The macula is a small area located near the centre of the retina at the back of the eye. The macula contains a naturally occurring protective substance called the macular pigment, which is made of three carotenoid pigments, lutein, zeaxanthin and meso-zeaxanthin. These help to protect the eye tissue from photodamage, enhance retinal membrane stability, provide antioxidant protection and optimise visual function. Lutein and zeaxanthin are also the carotenoids found in the lens, having a protective effect on the lens of the eye, reducing the risk and severity of cataracts.
Macular degeneration begins with the formation of drusen, which are deposits of accumulated metabolic waste products. There are both genetic and environmental risk factors including oxidative stress, chronic inflammation, smoking, aging, cardiovascular risk factors and low antioxidant intake. The eye is particularly susceptible to the effects of oxidative stress due to its high consumptions of oxygen, high content of polyunsaturated fatty acids and exposure to visible light. Oxidation of the polyunsaturated fatty acids in the eye is thought to be a major contributing factor to macular degeneration.
Certainly the leading nutrients that have been shown in studies to reduce macular damage and vision loss in patients with early age-related macular degeneration, are the carotenoids lutein and zeaxanthin. It has also been found that lutein can help protect the retinal nerves from damage during periods of inflammation. Zeaxanthin and Lutein-rich foods include dark green leafy vegetables such as kale, collard greens, turnip greens, romaine lettuce and spinach, and smaller amounts are in eggs, corn, broccoli, brussels sprouts and green beans.
In exploring retinal detachment, it has been shown that oxidative stress is a prominent feature of eyes with primary retinal detachment, therefore an antioxidant supplement is highly recommended for people at risk of this condition. Antioxidants of course are beneficial to help prevent a wide range of diseases, and one containing lutein or zeaxanthin would be an excellent combination.
Another antioxidant, resveratrol, has been shown in studies to help protect against photoreceptor cell death in retinal detachment. This may then help to prevent vision loss in retinal detachment.
Bilberry is a traditionally used eye tonic that helps relieve eye-strain and visual fatigue by supporting ophthalmic microcirculation and strengthening the integrity of the capillary walls. Bilberry may help regenerate rhodopsin, a photosensitive protein in the retina responsible for vision in low light, thus the stories of fighter pilots in the war eating lots of bilberry (blueberry) jam to help their night vision.
Other nutrients essential for eye health that have also been shown to be beneficial in helping prevent macular degeneration include vitamins A, C and E, zinc and fish oil.
An assistant professor at Tufts University School of Medicine, Boston, has explained that the quick rise in blood sugar levels caused by high glycaemic index foods (sugar and refined carbohydrates) may lead to gradual damage of the macula. High GI foods lead to excess blood sugar, which increases oxidative stress and can lead to cellular damage.