Dysthyroid optic neuropathy: a case series at a tertiary ophthalmic referral centre.

Abstract

To determine risk factors and treatment outcomes in dysthyroid optic neuropathy (DON) at a single tertiary ophthalmic centre. Retrospective audit of DON patients who have received intravenous methylprednisolone (IVMP) therapy at Royal Victorian Eye and Ear Hospital, Melbourne, Australia from July 2015 to October 2021. Study included 24 patients (58% female) with an average age of 59.8 ± 14.7 years at DON diagnosis. Majority (92%) had Graves' hyperthyroidism and 77% had a smoking history. At diagnosis, average visual acuity (VA) of worse eye was LogMAR 0.46, and 48% had relative afferent pupillary defect. Proptosis (89%) and diplopia (73%) were most commonly present at diagnosis. 78% showed predominantly extra-ocular muscle enlargement, and apical crowding (52%) on radiology. 38% (n = 9/24) responded to IVMP alone, 58% (n = 14/24) progressed to surgical orbital decompression. The average total cumulative dose of IVMP during DON treatment was 6.8 ± 1.9 g. 29% required further treatment after IVMP and surgical decompression, 4 (17%) had additional radiotherapy, and three (13%) required immuno-modulatory therapy. Average final VA was LogMAR 0.207, with all patients having inactive TED at final follow-up (mean 1.7 years). In refractory DON cases, 71% retained VA ≥ 6/9 and 48% had DON reversal. DON patients typically present in late 50s, with a smoking history and predominant extra-ocular muscle enlargement. High-dose IVMP fully resolved DON in only 38%. A considerable proportion required urgent orbital decompression. Most patients retained good vision at final follow-up.