To determine the distribution of iris color and its relationship with some ocular diseases in rural population of Iran.

Two rural areas of North and South West were selected by a cross-sectional study using multi-stage cluster sampling. eye examination including measuring visibility, fraction and Pentacam imaging and then eye examination for patients was performed by Slit-lamp.

Of 3851, 3314 people participated in this study (participation rate, 88.57%). Dark brown (%41.28. CI 95%= 31.88 – 50.68) and blue (%0.99, CI 95%=0.57 – 1.41). Compared to other, people with dark iris have biggest ACD, Angle and Volume while CCT, Keratometry and pupil were highest among people with dark brown iris (p <0.002). Considering brown-dark group as a base group, the chance of being afflicted to cataract among dark-, light-brown-, green- and blue-iris people is 1.89 (CI 95% = 1.25 - 2.86), 1.53 (CI 95% = 1.17 - 2.01), 4.60 (CI 95% = 2.17 - 9.71) and 12.17 (CI 95% = 5.05 - 29.31). The odd ratio of being afflicted to corneal opacity in people with blue iris color was 33.02 (CI 95% = 20.68 - 52.70). The chance of being afflicted with astigmatism among light-brown-, green- and blue-iris color was 1.31 (CI 95% = 1.03 - 1.67), 2.29 (CI 95% = 1.44 - 3.64) and 4.76 (CI 95% = 1.44 - 15.70) respectively. The chance of being afflicted to myopia among green-iris people and to hyperopia among blue-iris people were high (1.60, CI 95%= 1.08-2.36 and 3.20, CI 95%= 1.03 – 9.97 respectively).

Dark brown was the most prevalent iris color in rural areas of Iran. The index of cornea among people with dark- and brown-dark-iris color is higher than others and people with light iris color are at a higher risk of developing eye disease such as cataract, corneal opacity and refractive error.