Benefits of exercise preventing eye disease David Kinshuck |
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| Age-related macular degeneration (ARMD) | Macular degeneration is a condition in which the centre of the retina becomes damaged. As the retina is the 'film' of the camera, if it is damaged. It is much more common as we get older, but smoking, genes, and environmental factors contribute.High blood pressure may be related to macular degeneration (below, Ref), This suggests that lowering blood pressure with exercise is likely to be helpful slowing down the development of (below, Ref). Being overweight was observed to be associated with progression of ARMD (below, Ref). We now know for certain that exercise helps, for instance regular exercise reduces risk of wet macular degeneration by 70% . ARMD affects 30% of people in their nineties, so exercise all through our life is likely to have a significant impact (below, Ref). The macular damage occurs probably due to an increased accumulation of waste products in the retina, although the exact mechanism is unknown (animation here). |
Exercise may also even prevent diabetes in the first place, and if we all exercised the amount of diabetes in a population would be reduced by about 50%. (below, Ref). Exercise works by reducing insulin resistance, so that the insulin our pancreas naturally releases will have a greater effect on our muscles. Exercise makes the insulin let more glucose into muscle cells, and this lowers the body's blood glucose level.25% of people with diabetes have diabetic retinopathy at any one time. With current treatment, most people with diabetic retinopathy do keep good sight, but many are not so lucky (Ref). Exercise will help, particularly in the long term. It helps partly by lowering blood pressure (UKPDS, Ref) , and by improving diabetic control in the centre we will notice poor central vision. This will make it difficult to read or see faces or television. (RNIB, diagram). |
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Glaucoma is a condition in which the optic nerve becomes damaged and vision is reduced. Exercise is likely to help by lowering the pressure on the optic nerve (animation), as indicated below. Fluid is made in the middle chamber of the eye, and then flows through into the front chamber. It then flows out of the eye through a drainage system. This drainage system is called the 'trabecular meshwork', and the fluid is called 'aqueous fluid' see diagram. In glaucoma the drain blocks, so fluid gets trapped in the eye. This then makes the pressure in the eye go up. The high pressure in the front of the eye is transmitted back to the optic nerve. The nerve becomes damaged, like a tyre being pumped up too hard, see & see. The treatment for all types of glaucoma is the same, that is to lower the pressure in the eye (intraocular pressure). The treatment is eye drops, or occasionally surgery or laser (see). Exercise has been proven to lower intraocular pressure here , here here here. We know that lowering intraocular pressure protects
the optic nerve in glaucoma see and see. We know for certain that exercise lowers blood
pressure (Ref);
we know blood pressure is related to intraocular pressure (Ref);
and we know that a low intraocular pressure helps glaucoma (Ref). Very rarely, in young people with advanced glaucoma, exercise may lead to temporarily reduced sight: here expert advice is needed from ophthalmologists (below, Ref). In some types of glaucoma the main problem is thought to be poor blood flow to the optic nerve itself. This is 'normal or low tension glaucoma' (see), and again logic would suggest that it is possible for exercise to help by lowering the intraocular pressure. |
This is a condition in which the lens of the eye becomes
cloudy or opaque (see). Fortunately surgery is very helpful, but it would
be better still if they could be prevented. As we know exercise lowers blood pressure, it is likely to help a little reducing cataract formation. |
Blocked arteries or veins in the retina are serious conditions.
