Environmental factors in the epidemiology of malignant myopia.

Malignant myopia is a major cause of blindness, yet compared with cataract, glaucoma, or diabetic retinopathy, this condition has received little attention from clinical investigators. This study explores existing health and geophysical records in search of clues that might suggest directions for further research into the etiology of blinding myopia. From the environmental data available for analysis, annual hours of sunshine emerged as the factor with the strongest (inverse) association with malignant myopia. Using data from the 14-state Model Reporting Area for Blindness, a case-referent study of this factor revealed both sex and age-birth year modifications of this effect. Relatively more blindness due to malignant myopia occurred among women in low sunshine regions and among men in high sunshine regions. The effect among women appeared during middle age (45 +, or born before 1926) but among men was not seen until later (age 65 + or born before 1906).