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.