Change in eyelid parameters after orbital decompression in thyroid-associated orbitopathy

PURPOSE: To investigate quantitative changes in eyelid parameters after orbital decompression surgery in thyroid-associated orbitopathy using the PC-based program, Eyelid Analysis Software (EAS). METHODS: This study included 202 eyes of 109 thyroid-associated orbitopathy patients. Digital photographs of the patients in primary gaze were taken just before and after orbital decompression surgery, and exophthalmos degree was measured by Hertel exophthalmometry (Hertel Exophthalmometer SKU:52400; Oculus, Arlington, VA, USA). The custom-made PC-based software EAS (Biomedical Research Institute, Seoul, Korea) was used to analyze eyelid parameters. The 11 parameters included pupil to inferior eyebrow distance (PBD), margin reflex distance 1 (MRD1), margin reflex distance 2 (MRD2), palpebral fissure (PF), total lid length, upper and lower lid length, area, medial area, center area, and lateral area. RESULTS: Univariate linear regression analysis showed a significant positive association between amount of exophthalmos reduction and the following parameters: area (p = 0.007); MRD2 (p = 0.043); upper lid length (p = 0.045); lower lid length (p = 0.006); medial area (p = 0.045); and lateral area (p = 0.005). Multivariate linear regression analysis showed only two parameters, lower lid length (p = 0.022) and lateral area (p = 0.019) were associated with exophthalmos reduction. CONCLUSIONS: A reduction in the inferior lateral part of the eyelid (lateral area + lower lid length) occurred after orbital decompression surgery in patients with thyroid-associated orbitopathy.