About the eye

Our eyes work by allowing a light wave from an object to enter via the pupil (circular opening in the centre of the iris). The pupil, which appears black because most of the light entering it is absorbed by the tissues inside the eye, controls the amount of light that enters the eye, narrowing and widening to accommodate the required light response for optimum vision.

Bent light waves pass through the lens (a transparent structure) of the eye and along with the cornea, helps refracted light to be focused on the retina (a light sensitive tissue lining the inner surface of the eye). The retina registers tiny impulses and turns them into electrical signals. These signals are sent via the optic nerve to the visual processing part of the brain known as the occipital cortex. It is here that the electrical signals are interpreted as a visual image - and this is known as seeing.

Maintaining healthy eyes

A good, well-balanced diet which includes a mix of fats, protein, carbohydrates, vitamins and minerals is essential to remain healthy. Certain vitamins, minerals and essential fatty acids, such as omega-3 fatty acids, are vital for eye health.

A group of nutrients called carotenoids (found in coloured foods such as carrots, peppers) and vitamin E, which act as antioxidants, are particularly important and work by helping protect the retina from oxidative damage caused by excess free radicals which are often generated by light absorption.

Although the generation of free radicals is a necessary and normal process, many environmental, lifestyle and pathological factors can result in excess free radicals, causing an accumulation of damaged biological molecules in the cells, known as oxidative stress. ¹

During this process, damage to fats, proteins, carbohydrates and nucleic acids (molecules that carry genetic information or form structures within cells) may occur. The retina is particularly susceptible to this oxidative stress because of its high use of oxygen, its high proportion of polyunsaturated fatty acids, and its exposure to visible light.

The retina has the highest concentration of docosahexaenoic acid (DHA) and carotenoids such as lutein and zeaxanthin. It is essential to have these in your diet as the body can not synthesize them. Lutein acts as a scavenger of free radicals and also acts as a filter of blue light, helping to protect the membranes on the outside of the retina which are rich in polyunsaturated fatty acid. ²

There are three major types of omega-3 polyunsaturated fatty acids which the body needs: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Once eaten, the body converts ALA to EPA and DHA, which are the two types of omega-3 fatty acids more readily used by the body.

With today's busy lifestyles, special dietary requirements and intolerances, it can sometimes be difficult to ensure you are getting the right balance of nutrients. Specially formulated food supplements provide a useful means of helping safeguard dietary intake and hence may help in maintaining healthy eyes.

1. Willcox, J et al. Antioxidants and prevention of chronic disease. Critical Reviews in Food Science and Nutrition. 2004;44 275-295
2. lves-Rodrigues A, Shao A. The science behind lutein. Toxicol Lett. 2004;150(1):57-8