Age‐corrected monocular limits of normal trichromacy

Abstract

AbstractPurpose Chromatic sensitivity worsens gradually with increasing age, but the inherent variability in normal colour vision makes this difficult to detect and to separate from very early changes caused by either retinal or systemic diseases. In this study we developed new approaches to identify and screen for changes that cannot be attributed to normal aging. This approach made it possible to produce reliable, age‐corrected limits for normal colour vision.Methods Red‐green (RG) and yellow‐blue (YB) thresholds were measured monocularly in each eye (using the Colour Assessment and Diagnosis (CAD) test) in 394 subjects (age range: 16 to 90 years). Only clinically normal subjects according to medical history and eye / fundus examination were included. All subjects with congenital colour deficiency were excluded. A new filter based on right / left eye asymmetry for RG and YB thresholds was also employed to exclude subjects with significant differences in monocular thresholds. After filtering, the analysis of the effects of normal aging was based on 178 subjects (age range: 16‐79 years).Results The effects of age (in the range 20 to 80 yrs) can be accounted for well by a linear trend with just over two‐fold increase in both RG and YB mean colour thresholds. Statistical limits of variability (±2σ) were computed from the normal subject data in order to provide limits of age‐corrected RG and YB colour vision.Conclusion The age‐corrected CAD thresholds limits established in this study provide a more accurate way of detecting monocular changes in colour vision caused by either retinal diseases or systemic conditions that affect the eye.