J Maguire1, M McKibbin2, K Khan2, S Kohl3, M Ali4, D McKeefry1. 1. a School of Optometry and Vision Sciences , University of Bradford , Bradford , West Yorkshire , UK. 2. b Department of Ophthalmology , St. James's University Teaching Hospital , Leeds , UK. 3. c Molecular Genetics Laboratory, Institute of Ophthalmic Research, Centre of Ophthalmology , University Clinics Tubingen , Tubingen , Germany. 4. d Section of Ophthalmology and Neuroscience, Leeds Institute of Biomedical and Clinical Sciences , University of Leeds , Leeds , UK.
Abstract
PURPOSE: Congenital achromatopsia or rod monochromatism is a rare autosomal recessive condition defined by a severe loss of cone photoreceptor function in which rods purportedly retain normal or near-to-normal function. This report describes the results of electroretinography in two siblings with CNGB3-associated achromatopsia. METHODS: Full field light- and dark-adapted electroretinograms (ERGs) were recorded using standard protocols detailed by the International Society for Clinical Electrophysiology of Vision (ISCEV). We also examined rod-mediated ERGs using series of stimuli that varied over a 6 log unit range of retinal illuminances (-1.9-3.5 log scotopic trolands). RESULTS: Dark-adapted ERGs in achromatopsia patients exhibited severely reduced b-wave amplitudes with abnormal b:a ratios (1.3 and 0.6). In comparison, the reduction in a-wave amplitude was less marked. The rod-mediated ERG took on an electronegative appearance at high-stimulus illuminances. CONCLUSION: Although the defect that causes achromatopsia is primarily in the cone photoreceptors, our results reveal an accompanying disruption of rod function that is more severe than has previously been reported. The differential effects on the b-wave relative to the a-wave points to an inner-retinal locus for the disruption of rod function in these patients.
PURPOSE:Congenital achromatopsia or rod monochromatism is a rare autosomal recessive condition defined by a severe loss of cone photoreceptor function in which rods purportedly retain normal or near-to-normal function. This report describes the results of electroretinography in two siblings with CNGB3-associated achromatopsia. METHODS: Full field light- and dark-adapted electroretinograms (ERGs) were recorded using standard protocols detailed by the International Society for Clinical Electrophysiology of Vision (ISCEV). We also examined rod-mediated ERGs using series of stimuli that varied over a 6 log unit range of retinal illuminances (-1.9-3.5 log scotopic trolands). RESULTS: Dark-adapted ERGs in achromatopsiapatients exhibited severely reduced b-wave amplitudes with abnormal b:a ratios (1.3 and 0.6). In comparison, the reduction in a-wave amplitude was less marked. The rod-mediated ERG took on an electronegative appearance at high-stimulus illuminances. CONCLUSION: Although the defect that causes achromatopsia is primarily in the cone photoreceptors, our results reveal an accompanying disruption of rod function that is more severe than has previously been reported. The differential effects on the b-wave relative to the a-wave points to an inner-retinal locus for the disruption of rod function in these patients.
Authors: Revital Bronstein; Elizabeth E Capowski; Sudeep Mehrotra; Alex D Jansen; Daniel Navarro-Gomez; Mathew Maher; Emily Place; Riccardo Sangermano; Kinga M Bujakowska; David M Gamm; Eric A Pierce Journal: Hum Mol Genet Date: 2020-04-15 Impact factor: 6.150