Changes in proptosis and eyelid position following orbital fat decompression for thyroid eye disease

BACKGROUND: Proptosis and eyelid retraction in thyroid eye disease (TED) affect both cosmetic appearance and psychological wellbeing. This study aimed to evaluate the outcomes of orbital fat decompression in patients presenting with proptosis and eyelid retraction. METHODS: We retrospectively reviewed 40 patients (79 eyes) with non-active TED who exhibited both proptosis and eyelid retraction. All patients underwent orbital fat decompression through a lower transconjunctival incision with release of the lower eyelid retractor to access the intraorbital space. Orbital fat was removed from the medial and lateral compartments. Changes in proptosis, marginal reflex distance (MRD)-1, and MRD-2 were recorded. Improvements per 1.0 cc of fat removal were calculated, and Pearson’s correlation analysis was performed. RESULTS: Mean postoperative improvements were 2.92 ± 1.47 mm for proptosis (P < 0.01), 0.21 ± 0.38 mm for MRD-1 (P = 0.33), and 1.27 ± 0.73 mm for MRD-2 (P < 0.01). For each 1.0 cc of removed orbital fat, improvements averaged 1.08 ± 0.48 mm in proptosis, 0.07 ± 0.38 mm in MRD-1, and 0.45 ± 0.28 mm in MRD-2. The volume of fat removed positively correlated with improvements in proptosis (r = 0.74) and MRD-2 (r = 0.63), but not MRD-1 (r = 0.17). CONCLUSIONS: Orbital fat decompression improves proptosis by approximately 1.1 mm per 1.0 cc of removed orbital fat. This quantitative relationship may help predict postoperative outcomes. The procedure is also effective in improving lower eyelid retraction.