In a large prospective study of physicians followed over 14 years, Schaumberg et al. found that greater adult height and a pattern of abdominal adiposity were each independent risk factors for cataract in men.
Cataract is the leading cause of blindness worldwide with an incidence of 20% of persons aged 65-74 and 50% of persons aged >75 .
After adjustment for age, lifestyle and other factors, men with the highest waist-to-hip ratios ( WHR ) were 1.55 times more likely to develop cataract as those with the lowest WHR.
The tallest men in the study ( at least 184 cm, or 6 feet and taller ) were 1.23 times more likely to develop cataract than shorter men, and 1.5 times more likely to undergo cataract surgery.
The 17 150 participants were a subset of the larger Physician's Health Study.
They were all healthy male U.S. physicians aged 40-84 in 1982 who completed mailed questionnaires every 6 months during the first year of the study, and then annually for an average of 14 years of follow-up.
Nine years into the study, the physicians were mailed a tape measure with instructions on self-reported waist and hip circumferences ( WHR ) to the nearest quarter of an inch.
All of the subjects were grouped into quintiles based on the distribution of their body mass index ( BMI ), height, and WHR. Incidents of cataract and cataract surgery were self-reported and then confirmed with medical records. Even when adjusting for as many as eight potentially confounding variables, higher BMI, greater height, and higher WHR were consistently associated with a greater relative risk of cataract.
The authors suggest a possible genetic susceptibility in the case of height. WHR, which was consistently associa ted with higher risk of cataract in the study, is a valid measure of abdominal fat, and abdominal adiposity is also a strong risk factor for glucose intolerance and insulin resistance, which are related to risk of type 2 diabetes and high blood pressure.
Diabetes causes earlier cataract formation, and thus several pathways are suggested to account for the relationship between abdominal fat deposition and development of cataracts.
Taylor and Moeller provide an accompanying editorial which asks whether a cascade of disorders such as hypertension, type 2 diabetes, cardiovascular disease and perhaps cataract share a common etiology originating in abdominal adiposity and visceral fat.
The unique metabolic characteristics of intraabdominal adipose tissue may promote cataract formation through elevation of fatty acid concentrations, eventually leading to diabetic-type modifications to lens proteins, a hypothesis which is testable through further research.
Source: American Journal of Clinical Nutrition, 2005