Evaluation of Visual Function and Needs in Adult Patients With Bardet–biedl Syndrome

In Brief Purpose: To assess the visual needs of the adult population with Bardet–Biedl syndrome (BBS) and to ensure that this is addressed by a national Bardet–Biedl Service. Methods: A cross-sectional analysis of all adults under a national BBS Clinic (Birmingham, United Kingdom) was performed using the BBS Ophthalmic Assessment Tool, a novel tool designed to capture the key elements of visual function, impact on lifestyle, and clinical findings relevant to BBS. Results: Sixty-two adult patients were confirmed to have BBS. Bardet–Biedl syndrome mutations were identified in 51, most commonly BBS1 (n = 35), BBS2 (n = 6), and BBS10 (n = 5). In 11 patients (18%), BBS had not been diagnosed until adulthood. Median visual acuity was hand motion (range, 0.0 logMAR–no perception of light). More advanced retinopathy was associated with increasing age, worsening visual acuity, and the presence of nystagmus. Forty patients (65%) had undertaken mainstream education with 29 (47%) achieving higher education; 7 patients (11%) had moderate or severe learning difficulties. Most (90%) were registered sight-impaired or severely sight-impaired patients. Conclusion: The BBS Ophthalmic Assessment Tool provides a wide-ranging assessment of ophthalmic status and vision-related needs of the BBS population. This evaluation demonstrates the spectrum of visual disability in this population and its correlation with worsening retinopathy over time. The retinopathy in Bardet–Biedl syndrome shows variable severity and clinical phenotype but with an electrodiagnostic evidence of retinal dysfunction being present in all cases. A Bardet–Biedl syndrome–focused retinopathy grading system and ophthalmic assessment tool are presented.