A prospective study of the relationship between body mass index and cataract extraction among US women and men

Obesity may influence several physiologic processes involved in cataract formation such as oxidative stress, glycosylation and osmotic stress.

To examine the association between increased body mass index (BMI) and the incidence of cataract extraction.

The Nurses' Health Study and the Health Professionals Follow-up Study, both prospective cohort studies of US women and men.

A total of 87 682 women and 45 549 men aged 45 y and older who did not have diagnosed cataract or cancer at baseline (1980 for women, 1986 for men).

Cataract extractions occurring between baseline and 1996, confirmed by medical records.

During 16 y of follow-up in the women, and 10 y in the men, (1 097 997 person-y), 4430 incident cases were documented. Compared to participants with BMI less than 23 kg/m(2), those with BMI greater than or equal to 30 kg/m(2) had 36% higher risk of any type of cataract (pooled multivariate relative risk (RR), 1.36; 95% CI, 1.23-1.49) after adjusting for smoking, age and lutein/zeaxanthin intake. The association was strongest for posterior subcapsular (PSC) cataract (pooled multivariate RR, 1.99; 95% CI, 1.55-2.55). With adjustment for diabetes, the RR of obesity associated with posterior subcapsular cataract was 1.68 (95% CI, 1.30-2.17). Obesity was not significantly associated with nuclear cataract.

Obesity increases the risk of developing cataract overall, and of PSC cataract in particular; the etiology of PSC cataract may be mediated at least in part by glucose intolerance and insulin resistance, even in the absence of clinical diabetes.