Abstract
Purpose: :
In the real world, although human visual system mostly deals with chromatic color information rather than achromatic one, conventional subjective tests that measure visual function (e.g., visual acuity test and contrast sensitivity test) still use achromatic color information. For this reason, we developed a prototype of visual function testing device that uses colored Landolt Ring and background that has the capability of testing the color element of vision. This equipment can control the Landolt ring colors, directions of the break, their sizes, time duration of displays, and background colors to any desired values on the dedicated liquid crystal display (ColorEdge CG241W: Nanao Co). Prior to our studies showed that the display screen of this equipment had capabilities of good color repeatability and accuracy (The calculated color difference values (dE) of target and the actual measurements were leveled as"slight"in evaluation criteria based on NBS (National Bureau of Standards, USA). In this work, we evaluated actual aging changes (from the ages 20s to the 80s) in normal eyes using this equipment and reported outcomes based on the different age groups.
Methods: :
One hundred sixty five normal eyes of 165 subjects (100 male, 65 female) were enrolled in this study. The mean age was 44 years old (range 20-84 years). They had no history of ocular disease (including color anomaly) or surgery. All of them had best-corrected visual acuity (BCVA) 20/20 or better. We set the background color as white point of the standard light D65, and Landolt ring was colored with fifteen colors using the New Color Test (Luneau Ophtalmologie). The luminance of background and Landolt Ring is both set approximately at the same value of 30 [cd/m2]. We measured all CVA (Color Visual Acuity; BCVA using colored Landolt Ring) of fifteen different colors for each subjects.
Results: :
Mean CVA (red, yellow red, blue green, blue, red purple and purple red) in 50s group begins to decrease significantly compared with 20s group (P<0.05). Blue purple showed no significant difference compared with all ages. In average 15 colors CVA, 50s, 60s, 70s and 80s group showed significantly worse than 20s (P<0.05).
Conclusions: :
The influence on CVA by aging was different with colors. It was found that CVA begins to decrease from 50s even in eyes with best-corrected visual acuity 20/20 or better.
Keywords: color vision • visual acuity • aging: visual performance