How does the eye function?
Vision is created by the collective function of different parts of the eye. Our eyes collect visual information and transmit it to the brain and thereby begin this complex process. The light first passes through the cornea, which is a dome-shaped surface covering the front of the eye. The incoming light is refracted by the cornea. The colored part of the eye, called the iris regulates the size of the pupil, the opening controls the amount of light entering the eye. The lens lies behind the pupil that further focuses image or light onto the retina. The retina is a delicate, photosensitive tissue that contains ‘photoreceptor’ cells converting light into electrical signals. These signals are further processed and transmitted to the brain through the optic nerve, which is a bundle of nearly one million nerve fibers.
Vision problems
Some of the common vision problems are refractive errors like-
- Farsightedness or hyperopia
- Nearsightedness or Myopia
- Presbyopia and
- Astigmatism
Some eye problems involve risk factors, they are-
- Cataract
- Age-related Macular degeneration
- Glaucoma
- Diabetic Retinopathy
Make sure you incorporate the habit of getting eyes tested regularly. Comprehensive dilated eye exam helps in protecting your sight as there are several diseases that have no early warning signs. Many people have vision problems that can lead to vision loss and even blindness, some common problems can be corrected easily with contact lenses or glasses. Early treatment can always prevent eye problems from getting worse. Keeping track of family’s eye health history, wearing protective eyewear, staying stress-free, keeping your hands and contact lenses clean and stop smoking are some of the ways to keep your eyes healthy. But most importantly, including fruits and vegetables in the diet is important for keeping your eyes healthy.
Let’s take a look at few nutrients that are good for the eye health.
Vitamin A
it plays a vital role in vision and may protect against dry eyes and night blindness. Vitamin A helps the surface of the eye to be effective barriers to viruses and bacteria, thereby minimizing the risk of eye infections. Vitamin A from colorful vegetables and fruits are in the form of ‘provitamin A’ carotenoids. They get converted to retinol after the food is ingested. Cantaloupes, kale, spinach, sweet potatoes and carrots are rich sources of provitamin A carotenoids. Whereas, Vitamin A derived from animals are called retinols and can be directly used by the body as they are ‘pre-formed’. Rich source of retinol vitamin A are whole milk, cheese, chicken liver and beef.
Beta-carotene
it is an orange/yellow pigment that imparts fruits and vegetables their rich colors. Beta carotene is an antioxidant and carotenoid and gets converted to Vitamin A which is an essential vitamin. Along with Vitamin C & E and zinc, beta-carotene can minimize the progression of macular degeneration. Foods rich in beta-carotene are sweet potatoes, squash, pumpkin, plums, peppers, peas, onion, kale, grapefruit, chives, carrots, broccoli, asparagus, and herbs and spices like parsley, oregano, paprika.
Vitamin D
it is a fat-soluble vitamin which is quite essential for our eyes as it can bring down the risk of macular degeneration. One of the best ways of Vitamin D is exposure to sunlight. Just a few minutes exposure ensures that the body is producing adequate Vitamin D. Other sources of Vitamin D are orange juice fortified with Vitamin D, milk, mackerel, sardines and salmon.
Vitamin C
it has been observed that those with high intake of Vitamin C had almost 20 percent less chance of developing cataract. It is not always possible to avoid developing cataract, however, consuming food rich in Vitamin C can delay the onset and keep them from worsening significantly. Vitamin C is water soluble and does not get stored in the body, hence must be consumed every day. Some of the foods rich in Vitamin C are tomatoes, spinach, sweet potatoes, papaya, butternut squash, Brussels sprouts, broccoli, red bell peppers and citrus fruits.
Omega-3 Fatty acids
our bodies cannot function properly without fats, therefore the eyes may also suffer. Fatty acids, on the other hand, are building blocks of fat and are critical for the functioning of organs, nerves, muscles and cells. Fatty acids also aid in the production of hormone-like compounds that regulates heart rate, blood pressure and blood clotting. Essential fatty acids should be included in the diet as it cannot be produced by them. Omega-3 fatty acids have alpha-linolenic acid (ALA), eicoapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Omega-3 fatty acids are said to be important for normal infant vision development. It can also help in preventing dry eyes and macular degeneration (AMD). Food sources of omega-3 fatty acids are walnuts, freshly ground flaxseeds, fish oil supplements, salmon, herring and mackerel.
Bioflavonoids (Flavonoids)
it is usually found in the same foods that are good sources of vitamin C. Bioflavonoids are natural pigments that impart color to the vegetables and fruits and are water soluble and nontoxic, even at high doses. It is said to protect against macular degeneration and cataracts. Food sources of flavonoids are soy products, legumes, cherries, blueberries, bilberries, citrus fruits, red wine and tea.
Lutein and Zeaxanthin
these are two carotenoids located in the eye. They bring down the risk of chronic eye diseases like cataracts and age-related macular degeneration, which are the leading causes of visual impairment. Lutein and zeaxanthin help in maintaining healthy cells in the eyes and also filter harmful high –energy blue wavelengths of light. The human body does not make lutein and zeaxanthin naturally, it is therefore essential to include vegetables like squash, collard greens, turnip greens, kale and spinach in the diet.
Selenium
it brings down the risk of advanced age-related macular degeneration when combined with vitamin C and E and carotenoids. Food sources of selenium include enriched noodles, brown rice, Brazil nuts and seafood like halibut, salmon, crab and shrimp.
Zinc
it is one of the important mineral for eye health. It is found in high concentration in the vascular layer of tissue below the retina. Zinc helps in transporting vitamin A from liver to this area, so that melanin is produced. Zinc plays an important role in preventing and reducing age-related macular degeneration and poor night vision. In order to increase the intake of zinc, include pumpkin seeds, hemp seeds, cooked quinoa, legumes, cashews, turkey, Dungeness crab, beef and oysters in your diet.
Daily recommendations for healthy eye
The daily recommended nutrients for healthy eyes that will help you get Recommended Dietary Allowance (RDA) are-
- 2 mg of copper oxide
- 80 mg of zinc oxide
- 2 mg of zeaxanthin
- 10 mg lutein
- 400 international units of vitamin E
- 500 mg of vitamin C