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Omar Abdul Rahman Mahroo, Ambreen Tariq, Taha Bhatti, Ting Shen, Katie M Williams, Christopher J Hammond, Pirro G Hysi; Towards elucidation of the myopia signalling cascade: association of human cone system electrophysiological response parameters with a myopia susceptibility polymorphism. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1097. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Genetic associations with myopia have been identified, but mechanisms by which they might confer susceptibility are not known. The strongest association (rs524952) is near a gene coding for a protein forming gap junctions in the retina (GJD2). We tested the hypothesis that this locus might be associated with alterations in retinal electrophysiological responses.
Full-field electroretinograms (ERGs) were recorded from healthy adult volunteers from the TwinsUK cohort. Stimuli were delivered through pharmacologically dilated pupils using the Espion ColorDome (DiagnosysLLC, Lovell, MA, United States), and conformed to international standards. Responses were recorded using conductive fibre electrodes placed in the lower conjunctival fornix. Where response parameters (amplitudes and implicit times as specified by the International Society for the Clinical Electrophysiology of Vision (ISCEV) standards for full-field electroretinography) were available for both eyes, these were averaged. Genotypes were obtained using the Illumina Human 660-Quad array and were imputed up to the 1000 Genomes Project haplotype. Association testing was performed using a mixed linear model with electrophysiological parameters as the outcomes and allelic dosage at this locus (rs524952) as a predictor, adjusting for age, sex and inter-individual relatedness.
Genotype data and recordings were available from 153 subjects (95% were female; mean (SD) age was 64.3 (9.8) years). Of the ISCEV parameters for photopic responses, significant associations were found with the locus of interest for a number of parameters as follows: photopic 30 Hz flicker peak amplitude (p=0.017) and implicit time (p=0.026); photopic standard flash b-wave amplitude (p=0.017) and implicit time (p=0.035). Of the parameters for scotopic ERGs, no significant associations were found.
The findings suggest associations between cone-driven (but not rod-driven) retinal electrophysiological parameters and the genetic polymorphism most strongly linked to myopia. These ERG parameters derive from cone-driven inner retinal neurons. Axial length elongation is known to be driven by retinal signalling, and this novel finding supports the hypothesis that alterations in cone system signalling may contribute to myopia development.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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