Computed Tomography–Based Prediction of Exophthalmos Reduction After Deep Lateral Orbital Wall Decompression for Graves’ Orbitopathy
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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.
KeywordsComputed tomography Deep lateral orbital wall decompression Fat removal Graves’ orbitopathy The greater wing of the sphenoid Prediction
The authors wish to acknowledge Dr. Makoto Ito at Department of Radiology, Aichi Medical University, for assisting us in the interpretation of imaging studies. We also thank Editage (www.editage.jp) for English language editing.
All authors qualify for authorship based on contributions to the conception and design (YK, YT), acquisition of data (YK), literature search (YK, YT), and analyses and interpretation of data (all authors). All authors contributed to drafting the article and revising it critically for important intellectual content and final approval of the version to be published.
Compliance with ethical standards
Conflicts of interest
The authors declare that they have no conflict of interest.
Patient consent information and ethical approvals
This retrospective observational study was approved by the Institutional Review Board (IRB) of Aichi Medical University Hospital (application number 2016-H238) and adhered to the tenets of the Declaration of Helsinki and its amendments. The IRB granted a waiver of informed consent for this study on the basis of the ethical guidelines for medical and health research involving human subjects established by the Japanese Ministry of Education, Culture, Sports, Science, and Technology and the Ministry of Health, Labour, and Welfare. The waiver was granted because the study was a retrospective chart review, not an interventional study, and because it was difficult to obtain consent from patients who had been treated several years prior to the study. Nevertheless, at the request of the IRB, we published an outline of the study, which is available for public viewing on the Aichi Medical University Hospital website. This public posting also gave patients the opportunity to decline participation, although none of the patients did so. Personal identifiers were removed from all records prior to data analysis.