Exercise and the eye in brief
Exercise helps prevent many eye conditions, and the Royal College of Ophthalmologists supports Government recommendations that we take at least 30 minutes exercise a day to protect our sight. Those of us with very sedentary jobs probably need more still, and generally 90 minutes a day is advisable. Children need at least 2 hours a day. Any exercise will help, such as walking, swimming, cycling, gardening, housework, & washing up. Cycling is best commuting BMJ17 BMJ 17
BMJ 16: "Although people with a higher BMI can have lower risk of premature mortality if they also have at least one low risk lifestyle factor, the lowest risk of premature mortality is in people in the 18.5-22.4 BMI range with high score on the alternate healthy eating index, high level of physical activity, moderate alcohol drinking, and who do not smoke. It is important to consider diet and lifestyle factors in the evaluation of the association between BMI and mortality".
Overall lack of exercise probably causes about a quarter of heart and brain disease as we get older, and so exercise is likely to be very helpful for our sight.
Exercise helps prevent diabetes, diabetic retinopathy, macular degeneration, helps glaucoma patients, and will help prevent other conditions such as blocked retinal arteries and veins and cataracts.
Below are some examples as to how exercise will help prevent eye disease.
In this condition the retina, the film at the back of the eye, becomes damaged by the high sugar levels. The retina starts to leak fluid, and also extra-weak blood vessels grow. Together these damage the retina and sight is reduced.
In diabetes we do not have enough insulin. When we are short of insulin we develop high blood-sugar levels, and the high sugar levels then damage all parts of the body, especially our eyes.
Often a diet or drugs are sufficient to make the most of the body's remaining insulin. However, many people with diabetes need extra insulin which they have to inject.
Exercise helps by making insulin last longer. If the diabetes is diet or tablet controlled, exercise will make the most of the remaining insulin. If insulin is injected, it will therefore last longer and so lower doses will be needed. In this way the diabetes will be easier to control and the eye will not be damaged as much.
We now know exercise can prevent type 2 diabetes in the first place as it helps to reduce the insulin the body needs. Some people who develop diabetes could not have done anything to avoid it, but regular exercise has been show to make type 2 diabetes much less likely.
The macula is the centre of the retina..it is very important for seeing faces, television, driving, and reading. As we get older it can become damaged, and we lose our central vision. Side vision stays normal, but without our central vision life can be a struggle. Macular degeneration (ARMD) is common as we get older, but we now know how to prevent some of the damage.
Macular degeneration is worse in patients with high blood pressure and high fat levels in blood. As exercise lowers blood pressure and fat levels it is likely to prevent many cases of macular degeneration.
Retinal artery and vein blockages
The tiny blood vessels in the retina bring the nutrients into the eye, and take the waste products out. These blood vessels are part of the 'cardiovascular' system, and will be damaged in a similar way to arteries in our heart and brain. In the eye this may result in blockages of the retina or optic nerve veins or arteries.Thus high blood pressure, high cholesterol, and high sugar levels, and a diet without many vegetables and fruit, will be harmful.
Exercise is know to be very important in keeping the heart blood vessels healthy, and is very likely to help the retinal and optic nerve blood vessels. The likely result is fewer people with both retinal vein occlusions and retinal arteriole occlusions, both of which can cause severe loss of sight.
Glaucoma is a condition in which the optic nerve becomes damaged by pressure inside the eye (animation). The optic nerve is the 'electric wire' which takes the messages about what we see back to the brain, so if it is damaged our sight is reduced.
The very tiny blood vessels in the optic nerve are very sensitive to pressure in the eye.
Exercise lowers the pressure a little in the eye, and this will improve blood flow to the optic nerve . Exercise is therefore likely to reduce sight loss from glaucoma. Although the effect is not great, it may add about 10% to the effect of eye drops.
Cataracts are also more common in people with high blood pressure and diabetes, so exercise would be expected to help prevent cataracts.