves' orbitopathy (GO).

Subjects/methods: Prospective interventional trial. Forty-two patients with inactive GO and clinical indication for OD were randomly assigned to inferomedial or balanced OD. Preoperative and postoperative Hertel exophthalmometry, standardized photography, and computed tomography were used to evaluate upper and lower eyelid margin reflex distances (MRD and MRD), orbital expansion, and changes in eyeball position.

Results: Clinical and radiological exophthalmometry improved significantly after OD with both surgical techniques (p < 0.001), but more so with balanced OD (p = 0.02). Concurrent eyeball descent (p = 0.01) and orbital volume expansion (p < 0.001) were observed with both techniques. The mean decompression volume was similar for the medial wall and the lateral wall but significantly smaller for the inferior wall (p < 0.05). Significant correlation coefficients were found for Hertel reduction vs. total decompression volume (p < 0.05). In the multivariate linear analysis, lateral wall decompression volume (LWDV) was predictive of exophthalmos reduction (p < 0.05). The two techniques produced a similar reduction in MRD and MRD. A significant correlation was also found between Hertel reduction and lower lid elevation (p < 0.05).

Conclusions: Both inferomedial and balanced OD successfully expanded orbit capacity, but the latter was more efficient at reducing exophthalmos probably due to the inclusion of the lateral wall. Upper and lower eyelid retraction improved after OD, but only lower eyelid elevation was correlated with exophthalmos reduction.