The effect of gender and iris color on the dark-adapted pupil diameter.

PURPOSE

The aims of this study were to assess the utility of digital color sensing to quantify iris color using digital photographs and to determine whether gender or iris color affects the dark-adapted pupil diameter (DAPD).

METHODS

Subjects aged 18-80 years (N = 263) with no eye disease had their right DAPD measured after 2 min of dark adaptation at 1 lux using the NeurOptics pupillometer. A high-resolution digital slit lamp photograph of the iris was taken, and iris color was subjectively classified as blue, blue-green, green-brown, light brown, or dark brown. The digital photographs were objectively measured on-screen with the Minolta TV Color Analyzer II using the Commission Internationale de l'Eclairage system of color description. Regression analyses were performed to identify correlations between subjective iris color, Commission Internationale de l'Eclairage measurements, and DAPD.

RESULTS

Gender and iris color had no effect on the DAPD. The Minolta TV Color Analyzer could discriminate all blue eyes (blue and blue-green) from all brown eyes (light and dark) but could not distinguish between shades of blue or shades of brown. Green-brown irises had no unique chromatic properties and could not be distinguished from other colors using our technique of digital color analysis. The Minolta device was simple and efficient to use.

CONCLUSIONS

Contrary to long-held beliefs, female patients and blue-eyed patients do not have larger DAPD. Digital color sensing is a useful technique for objectively describing iris color.