Author’s Disclosure Block: Annie Lam-Nguyen, none; Anna Polosa, none; Mélanie Hébert, none; Christof Karl Hänsli, none; Marie-Lyne Bélair, none; Marie-Josée Aubin, none 

Abstract Body 

Purpose: The Purpose: of this study is to identify precursor signs of BSCR on the full-field electroretinogram (ffERG). Study Design:  A retrospective analysis of the clinical and paraclinical data, including imaging modalities and ffERG, collected in a database of 100 patients with BSCR in the HMR uveitis cohort was performed. Methods: Patients were categorized according to the clinical presentation at onset, as either typical or atypical, defined as absence of typical birdshot lesions at presentation, based on the classification criteria developed by the Standardization of Uveitis Nomenclature (SUN) Working Group. The demographic, clinical and ffERG values of patients were examined. Widefield pseudocolor fundus photography (Optos, Dunfermline, United Kingdom) along with clinical evolution from patient files were reviewed and analyzed chronologically. The ffERG waveforms were then analyzed and quantified with Prism (GraphPad Software Inc., New York City, NY). Results: Out of 100 patients, 11 cases were atypical BSCR defined as absence of typical birdshot lesions at presentation. Most of the patients in the atypical group were female (82%). Most patients were also under systemic corticosteroids (91%) and mycophenolate mofetil (MMF) (64%). FfERG showed an improvement in retinal function in 45% of patients under medication. Over time, 4 (36%) of the 11 cases developed typical birdshot lesions (i.e. confirming BRSC diagnosis) and had a similar f fERG response, a cone and rod anomaly, which was present prior to the apparition of birdshot lesions. These lesions appeared one year after a presumed diagnosis of BSCR in three of these cases and five years later in one of these cases. Median follow-up time was 4 [3, 11] years overall, while among the cases who eventually developed lesions, it was 9 [4, 16] years compared to 4 [3, 6] years among those who have not yet developed lesions (p=0.085). The patients that do not have typical birdshot lesions to date had other type of anomalies such as vasculitis, cystoid macular edema, optic disc edema and RPE changes on the eye fundus examination, photography and angiography pictures. Conclusion: Although more analysis is needed, the ffERG could potentially help detect patients at risk of developing lesions and inform the diagnosis and management of BSCR.