Two Israeli ophthalmologists have another good reason for people to keep their weight under control. Overeaters may not only lack the desire to see what they look like in the mirror; eventually, they might not be able to see themselves.
The ophthalmologists have shown that being overweight – in addition to the known numerous health risks such as heart disease and cancer – also greatly increases your chances of losing your vision.
Following a review of than 20 research studies on thousands of patients around the world, Prof. Michael Belkin and Dr. Zohar Habot-Wilner of the Goldschleger Eye Institute at the Sheba Medical Center found a consistently strong correlation between obesity and the occurrence and development of all four of the major eye diseases that cause blindness – age-related macular degeneration, cataracts, glaucoma, and diabetic retinopathy. Their report appeared recently in the Israeli medical journal Refuah.
"The purpose behind this review was to acquaint physicians and laypeople with the dangers of being fat as related to ophthalmology," explained Belkin, a professor of ophthalmology at Tel Aviv University. "All of this existing research had never been pulled together in a comprehensive way and condensed."
Belkin, the director of the Goldschleger Eye Institute collaborated on the literature review with Habot-Wilner, who is in her final year of residency at the Institute. The Eye Institute is the largest academic ophthalmic care center in Israel, and its reputation in eye care, research and teaching is so strong that ophthalmologists there regularly treat non-Israeli patients, largely from Palestinian cities and from neighboring Cyprus.
The two physicians decided to conduct the review and examine the serious implications of obesity on eyesight because obesity is not only the most prevalent metabolic disease in developed countries, its prevalence worldwide is increasing rapidly.
‘Overweight’ and ‘obesity’ are both labels for ranges of weight that have been shown to increase the likelihood of diseases and health problems. Approximately 119 million Americans, or 64.5 percent, of adult Americans are either overweight or obese. Estimates of the number of obese American adults rose from 23.7 percent in 2003 to 24.5 percent in 2004.
The studies that Belkin and Habot-Wilner examined were "all very long, extremely long epidemiological studies that covered many years from all parts of the world," Belkin told ISRAEL21c. "While all of these studies have been published, the data that has resulted is not well known and no one has ever brought it together and spelled it out to general physicians and the public."
Though Belkin said he knew he would find linkage between obesity and eye disease, he admits that he "didn’t quite expect" it to be as comprehensive as the survey demonstrated. Habot-Wilner also said the correlation was strong.
"Where the Body Mass Index (BMI) was significantly high – in the range of clinical obesity, there was both an increased risk factor for eye diseases and increased progression of disease – when the patients had the diseases, the deterioration in sight occurred faster," she said.
All of the common eye diseases can affect sight to a greater or lesser extent, and most who suffer from them experience deterioration over time.
– Glaucoma is a group of diseases that can damage the eye’s optic nerve and result in vision loss and blindness.
– Age-related macular degeneration (AMD) is a disease that blurs the sharp, central vision you need for "straight-ahead" activities such as reading, sewing, and driving. AMD affects the macula, the part of the eye that allows you to see fine detail.
– A cataract is a clouding of the lens in the eye that affects vision.
– Diabetic retinopathy is a complication of diabetes and a leading cause of blindness. It occurs when diabetes damages the tiny blood vessels inside the retina, the light-sensitive tissue at the back of the eye.
In some of the cases the reasons for linkage between obesity and these diseases was clear – for example, since glaucoma, diabetes and AMD all affect the vascular system and excess weight is known to create pulmonary problems, the blood vessels in the eye are affected, and sight deteriorates. But when it comes to cataracts, the link is less obvious.
"Nobody has the faintest idea why cataracts are affected since it is a disease of the lens of the eye," said Belkin.
Habot-Wilner noted that it is likely that obese people are more likely to contract gout, a disease in which developing cataracts is more common.
She stressed that in the context of their research, they were not concerned with the issues of why these various diseases occur more often and cause more damage in obese people. Rather than focusing on the reasons, Habot-Wilner and Belkin wanted to raise awareness.
"The message we want to send is that obesity can cause not just cancer and hypertension but also ocular disease. While this is something that most ophthalmologists know, it’s not common knowledge and it should be," she told ISRAEL21c. "It’s the risk factor that no one talks about."
Realistically, however, do the two doctors really think that obese people who aren’t put off by life-threatening risks like cancer and heart disease would be motivated to lose weight because of a threat to their sight?
"Maybe not – and I know that it’s very difficult to lose weight, but people had better know the facts," Belkin said.
While those who battle with their weight will obviously find this news depressing, they can at least comfort themselves with the knowledge that those who have trouble controlling their eating are better off than those who can?t stop smoking.
"The importance of obesity as a factor in eye disease is nothing in comparison with smoking as a factor," said Belkin. "That can’t be emphasized enough."
