Purchase this article with an account.
Frances J. Corkin, Ronald M. Hansen, Margaret A. Kenna, Heidi L. Rehm, Anne Moskowitz, Abigail Wilkins, Anne B. Fulton; Scotopic Sensitivity in Pediatric Patients with Usher Syndrome. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4362.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
In pediatric patients with a genetic diagnosis of Usher Syndrome we evaluated scotopic retinal function for significant change with age.
Eighteen patients with a genetic diagnosis of Usher Syndrome (MYO7A, n=11; CDH23, n=1; USH2A, n=5; CLRN1, n=1) were studied. Age at the first test ranged from 6 months to 17 years. Dark adapted thresholds for detecting 10° diameter, 50 ms duration stimuli presented 20° to the right or left of a central fixation target were estimated using a two-alternative, forced choice method. In thirteen patients, thresholds were measured longitudinally (2 to 6 tests, median=4) for up to 14 years. In the remaining five patients, thresholds were measured only once. Scotopic electroretinographic (ERG) responses to a ~3 log unit range of full-field stimuli were recorded in 15 of the patients; b-wave sensitivity was characterized by the stimulus that produced a half maximum response.
At the first test, thresholds were measurable in all and ranged from normal to significantly elevated (2.77 log units), with the majority at least a log unit elevated. In 12 of 13 patients with longitudinal data, threshold remained relatively stable over the course of the study. One MYO7A patient showed a 1.74 log unit loss of sensitivity over a 4 year period. Of the 15 patients who had ERG tests, responses were markedly attenuated in six. In the nine who had ERG stimulus-response data that could be analyzed, b-wave sensitivity was reduced a median of 1.59 (range: 0.75 to 2.44) log units. The deficit in b-wave sensitivity and the deficit in dark adapted threshold were correlated (r=0.84; df=9; p=<0.005).
Scotopic sensitivity, although abnormal in most, remains remarkably stable in this sample with Usher Syndrome. The dark adapted threshold allows quantitative assessment of retinal sensitivity even in those with markedly attenuated ERG.
This PDF is available to Subscribers Only