Measurement of iris color using computerized image analysis

Purpose. To develop a standardized method for measuring from iris photograp hs, light and dark segments of areas and densities of iris color. Methods. Computerized image analysis was used to measure the iris photograp hs. The reproducibility of this method was studied in 30 normal eyes with t hree different colored irides, green-brown, blue-grey brown and yellow-brow n. Three photographs were taken of each iris with a slit lamp camera at thr ee different exposures at baseline. The photographs were repeated with expo sure providing for the best reproducibility at 6.5 +/- 1.7 months as a firs t followup after baseline and 3.6 +/- 0.8 months following the first follow -up visit. At least one measurement was made for each photograph. Results. The mean percent coefficient of variation (standard deviation of t riplicate measurements/mean x 100) ranged from 1.0 to 4.1% for area and den sity measurements. Furthermore, the range of mean percent differences betwe en baseline and follow-up visits ranged from 1.2 to 6.3%. Conclusion. We have developed a standardized method which appears suitable for measuring changes over time in iris color.