Genotyping Could Improve Standard Assessment for Color Vision Deficiencies

Combining genetic assessment and pseudoisochromatic (PIC) plate tests may be more effective in identifying individuals with color deficiencies than PIC tests alone, according to findings published in Acta Ophthalmologica.

Researchers enrolled 454 healthy individuals with normal visual acuity (age range, 16-29 years, 193 men or boys, logMAR ≤0.00) in the study. They collected saliva samples for genotyping and administered 2 different PIC plate evaluations (Ishihara and Hardy-Rand-Rittler (HRR)) for color deficiency. Investigators performed a genetic analysis to estimate the relative number of OPN1LW and OPN1MW opsin genes on the X-chromosome and to genotype 5 different single nucleotide polymorphisms for color deficiency.

The genetic assessment revealed that 78.6% of participants had normal color vision, defined as 1 L opsin gene followed by 1 or more M opsin genes. Among those with color deficiencies, 54 were deutan suspect, 3 were deuteranomalous, 1 had protanope, and 1 had a deutan promoter mutation. Stratified by gender, all girls and women with color deficiencies were deutan suspect (n=28). Investigators noted that 20 girls and women were deutan carriers and 5 were protan carriers.

PIC tests had sensitivities of 0.40 to 0.50 and specificities of 0.97 to 1.00 for boys and men whether used alone or in conjunction with the other PIC test, compared with a sensitivity and specificity of 0.50 to 1.00 and 0.95 to 1.00, respectively, in the girls and women’s group. 

Combining the genetic and PIC plate assessments categorized 13.2% of boys or men as red-green color deficient compared with 5.2% for the PIC tests alone.

“Combining the Ishihara with [genetic testing] appears to be sufficient for identifying red-green color-deficient males, but not females.” according to the researchers. “Including the HRR in the battery of tests allows for the identification of red-green color-deficient females as well as grading of the deficiency.”

Study limitations include failure to evaluate regulatory regions for opsin genes and reliance on participant self-reporting for family history information.

Reference

Arnegard S, Baraas RC, Neitz J, Hagen LA, Neitz M. Limitation of standard pseudoisochromatic plates in identifying colour vision deficiencies when compared with genetic testing. Acta Ophthalmol. Published online February 3, 2022. doi:10.1111/aos.15103