Kilos could dim your sight

How much you weigh and whether you exercise could influence more than just your jean size.

It might also have a powerful impact on the progression of age-related macular degeneration, a disease affecting some thousands of South Africans and a major cause of blindness among seniors, reports a study in the June issue of the Archives of Ophthalmology.

Why research is unique and important
What makes this research unique is that it involved evaluation of the progression of this disease, and a documentation that certain factors – most notably body mass index and exercise – can play a role in how quickly that progression occurs, says study author Dr Johanna Seddon, of the Massachusetts Eye and Ear Infirmary.

The idea that these factors could be modified and controlled makes the finding that much more meaningful and important to patients, Seddon adds.

Age-related macular degeneration (AMD) develops when the high concentration of light-sensing cells in the central portion of the retina – the area known as the macula – malfunction or begin to lose function. Initially, this causes a decrease in central vision and the inability to see fine detail. Eventually, it destroys sight, plunging some 40 000 South African seniors into total blindness each year.

Different theories to explain correlation
While doctors aren’t certain why weight and exercise make a difference, Seddon believes it may influence inflammation in the tiny blood vessels that remove waste products from the retina.

Right now we know that some of the same risk factors for heart disease – smoking, obesity and lack of exercise – also affect the progression of AMD, Seddon says.

For ophthalmologist Dr Robert Cykiert, the study is an important step forward for patients with this devastating disease.

Because AMD has no known cure, slowing down the progression is the only tool that patients have to preserve their eyesight. So, obviously, anything that can help accomplish this is vital, says Cykiert, a clinical associate professor of ophthalmology at New York University Medical Center.

While he says it’s important that the finding is verified by larger studies, he adds this: I would tell any overweight patients at risk for AMD, or with AMD, that it’s probably a good idea to lose some weight, particularly since obesity is associated with so many other diseases.

The research study
The new study involved 102 men and 159 women, aged 60 or older, diagnosed with signs of non-advanced AMD.

Patient interviews documented risk factors, including smoking and alcohol consumption, while a dietary questionnaire detailed total daily intake of calories, carotenoids such as beta carotene and alcohol. Also considered was previous history of cardiovascular disease, cancer, or diabetes, and any regularly used medication.

Height, weight, and blood pressure measurements were taken, and each patient had a thorough eye examination. These tests, along with the food questionnaire, were repeated annually. Patients also self-reported waist and hip measurements, along with documenting physical activity and regular exercise regimes, throughout the study period. The average follow-up time for each patient was 4,6 years, with some followed for as long as seven years.

Progression nearly twice as fast
The result: Patients with a high body mass index (25 to 29, which constitutes overweight, and 30 or more, which is considered obese) experienced the fastest AMD disease progression – nearly twice as fast as those with a lower body mass index.

Moreover, those with a higher waist circumference – indicating a greater amount of weight in the midsection – saw a twofold increased risk for the progression of AMD.

On a more positive note, those who participated in regular exercise saw a reduction in disease progression – up to 25 percent for those who engaged in vigorous activity three times a week or more. This, says Seddon, was independent of any weight loss.

The next step, say researchers, is to discover if losing weight can reverse the path of the disease.


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