Computed Tomography-Based Prediction of Exophthalmos Reduction After Deep Lateral Orbital Wall Decompression for Graves' Orbitopathy.

Abstract

To examine the predictability of exophthalmos reduction using preoperative computed tomography (CT) in deep lateral orbital wall decompression for Graves' orbitopathy. This was a retrospective, observational, case-control study conducted at a single institution. Forty-three patients (43 orbits) who were treated with deep lateral decompression with (27 patients) and without (16 patients) fat removal. Multivariate linear regression analyses were used to identify factors influencing exophthalmos reduction 3 months postoperatively. Variables investigated included age; smoking history; history of corticosteroid therapy and/or radiotherapy; preoperative diplopia; width, depth, and height of the greater wing of the sphenoid bone (trigone); and volume of fat removed. The influence of these parameters on the area of the orbital opening was also analyzed. Trigone width and amount of fat removed were positively correlated with exophthalmos reduction (both, P < .050); none of the other variables exhibited significant correlations. The predictive equation for postoperative reduction in Hertel exophthalmometric values was 0.57 + 0.15 × trigone width (mm) + 1.1 × fat removed (cm3). Depth and height were positively correlated (both, P < .050) and width was negatively correlated (P = .0045) with orbital opening area. Trigone width and amount of fat removed were positive predictors of exophthalmos reduction after deep lateral decompression. Trigone width was inversely associated with orbital width, and results showed that larger exophthalmos reductions could be achieved in narrower orbits. This CT-based prediction method will assist preoperative decision-making regarding additional fat removal and/or removal of another orbital wall.