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Higher fitness levels in older adults can help reduce risk of glaucoma

It’s estimated by 2020 that 80 million additional people will be diagnosed with glaucoma — an acquired optic neuropathy characterized by the thinning of the neuroretinal rim of the optic nerve and the enlargement of the optic nerve cup, according to research — Physical Activity, Cardiorespiratory Fitness and Incident Glaucoma — appearing in the November issue of Medicine & Science in Sports & Exercise.

Researchers from Iowa State and South Carolina University noted that “nearly 570 million people worldwide suffer from visual impairment, low vision or blindness, of which an estimated 80 percent is attributed to preventable causes. Glaucoma is the second-leading cause of blindness and has led to blindness in 8 million people.”

In addition to the modifiable risk factor of intraocular pressure (IOP), other risk factors for glaucoma include:

  • High nearsightedness.
  • Age.
  • Race (African Americans, Hispanics)
  • Diastolic diffusion pressure.
  • Family history.
  • Thin central cornea.
  • Inflammation.
  • Low levels of physical activity.
  • High blood pressure in older adults.
  • Refractive error.
  • Optic disc diameter.
  • Cardiovascular disease.

“A recent review of physical activity and IOP showed clear benefits of acute exercise and an inverse relationship between physical fitness and IOP,” according to the researchers, who also commented that long-term data is inadequate.

To establish the long-term effect of physical activity on reducing the incidence of glaucoma, data was used from consenting participants, who had medical examinations between 1987 and 2005 at the Cooper Clinic in Dallas and enrolled in the Aerobics Center Longitudinal Study.

Study highlights included:

9,890 40-year-old and older participants — with at least one year of follow-up — who didn’t report glaucoma at baseline.

Achieving 85 percent of their age-predicted maximal heart rate (220-age) on a treadmill stress test.

Completing a comprehensive medical questionnaire (lifestyle habits, past and present chronic disease history).

Having a clinical medical examination, along with assessment from 12-hour fasting blood chemistries, resting blood pressure and body mass index, among other variables.

Physical activity was assessed from self-reported leisure time or three-month recreational activities to assess MET-minutes per week based on the 2008 Physical Activity Guidelines for Americans. A MET is the ratio of energy expended during an activity compared to the energy expended at rest.

The recommended public physical activities guidelines include 150 minutes of moderate intensity or 75 minutes of vigorous intensity weekly aerobic exercise. The participant activity categories classified 0 MET-minutes per week as inactive, less than 500 MET-minutes per week as insufficient, and greater than 500 weekly MET-minutes, as meeting the recommended 2008 guidelines.

Researchers said “this study demonstrated that meeting the 2008 Physical Activity Guidelines for Americans recommending the (weekly) 500 MET-minutes was associated with a lower risk for incident glaucoma after controlling for potential confounders, including lifestyle and health risk factors.”

As to how the prescribed physical activity might reduce the risk to glaucoma, the researchers commented that “some evidence suggests that exercise stimulates antioxidant networks. Oxidative stress may damage retinal ganglion cells and damage DNA in the trabecular meshwork, thereby compromising outflow and increasing IOP, and increased oxidative stress has been linked to IOP in animal models.”

All of which led to the conclusion that “physical activity, when meeting the recommended guidelines, and higher level of fitness (upper third) was associated with a lower risk of incident glaucoma, compared with inactive or lower level of fitness (lower third). Being fit in addition to being active may provide further protection from developing glaucoma.”

Fitness is the easiest, most inexpensive, non-exclusionary club to join. It invites all people to participate, and it offers those with health issues, with proper guidance, a path to longevity.

It requires commitment over contribution to realize the benefits. Why not saddle up and ride this horse across the finish line — to a higher quality of life.

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