A new study spanning nearly 2 decades has found a link between an unhealthful diet and vision loss in older age. Should we be keeping more of an eye on what we eat?
A robust body of research has shown that a diet rich in red meat, fried foods, high fat dairy, processed meats, and refined grains is bad for the heart and linked to the development of cancer.
However, not many people consider the impact of diet on their eyesight.
A new study, now appearing in the British Journal of Ophthalmology, has found a link between a diet rich in unhealthful foods and age-related macular degeneration (AMD).
AMD is a condition that impacts the retina with age, blurring central vision. Central vision helps people see objects clearly and perform everyday activities such as reading and driving.
According to the Centers for Disease Control and Prevention (CDC), in the United States, around 1.8 million people aged 40 and above are living with AMD, and another 7.3 million have a condition called drusen, which usually precedes AMD.
The CDC also explains that "AMD is the leading cause of permanent impairment of reading and fine or close-up vision among people aged 65 years and older."
Now, the new study — which was the first to look at dietary patterns and the development of AMD over time — has found an association between an unhealthful diet and AMD.
Senior study author Dr. Amy Millen, of the University at Buffalo in New York, told Medical News Today, "Most people understand that diet influences cardiovascular disease risk and risk [of] obesity; however I'm not sure the public thinks about whether or not diet influences one's risk [of] vision loss later in life."
Although research has shown links between certain foods and nutrients and AMD — for example, some studies have suggested that high dose antioxidants may slow progression — there has been less research into dietary patterns as a whole.
Furthermore, studies that have looked at dietary patterns have focused on late-stage risk — that is, the point at which the condition becomes vision-threatening — rather than early and late-stage disease.
"We wanted to examine how the overall pattern of one's diet may predict later development of AMD, both early-onset and late-stage disease," said Dr. Millen.
The study looked at the development of early and late AMD in participants of the Atherosclerosis Risk in Communities study, which looked at arterial health over 18 years (1987–1995).
Using data on 66 different food types, the researchers identified two diet patterns: one they dubbed "Prudent," or healthful, and one they dubbed "Western," which included a high intake of "processed and red meat, fried food, dessert, eggs, refined grains, high-fat dairy, and sugar-sweetened beverages."
Although the researchers found no link between early AMD and dietary patterns, they found that the incidence of late AMD was three times higher among those with a Western eating pattern.
"What we observed in this study was that people who had no AMD or early AMD at the start of our study, and reported frequently consuming [unhealthful] foods, were more likely to develop vision-threatening, late-stage disease approximately 18 years later," says Dr. Millen.
Early-stage AMD has no symptoms, so a person may not know that they have it. Also, although not everyone develops late-stage AMD, for those who do, it can be costly and invasive to treat.
There are two forms of late-stage AMD. One is called wet AMD, or neovascular AMD, which healthcare professionals tend to treat by injecting antivascular growth factors.
The other is called dry AMD, or geographic atrophy, which occurs when the photoreceptor cells die without neovascularization. There is no effective treatment for this form of AMD.
"We would like the public to realize that diet is important to their vision," said Millen.