PURPOSE: To compare the measurements of macular thickness, intraocular pressure and RNFL and hormone parameters before and after antithyroid therapy in patients with Graves' Ophthalmopathy (GO). METHODS: A prospective observational study conducted at a tertiary care center. Patients with GO were included and scored (Clinical Activity Score, CAS) according to EUGOGO guideline. The participants underwent extensive ophthalmological examinations including intraocular pressure measurements with Goldmann applanation tonometry and RNFL with macular thickness evaluations via optical coherence tomography (OCT). Baseline and follow-up (24 weeks) hormone parameters including free T3, free T4, Thyroid stimulating hormone (TSH), Thyroid receptor autoantibodies (TRAbs) and intraocular measurements (RNFL, macular thickness, intraocular pressure) were performed and compared in the current study. RESULTS: Comparisons of baseline and follow-up biochemical parameters TSH, fT3, fT4, TRAbs, anti-TPO (p <
0.001). Although baseline score of CAS was mildly increased in all patients (0.5 ± 0.8 vs. 0.1 ± 0.4, p <
0.001) but it was significantly decreased after the antithyroid therapy. Mean intraocular pressure (14.9 ± 2.8 vs. 14.2 ± 1.9), RNFL (100.2 ± 9.05 vs. 99.9 ± 8.7) and macular thickness (274.7 ± 42.9 vs. 271.2 ± 43.3) were similar between baseline and after antithyroid therapy. And baseline RNFL measurements showed significant negative correlation with serum baseline TRAbs, antiTPO, fT3, fT4 (p <
0.05). CONCLUSION: Baseline serum fT3, fT4 and TRAbs in patients with Graves' Disease levels may be the prognostic factors in the evaluation of affecting intraocular structure, especially Retinal Nerve Fiber Layer, in patients with GO.