Analyses examine association between risk factors, cataracts

October 1, 2009

Results of a large epidemiologic study show a number of factors that seem to be associated with a higher risk of cataract.

San Francisco-Results of a large epidemiologic study including 40,000 patients show a number of factors that seem to be associated with a higher risk of cataract.

The investigation was conducted by Chattadi Srinivas, MD, and colleagues and reviewed data on age, gender, region of residence, diet, nutrition, occupation, and lifestyle factors for this large group of patients in India with senile cataracts. The analyses, presented at the annual meeting of the American Society of Cataract and Refractive Surgery, showed that, among other factors, older age and living in rural versus urban areas and in northern India versus the south were associated with a higher incidence of cataract.

"Cataract is a multifactorial idiopathic ocular disease that is a major cause of blindness in the world," said Dr. Srinivas, chief medical officer, Pushpagiri Vitreo Retina Institute, Secunderabad, India. "Its precise etiology is still not understood, and while epidemiologic studies may not be able to determine the mechanism of cataract formation, they are helpful for assessing factors that may contribute to lens insult. Such information may help with strategies to reduce the economical, social, and personal problems associated with cataract."

Of the 40,000 cases, 55% were male and 45% were female. Patients ranged from age 40 to 89 years. Data on age distribution showed patients aged 60 to 69 years accounted for 30% of the study population; 42.5% were younger, and 27.5% were aged 70 or more years.

"Other research also shows males are affected more than females, and it may be that estrogen is a factor protecting women from cataract formation," he said.

More patients with cataracts were in rural than urban regions: 52.5% versus 47.5%, respectively. The northern region of India was more represented by the study population than the south: 52.5% versus 47.5%. This representation may reflect cultural, food, habits, and climatic differences between the two regions, Dr. Srinivas said.

Other risk factor data

Data on occupation showed that among the different categories, agricultural professionals accounted for the largest proportion of the study group (30%).

"Likely, excessive ultraviolet light exposure from time spent by farmers in the fields may explain these data," he said.

Poor nutrition appeared to increase the risk of cataract: 45% of the group was considered to have poor nutrition, whereas nutrition was considered moderate in 30% and good in only 25%. A higher proportion of the population also was represented by lower socioeconomic status compared with moderate or high, 40% versus 35% and 25%, respectively.

"Greater health consciousness and healthier lifestyles among people with higher soceioeconomic status may explain the greater representation of people with poorer socioeconomic status," Dr. Srinivas said.

Vegetarians accounted for a lower proportion than non-vegetarians, 47.5% versus 52.5%, respectively. Just more than half of the population (51%) had excessive sugar intake, whereas just less than half (49%) had a spicy diet.

He added that India is somewhat unique among nations in the world in terms of the high proportion of residents who are vegetarians. Dietary differences-including higher intake of foods containing antioxidants and beta-carotene by vegetarians-that may delay or arrest lens opacification may explain the lower prevalence of vegetarians in the study population.

Yoga was practiced by 45% of the population, and perhaps those who practice yoga also might have generally more healthful lifestyles than their non-practicing counterparts, Dr. Srinivas said.

The data also suggested an association between cataracts and both alcohol intake and smoking. Only 25% of the population were nonsmokers, 45% were smokers, and 30% were passively exposed to smoke. Alcohol consumption was reported in 55% of the population.