Influence of surgical approach for decompression on lower eyelid position in thyroid eye disease

Purpose: Orbital decompression for thyroid eye disease (TED) has been noted to improve lower lid retraction by 0.5-1 mm. We hypothesize that orbital decompression via transconjunctival approach may lead to increased reduction in marginal reflex distance 2 (MRD2) as it involves division of the lower lid retractors. The purpose of this study is to evaluate relative changes in lower lid position for patients undergoing lateral and transconjunctival orbital decompression, respectively. Methods: In this cross-sectional study, all TED patients managed with lateral or transconjunctival orbital decompression for a 3-year period were screened for inclusion. Photographs taken in the primary position preoperatively and three months postoperatively were utilized to evaluate the MRD2 from each patient. Measurements were made utilizing NIH ImageJ software standardized to a corneal diameter. Hertel measurements of proptosis were obtained pre and postoperatively. The primary outcome measure was MRD2 in operative eyes. Results: A total of 131 (86 patients) operative eyes were included in the sample. Mean change MRD2 was not significantly different between the surgical groups (p = 0.07). In multivariate modeling, mean change in MRD2 was significantly associated with change in exophthalmometry, independent of surgical approach. Conclusions: The association between decrease in Hertel measurement and decrease in MRD2 is consistent with the existing literature on the topic. It appears that transconjunctival division of the lower eyelid retractors provides no additional benefit in reducing lower lid retraction relative to change in proptosis.