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Two-color pupillometry in enhanced S-cone syndrome caused by NR2E3 mutations
Journal article   Open access   Peer reviewed

Two-color pupillometry in enhanced S-cone syndrome caused by NR2E3 mutations

Frederick T Collison, Jason C Park, Gerald A Fishman, Edwin M Stone and J Jason McAnany
Documenta ophthalmologica, Vol.132(3), pp.157-166
06/2016
DOI: 10.1007/s10633-016-9535-0
PMCID: PMC6088747
PMID: 27033713
url
https://www.ncbi.nlm.nih.gov/pmc/articles/6088747View
Open Access

Abstract

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 patients who have enhanced S-cone syndrome (ESCS) due to NR2E3 mutations. Four patients with ESCS (ages 16-23 years) participated in the study. Subjects were tested with long- and short-wavelength single-flash full-field ERG stimuli under light-adapted conditions. They were also tested with an established pupillometry protocol involving 1-s duration, long- and short-wavelength stimuli under dark- and light-adapted conditions. The PLR was measured as a function of stimulus luminance. Transient PLRs were measured under all conditions, and sustained PLRs were 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 of the same photopic luminance, with three of four 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 lower than normal 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" responses. 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.
Electroretinography - methods Reflex, Pupillary - radiation effects Humans Male Reflex, Pupillary - physiology Young Adult Vision Disorders - physiopathology Color Vision - physiology Light Adult Female Retinal Ganglion Cells - physiology Eye Diseases, Hereditary - physiopathology Retinal Degeneration - genetics Retina - physiopathology Retinal Cone Photoreceptor Cells - physiology Dark Adaptation - physiology Retinal Degeneration - physiopathology Orphan Nuclear Receptors - genetics Eye Diseases, Hereditary - genetics Vision Disorders - genetics Retinal Rod Photoreceptor Cells - physiology Adolescent Mutation Photic Stimulation

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