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Adriana Berezovsky, Daniel M. Rocha, Paula Y. Sacai, Sung S. Watanabe, Nivea N. Cavascan, Solange R. Salomao; Visual Acuity and Retinal Function in Patients with Bardet-Biedl Syndrome. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6074.
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© ARVO (1962-2015); The Authors (2016-present)
Bardet-Biedl syndrome is a genetically multisystem disorder that causes severe visual impairment. Retinitis pigmentosa (RP), hypogonadism, digit and renal abnormalities, obesity, and a variable degree of mental retardation characterize the disease. Ocular manifestations of Bardet-Biedl syndrome include early and severe rod-cone dystrophy usually causing legal blindness in the second decade of life. The purpose of this study was to analyze visual acuity (VA), full-field electroretinogram (ERG) findings in patients with Bardet-Biedl syndrome phenotype.
A consecutive group of 23 patients with Bardet-Biedl syndrome (15 males), with ages ranging from 6-36 years (mean=15.8±6.4; median=14.7) had their monocular visual acuity measured using the ETDRS chart, retinal function evaluated by standard full-field ERG and dark-adapted thresholds assessment. History of consanguinity was found in 11 (47.8%) patients. Out of 23 patients, 21 (91.3%) had obesity, 18 (78.3%) presented digital anomalies, 18 (78.3%) had mental retardation and 7 (30.4%) had renal anomaly. Pearson correlation was performed between VA in the better-seeing eye and age.
Visual acuity in the better-seeing eye was 20/40 or better in 5 patients (21.7%), 20/50-20/150 in 13 (56.5%) patients; 20/200-20/400 in 2 (8.7%) patients and worse than 20/400 in one (4.3%) patient. Two patients were uncooperative for visual acuity measurement. Mean VA in the better-seeing eye was 0.7 ±0.6 logMAR (20/100, Snellen equivalent) and 0.9±0.6 logMAR (20/160, Snellen equivalent) in the worse-seeing eye. Scotopic rod and maximal responses were non-detectable in 21 (91.3%) patients and non-detectable cone responses were found in 15 (65.2%) patients. Elevated dark-adapted visual thresholds were found in all 19 patients who were able to be assessed, with 10 (52.6%) patients showing thresholds higher than 30dB. A significant correlation was found between age and VA (r=0.79; P=0.00002). No statistical differences were found in either VA or ERG parameters between consanguineous and non-consanguineous patients.
In a relatively young cohort of patients with Bardet-Biedl syndrome, only 21% had vision of 20/40 or better. ERG scotopic responses were absent in the vast majority of cases with remaining cone responses in one third of them. These results confirm the early deleterious effect in retinal function and visual acuity caused by this condition.
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