They often cause damage to the retina ('retinal vein or artery occlusion') Once again, as exercise keeps blood pressure lower, it is likely to slightly reduce the incidence both conditions (Ref). |
High blood pressure often plays a role in other eye conditions or by other mechanisms. Certainly, exercise and having a low blood pressure helps prevent heart attacks, strokes, osteoporosis, arthritis, and cancer (Ref, Ref) (below, Ref), Lack of exercise may result in a vicious circle of problems. As mentioned, lack of exercise contributes to obesity, which in turn contributes to arthritis ref. In turn the arthritis may prevent further walking Ref, and this may in turn lead to even higher blood pressure. |
Exercise and risk taking behaviour |
Exercise will help to prevent eye problems in less obvious ways. Those of us who do not exercise are more likely to be involved in risk taking behaviour (below). This is so even in adults (Ref). Risk taking behaviour reduced by exerciseparticularly amongst adolescents, e.g. this might include driving without a seatbelt, and risking a serious perforating eye injury; alternatively it may be having sex without a condom, and risking HIV and the retinal infections that may follow (Ref). |
Indirect effects of alcohol |
Perhaps more importantly risk taking behaviour includes
binge drinking, which in turn leads to assaults. 24 years ago in the But at the same time there has been a dramatic increase in the number of serious eye injuries as a consequence of binge drinking ...yet as above regular exercise reduces binge drinking behaviour (below). Visit any inner-city eye casualty on many Friday and Saturday nights...such injuries occur far too regularly (below, Ref). The eye injury is often suffered by an innocent passer-by. |
NHS Direct recommends 30 minutes a day. This is probably enough if you have a reasonably active job, or walk a little during the day. If you drive to work, and park immediately outside your office, then 30 minutes will not be enough. (NHS Direct). However, this paper suggests at least an hour a day may be best. But the latest advice comes from the US Department of Agriculture, which recommends 90 minutes a day. It may be helpful to wear a pedometer to see how much you are walking: certainly some studies show that many of us are not walking enough (Ref). Most forms of exercise will be just as helpful. Swimming, cycling, gardening, golf, most sports, even cleaning the house will help. |
At present it is difficult to gauge exactly how much exercise contributes, but here are some figures.
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Although exact figures are unknown, lack of exercise contributes significantly to several eye conditions affecting the elderly, with a slightly lower contribution for middle age patients. |
References |
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Exercise and intraocular pressure |
Eur J Ophthalmol. 2004 Mar-Apr;14(2):117-22. |
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J Strength Cond Res. 2003 Nov;17(4):715-20. |
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Optom Vis Sci. 2003 Jun;80(6):460-6. |
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Can cause problems |
Eye. 2001 Oct;15(Pt 5):616-20. |
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Diabetic retinopathy |
Acta Ophthalmol Scand. 2004 Oct;82(5):526-30. |
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UKPDS study |
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Curr Treat Options Neurol. 2004 Nov;6(6):443-450. |
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Exercise, mental health, diabetes |
Diabetes Care. 2004 Sep;27(9):2154-60. |
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J Sci Med Sport. 2004 Apr;7(1 Suppl):6-19. |
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JAMA. 2004 Sep 8;292(10):1179-87. |
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Ann Epidemiol. 2002 Nov;12(8):543-52 |
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Exercise and Blood Pressure |
Eur J Cardiovasc Prev Rehabil. 2004 Jun;11(3):192-200. |
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Am J Ophthalmol. 2004 Mar;137(3):486-95. |
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Arch Ophthalmol. 2004 Apr;122(4):564-72 |
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Arch Ophthalmol. 2003 Jun;121(6):785-92. |
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Cataracts & |
Ophthalmic Epidemiol. 2003 Oct;10(4):227-40. |
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Pathophysiol Haemost Thromb. 2002 Sep-Dec;32(5-6):308-11. |
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Br J Ophthalmol. 1985 Jul;69(7):493-6. |
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Curr Opin Ophthalmol. 2002 Jun;13(3):142-6. |
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Exercise & risk taking behaviour |
Health Educ Res. 1999 Apr;14(2):225-33. |
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Am J Public Health. 1996 Nov;86(11):1577-81. |
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Arch Pediatr Adolesc Med. 2003 Sep;157(9):905-12 |
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Acad Emerg Med. 2002 Mar;9(3):209-13 |
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How much exercise do we need |
US Department of Agriculture main recommendations http://www.healthierus.gov/dietaryguidelines/ |
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Benefit of exercise preventing cardiovascular disease |
Ann Intern Med. 2001 Jan 16;134(2):96-105. |
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Exerc Sport Sci Rev. 2003 Oct;31(4):176-81. |
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Percentage benefit of exercise preventing diabetes |
JAMA. 1999 Oct 20;282(15):1433-9. |
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Exercise lowers triglycerides and increases HDL |
Sports Med. 2001;31(15):1033-62. |
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Grading Evidence |
Scottish Intercollegiate
Guidelines Network: Using this scheme the evidence quoted is of various grades, from the stongest 1++ evidence, to weaker grade 3 evidence. |
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