Dysthyroid Optic Neuropathy in Graves' Orbitopathy: Insights from a Single Centre and Limitations of the Radiological Indices.

Abstract

Introduction: Close to 50% of patients with Graves' disease have associated ocular involvement, of which dysthyroid optic neuropathy (DON) is prevalent in 3-5% of patients. The response to intravenous glucocorticoids in DON is dependent on early diagnosis. The purpose of this study was to assess the efficacy of various radiological indices (Barrett's index, Nugent index) in predicting DON and treatment response or relapse in this population.

Methods: This was a retrospective study that included patients presenting with clinically active Graves' orbitopathy (GO) between January 2005 and June 2021 to our hospital. Demographics, clinical presentation, biochemical parameters, risk factors, comorbidities, and radiology data were collected and analysed.

Results: Fifty-eight orbits from 29 patients were assessed. A higher Barrett's index was associated with DON (61.4% vs 51.1%, P = 0.03), lower glucocorticoid responsiveness (63.7% vs 54.2%, P = 0.043), and the need for surgical intervention (62.85% vs 49.3%, P = 0.001). Nugent index ≥1 was significantly associated with sight-threatening GO (48.2% vs 22.2%, P = 0.02) and higher glucocorticoid requirements (54.8% vs 23.8%, P = 0.04). A cut-off of 58% for the Barrett's index (AUC 0.705, 95% CI 0.545-0.865) was suggestive of DON, with a sensitivity of 60% and a specificity of 68.8%.

Conclusions: This is the first comprehensive assessment of patients with GO among Indians with active disease. The Barrett's index threshold was defined in our population to facilitate objective early identification of DON. This index shows promise for early diagnostic sub-categorisation in DON among Indians; however, its low sensitivity limits its widespread use.