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Vigorous exercise may lower IOP, eye disease risk
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 Jim Owen |
Power output during exercise affects cellular biology in many ways, some of which may lower the risk for eye disease, according to a practitioner.
“The factors we evaluate in glaucoma and macular degeneration — blood perfusion, health of the optic nerve and health of the macula — are improved after exercise at a basic science level,” Jim Owen, OD, FAAO, told Primary Care Optometry News. However, he cautioned that those factors have not been shown to be improved long-term, and other compounding variables could be an influence.
“There are also prospective epidemiological studies that say people who exercise have less macular degeneration and less glaucoma, which shows an associative relationship,” he added.
Exercise lowers IOP
In a prospective epidemiologic cohort study following 29,854 male runners (mean age 44.86 years) without glaucoma for a period of 7.7 years, the risk for incident reported glaucoma declined based on the distance and time runners completed a 10-km race, concluding that IOP decreases transiently with aerobic exercise in proportion to intensity and duration. The study authors reported that glaucoma decreased 37% per meter per second (m/s) increment in the race overall. The slowest, least fit men who ran between 3.6 m/s and 4.0 m/s had a 29% decreased risk for incident reported glaucoma, men who ran 4.1 m/s to 4.5 m/s had a 54% decrease and men who ran between 4.6 m/s and 5.0 m/s had a 51% decrease. Glaucoma was nonexistent among the fittest and fastest men (781) who exceeded 5.0 m/s.
In Passo’s study where maximum aerobic capacity and IOP were compared in 13 sedentary adults who were put on a controlled exercise program, he found a 30% increase in aerobic capacity along with a 20% reduction in IOP, Dr. Owen said. Both measures returned to baseline after the exercise programs where stopped.
Questions arise related to the amount, duration and intensity of physical activity to have a sustainable effect on IOP. “Since we can measure activity in power output or watts, that variable could be controlled in well designed study,” he added.
Mechanism of lowered IOP unknown
Though it is known that IOP declines during exercise, the specific factors that provoke that response are still unknown. In an experimental procedure from the Medical Sciences Program and School of Optometry at Indiana School of Medicine, researchers found that acute dynamic exercise and isosmotic fluid ingestion each seem to change IOP through changes in colloid osmotic pressure (COP). Standardized exercise in both hydrated and dehydrated subjects significantly reduced IOP and elevated COP, which suggests that factors linked to capillary infiltration explain acute IOP reductions in exercise, the study authors said.
Though more study is needed to determine the role exercise plays in eye health, Dr. Owen emphasized the importance of talking to at-risk patients about their diet and exercise habits.
“When the average patient asks what they can do for their eyes, I say, ‘What’s good for you is good for you,’ meaning the lutein in spinach and the omega-3s in salmon and exercise are all good for your heart, your respiratory system and your eyes. I think it’s so much more effective because patients don’t expect it from me. If you [advocate a healthy lifestyle] in your practice by taking a few minutes to discuss the importance of diet and exercise, your patients will benefit.”
Dr. Owen presented, “The Role of Nutrition and Exercise for Eye Care Patients” during Vision Expo West in Las Vegas, focusing on the physiology and role of exercise, published studies and ways clinicians can incorporate this holistic approach into their practices. — by Stephanie Vasta
References:
- Martin B, Harris A, Hammel T, Malinovsky V. Mechanism of exercise-induced ocular hypotension. Invest Ophthalmol Vis Sci. 1999;40(5):1011-1015.
- Passo M. Exercise training reduces intraocular pressure in subjects suspected of having glaucoma. Arch Ophthalmol. 1991;109:1096-1098.
- Williams PT. Relationship of incident glaucoma versus physical activity and fitness in male runners. Medicine & Science in Sports & Exercise. 2009; doi: 10.1249/MSS.0b013e31819e420f.
- Jim Owen, OD, FAAO, can be reached at Encinitas Optometry, 1279 Encinitas Blvd., Encinitas, CA. 92024; (760) 436-1877, fax: (760) 632-7319; encinitasod@cox.net.
