Evangelos 5. Gragoudas, * and the Eye Disorders Case-Control Study Group

A system for classification of iris color based on standard photographs, developed for use in a multiccntcr study, is described. Categories of iris color are distinguished based on predominant color (blue, gray, green, light brown, or brown) and the amount of brown or yellow pigment present in the iris. Two trained readers independently graded 339 iris photographs; discrepancies in grades were adjudicated. Measures of interobserver reliability were 0.76 by kappa for exact agreement and 0.97 for weighted kappa. The distribution of iris color grades demonstrates that the system achieved an appropriate level of detail within the authors " study population, which included patients with various racial backgrounds from five urban clinical centers. This simple, reliable classification system for iris color is offered for use in clinical research. Invest Ophthalmol Vis Sci 31:1592-1598, 1990 A growing number of epidemiologic studies in-clude grading of iris color. Interest in such grading has been stimulated by reports of association between iris color and several ophthalmic diseases, including ocular melanoma12 and age-related macular degen-eration.14 In the past the gradings have depended o