Iris pigmentation has several physiologic functions, including protection of the underlying tissues from ultraviolet radiation and a protective role in various diseases, such as age-related macular degeneration, cataract and uveal melanoma. Uveal melanoma has been reported to be more prevalent among white people with light irides. It has been suggested that the increased risk may be due to the lack of pigmentation, which allows greater light transmission to the uvea. In this article the author reviews the association between iris colour and ocular disease, particularly uveal melanoma.