PRIMARY CARE OPTOMETRY NEWS October 1, 2010
Vigorous exercise may lower IOP, eye disease risk
Jim Owen, OD, FAAO
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
* 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; firstname.lastname@example.org.
And here's another one linking exercise to a lower incidence of age related macular degeneration:
Vigorous running was associated with a reduced incidence of age-related macular degeneration in a large study. Male former cigarette smokers and people who ate more meat and less fruit had a higher incidence of AMD.
The prospective cohort study included 29,532 men and 12,176 women age 18 years and older participating in the National Runners' Health Study. Subjects completed a questionnaire on demographics and running, weight, smoking and medical histories. Investigators followed the cohort for 7.7 years.
The results showed AMD reported by 110 men and 42 women. Those reporting AMD were older (mean 54.81 years) than those not reporting AMD (mean 44.86 years).
Men who reported AMD were significantly more likely to have formerly smoked cigarettes (50.6%) than those who did not report AMD (41.2%). Men and women who ate more meat and less fruit were more likely to report AMD.
In addition, men and women reporting AMD ran significantly less than those who did not have AMD; relative risk for AMD diminished 10% for each kilometer run daily, the study author said.
Limitations of the study included incident AMD being self-reported, a lack of data on type of AMD reported (wet vs. dry) and the absence of a sedentary control group.
And while we're at it, here's one linking obesity to increased risk of age-related macular degeneration:
Overall and abdominal obesity increase the risk for progression of age-related macular degeneration, while exercise tends to decrease the risk, researchers with the Massachusetts Eye and Ear Infirmary found.
Johanna Seddon, MD, ScM, and colleagues studied 261 participants who were at least 60 years of age and had some sign of nonadvanced age-related macular degeneration (AMD) and visual acuity of 20/200 or better in at least one eye. Average follow-up was 4.6 years.
The researchers found that patients with a higher body mass index (BMI) had increased risk for AMD progression. Patients whose BMI was between 25 and 29 (considered overweight) or greater than 30 (considered obese) were more than twice as likely to experience worsening of AMD as patients with a BMI of less than 25. People with the largest waists had a twofold increased risk for progression over those with the smallest.
“In our study population, 38% of the men and 57% of the women had abdominal obesity and 22% of men and 26% of women had overall obesity. A decade ago, we had little advice for patients with AMD, and now we have an extensive body of evidence regarding modifiable factors to disseminate,” the authors reported in the June issue of Archives of Ophthalmology.
Additionally, more physical activity tended to be associated with a reduced rate of AMD progression, with a 25% reduction in progression rate for patients who underwent vigorous activity three times a week.