Shift of Colorimetric Values in Ishihara Pseudoisochromatic Plates with Plate Aging

Purpose: This study aimed to quantify the shift of colorimetric values in the Ishihara pseudoisochromatic test with aging of the plates. Methods: Three sets of Ishihara pseudoisochromatic plates with different published dates (printed in 1971, 1983 and 2001) were tested. Positions matching 32 dots with 13 colors were chosen from each set and the colorimetric values with the CIELAB and HSB/HLS color systems were measured with a spectrophotometer. Lightness (L*), red-green (a*), blue-yellow (b*), chroma, red hue, yellow hue, and green hue values from each set were compared. Results: L* and chroma values were significantly higher in the older versions. The a* values shifted to red (increased a*) and the b* values shifted to yellow (increased b*) with plate aging. Conclusions: Our results showed that the pseudoisochromatic plates had significant changes in color values and a directional shift with aging. Korean Journal of Ophthalmology 19(2):145-148, 2005