The influence of L-opsin gene polymorphisms and neural ageing on spatio-chromatic contrast sensitivity in 20–71 year olds

Abstract

Chromatic contrast sensitivity may be a more sensitive measure of an individual's visual function than achromatic contrast sensitivity. Here, the first aim was to quantify individual- and age-related variations in chromatic contrast sensitivity to a range of spatial frequencies for stimuli along two complementary directions in color space. The second aim was to examine whether polymorphisms at specific amino acid residues of the L- and M-opsin genes (OPN1LW and OPN1MW) known to affect spectral tuning of the photoreceptors could influence spatio-chromatic contrast sensitivity. Chromatic contrast sensitivity functions were measured in 50 healthy individuals (20-71 years) employing a novel pseudo-isochromatic grating stimulus. The spatio-chromatic contrast sensitivity functions were found to be low pass for all subjects, independent of age and color vision. The results revealed a senescent decline in spatio-chromatic contrast sensitivity. There were considerable between-individual differences in sensitivity within each age decade for individuals 49 years old or younger, and age did not predict sensitivity for these age decades alone. Forty-six subjects (including a color deficient male and eight female carriers) were genotyped for L- and M-opsin genes. The Ser180Ala polymorphisms on the L-opsin gene were found to influence the subject's color discrimination and their sensitivity to spatio-chromatic patterns. The results expose the significant role of neural and genetic factors in the deterioration of visual function with increasing age.

The association between L:M cone ratio, cone opsin genes and myopia susceptibility

“…Because females have two X chromosomes, L and/or M opsin exon 3 haplotype heterozygosity translates into a retina where there will be patches with two sets of L and/or M cones expressing different haplotypes, and these haplotypes could give rise to less-than-normally functioning opsin and/or altered spectral sensitivity. It has been shown that females with heterozygote mosaics will vary greatly in chromatic contrast sensitivity, depending on opsin haplotype ( Dees et al, 2015 ) and their L:M ratio ( Gunther & Dobkins, 2002 ). Those with haplotypes that code for more than two different L and/or M cones with large spectral separation and have a low, symmetrical L:M cone ratio, will have improved chromatic sensitivity ( Osorio & Vorobyev, 1996 ), but increased chromatic noise degrading signalling of high-spatial frequency information ( Barlow, 1982 ; Osorio, Ruderman, & Cronin, 1998 ).…”

“…All participants gave saliva samples (Oragene-DNA, OG-500, DNA Self-Collection Kit, DNA Genotek Inc., Ottawa, ON, Canada) for genetic analysis of their cone opsin genes. DNA was extracted, the L and M cone opsin genes were amplified by polymerase chain reaction (PCR), and exon 2, 3 and 4 were sequenced by a 3500 Genetic Analyzer (Applied Biosystems, Foster City, CA, USA), as described previously ( Dees, Gilson, Neitz, & Baraas, 2015 ). Single-nucleotide polymorphisms (SNP) genotyping by Sequenome MassArray (Sequenome Inc., San Diego, CA, USA) was used to analyse the opsin array composition ( Davidoff, Neitz, & Neitz, 2016 ).…”

Color Vision in Aniridia

“…Color vision was screened binocularly with the Hardy-Rand-Rittler 4th edition (HRR; Richmond Products, Albuquerque, NM, USA) pseudoisochromatic plates using previously described methods. 28 Those who made two or more errors on red-green (RG) screening plates on the second sitting were tested with the RG diagnostic plates and classified to have mild, medium, or strong RG deficiency depending on errors made on these plates. Those who made one or more errors on the yellow-blue (YB) screening plates on the second sitting were classified as mild, and if errors were made on the YB diagnostic plates, they were classified to have medium or strong YB deficiency depending on errors made on these plates.…”

“… 51 DNA was also used in the PCR to amplify exons 2 through 5 of the L and M opsin genes separately, and exons 2, 3, and 4 were directly sequenced. 28 To identify/confirm the genetic cause of aniridia for each participant, the PAX6 gene was amplified and sequenced using PCR primers and conditions that were described previously. 52 Fluorescent DNA sequencing was performed on both DNA strands.…”

The relationship between perifoveal achromatic, L- and M-cone acuity and retinal structure as assessed with multimodal high resolution imaging

“…The L and M pigment genes are located on the X chromosome. Only men, who have a single X chromosome, were included in this study to avoid the confounding effects of polymorphisms commonly found in females (Dees, Gilson, Neitz, & Baraas, 2015).…”