Macular degeneration is a medical condition in which a person or animal progressively loses sight in one or both eyes. The degeneration is usually slow, and begins at the center field of vision; over time, usually months or years, the problem grows. Sight progressively becomes more and more limited, and while it’s rare for full blindness to result, vision is almost always significantly impaired. Age is the most common cause of the condition, but other risk factors, including smoking and family history, can also contribute. Once diagnosed the condition isn’t usually curable, though there are things patients can do to try to slow the disease’s progress and make use of the sight they have left.
The condition is caused by the degeneration of the macula, which is a small, opaque spot in the center of human and many animal eyes. The macula is also referred to as the eye’s "yellow spot." These tiny yellow areas near the center of the retina are the place where visual perception is most acute.
Macular degeneration causes the destruction of these photo-receptors and creates a lack of pigment in the eyes. Reduced pigmentation is believed to be a risk factor in the development of the disease, and people with light colored eyes — blue and green particularly — are often seen as more at risk generally.
In most cases the degeneration is painless and usually starts very slowly, and as a result people can be unaware that they are impacted until they actually start losing their sight. Sight loss is usually progressive, and starts as basic blurring; some people also experience “white spots,” where vision is more or less blank. Wavy and blurry lines running across the center field of vision are common, too. Over time people usually find that they can see less and less, sometimes described as looking through a tube or a straw, and things often don’t look as bright or sharp as they used to.
Age is the most common cause, with the vast majority of those affected over the age of 50. Medical experts don’t necessarily consider it a normal part of aging, but it isn’t usually a surprising consequence either, particularly for people who have experienced eye weakness or vision troubles in their youth.
Other possible causes include a low dietary intake of certain nutrients, particularly omega-3 fatty acids and folic acid; regular exposure to tobacco smoke; and excessive exposure to bright sunlight, usually spanning several years. Things like race, gender, and family history also play a role. Women are more likely than men to develop this condition, and those of Caucasian and East Asian descent are usually more at risk, too. There isn’t a firm genetic link insofar as there’s no inherited gene or trait, but eye issues can sometimes run in families, making the children or siblings of a sufferer more likely to experience the problem themselves.
There is no cure for the condition, and treatment usually focuses on stalling vision loss and preserving whatever is left. Diagnoses vary from person to person and ultimately a plan of care will depend on how advanced the disease is, as well as the specific type of degeneration that’s present.
In most cases there are two types of degeneration: "dry," which represents approximately 90% of cases, and "wet," which represents the remaining cases. "Dry" macular degeneration is particularly difficult to treat primarily because it is not treatable with surgery and can eventually develop into the "wet" type.
"Wet" macular degeneration refers to the overgrowth of small veins under the macula, which then leak fluid. Laser surgery can halt the condition in many cases, though it is possible that this surgery will actually create a blind spot in the middle of the macula. The benefits achieved with surgery are not usually permanent, either. They can buy sufferers a little bit of time, but eventually, venal re-growth is likely to recur and fluid will probably leak into the macula again in the future.
There isn’t usually much that people can do to reverse the disease once it’s set it. Sometimes small lifestyle changes can reduce a person’s chance of developing it in the first place, though. Wearing sunglasses when outside, refraining from smoking, and consciously choosing a diet high in antioxidants are common recommendations.
In particular, diets high in the nutrient zeaxanthin are frequently praised. Zeaxanthin is an antioxidant compound that occurs naturally in the body, as well as in many plant products. It protects the sensitive cells of the eye from harmful blue-light waves in much the same way that sunglasses do. Studies have shown that portions of the macula with the highest concentration of zeaxanthin are the last to degenerate. Levels of zeaxanthin decline with age and age-related zeaxanthin loss is suspected as a factor in both types of this disorder.
Zeaxanthin is produced by the conversion of lutein in the eye. In addition, both zeaxanthin and lutein are carotenoids, also know as “yellow pigments,” that are found in high concentrations in yellow fruits and vegetables, as well as in dark green leafy vegetables like spinach, collard, and kale. Carotenoids are absorbed into the blood and deposited preferentially in the eye tissues, where they protect against free radicals and absorb harmful blue-light rays. Eating diets rich in these sorts of foods is often one of the best ways for people to reduce their chances of developing the degeneration, or at least stall its progress if it’s already been diagnosed.