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Frederick T Collison, Jason C Park, Gerald A. Fishman, J Jason McAnany; Two-color pupillometry in enhanced S-cone syndrome. Invest. Ophthalmol. Vis. Sci. 2016;57(12):619. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of this study was to evaluate pupillary light reflexes (PLRs) mediated by rod, cone, and intrinsically photosensitive retinal ganglion cell pathways as indices of outer- and inner-retinal function in enhanced S-cone syndrome (ESCS) patients.
Four patients with ESCS (ages 16-23 years) participated in the study. Subjects were tested with long- and short-wavelength single-flash ERG stimuli under light adapted conditions. They were also tested with an established pupillometry protocol involving 1-second duration, full-field, long- and short-wavelength stimuli. The PLR was measured as a function of stimulus luminance (-4 log cd/m2 to 2.6 log cd/m2 under dark-adapted conditions and -1 log cd/m2 to 2.6 log cd/m2 under light-adapted conditions). Transient relative pupillary responses were measured under all conditions, and a sustained pupillary response was measured under the highest luminance dark-adapted condition.
Two-color light-adapted full-field ERGs demonstrated larger amplitude responses for short-wavelength stimuli relative to long-wavelength stimuli, with 3 of 4 ESCS patients having super-normal a-wave amplitudes to the short-wavelength stimulus. B/A wave ratios were reduced in all four cases. Transient PLRs elicited by low luminance stimuli under dark-adapted conditions (rod-mediated) were unrecordable, whereas the sustained PLRs elicited by high luminance stimuli (melanopsin-mediated) were normal. Cone-mediated PLRs were recordable for all four patients, but generally reduced in amplitude. However, the cone-mediated PLR was larger for the short-wavelength stimulus compared to the photopically matched long-wavelength stimulus at high luminances, a pattern that was not observed for control subjects. None of the PLR conditions demonstrated “super-normal” findings.
ESCS patients appear to have generally well-preserved cone- and melanopsin-mediated PLRs, indicating intact inner-retinal function. Two-color pupillometry demonstrates greater sensitivity to short-wavelength light under higher-luminance conditions and could complement the ERG as a tool for evaluating retinal function in ESCS.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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