cigarette smoke has been linked to a higher rate of cataract but a new study says that even those who chew tobacco are at risk. Chewing tobacco is common in India, where cataract accounts for 44 per cent of blindness cases. Other risk factors for cataract include exposure to ultraviolet rays, indoor air pollution and malnutrition.
The researchers from Sankar Netralaya, a not-for-profit charitable eye hospital in Chennai, found the link between tobacco and cataract when they analysed data from a glaucoma study that covered 3,924 people from 27 villages in Thiruvallur and Kancheepuram districts of Tamil Nadu. Information was collected on tobacco use, type of tobacco (smoking or smokeless), period of use and amount used.
The researchers found that 73 per cent of people who used smokeless tobacco developed cataract. They also found that smokeless tobacco brings about up to a three-fold increase in the blood cadmium -- a mineral.Earlier studies have shown that high levels of cadmium can inactivate the enzyme superoxide dismutase that protects the body from oxidative damage.
But the study has major limitations, the authors accept. For one, the research was not specifically designed to study risk factors for cataract and data collection was not done keeping it in mind. Data regarding nutritional status, exposure to sunlight, exposure to indoor smoke and other factors that could affect the results were not collected. The study appeared on July 12 in the online version of the British Journal of Ophthalmology.
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