Higher exposure to ultraviolet radiation (UV‐R) is associated with greater prevalence of eye disease such as cataracts. We hypothesize that the variation in the intensity of UV‐R can help explain the differences in institutional quality observed across countries. The long‐term incentive and ability to improve the quality of institutions decline when the probability of blindness increases. Our reduced‐form cross‐country results support this hypothesis. We then propose that the mechanism works from the impact of UV‐R on the prevalence of eye disease, which in turn shapes institutions. Our empirical evidence lends considerable support to this hypothesis.