Risk factors for age-related cortical, nuclear, and posterior subcapsular cataracts. The Italian-American Cataract Study Group.

A total of 1,008 cases and 469 controls, aged 45-79 years, were included in a clinic-based case-control study of age-related cataract in Parma, Italy, from 1987 to 1989. Associations were examined between specific types of cataract and physiologic, behavioral, environmental, and biochemical factors. Cases included subjects with pure cortical (n = 489), pure nuclear (n = 110), pure posterior subcapsular (n = 28), and mixed (n = 381) cataracts. With polychotomous logistic regression, an increased risk of cataract was found for females (cortical; odds ratio (OR) = 2.20) and persons with less than a high school education (all types; OR = 1.53), brown irises (nuclear, mixed; OR = 1.43), job locations in the sunlight (cortical, mixed; OR = 1.75), leisure time activities in the sunlight (cortical, mixed; OR = 1.45), a history of wearing a hat in summertime (posterior subcapsular, cortical, mixed; OR = 1.80), a positive family history of cataract (posterior subcapsular, cortical, mixed; OR = 1.88), a history of cortisone use (posterior subcapsular; OR = 8.39), increased red blood cell glucose-6-phosphate dehydrogenase activity (cortical, nuclear, mixed; OR = 1.36), and increased serum levels of uric acid (posterior subcapsular; OR = 1.62), lactic dehydrogenase (posterior subcapsular; OR = 1.76) and gamma-glutamyl transpeptidase (mixed; OR = 1.22). A decreased risk of cataract was found for persons with a positive history of arthritis (posterior subcapsular, nuclear, mixed; OR = 0.56) and increased handgrip strength (mixed; OR = 0.68). Findings from our study, combined with previously reported evidence, suggest that associations with educational status, cortisone use, sunlight exposure, and handgrip strength are real. Other findings require further evaluation.