(Reuters Health) - Meeting physical activity guidelines and being physically fit may reduce the risk of developing glaucoma by 40 percent to 50 percent, recent research suggests.

Among nearly 10,000 people in a long-term study, even those who exercised less than the recommended 150 minutes per week had a lower risk of glaucoma than those who were completely sedentary, the study authors note in the journal Medicine and Science in Sports and Exercise.

“Glaucoma is one of the most common eye disorders and causes of blindness, however, we don’t know much about how to prevent it,” said study coauthor Duck-chul Lee of Iowa State University in Ames.

In glaucoma, the optic nerve becomes thinned. Current treatments aim to reduce intraocular, or inner-eye, pressure. Previous studies have noted that physical activity lowers that pressure.

About half of Americans don’t meet the national physical guidelines of 150 minutes of moderate intensity aerobic activity and two days of resistance exercise each week, Lee noted.

“It is important to promote physical activity to prevent glaucoma in addition to the benefits in preventing other chronic diseases such as heart attack, diabetes and cancer,” he said in an email.

The researchers analyzed data on 9,519 men and women at the Cooper Clinic in Dallas, Texas, between 1987 and 2005. Study participants had their weekly physical activity recorded and their cardiovascular fitness was measured with a treadmill test.

Lee and colleagues found that 128 new cases of glaucoma occurred during the average six-year follow-up period. People who met physical activity guidelines had a 50 percent lower risk of glaucoma than those who logged no leisure time physical activity during the week. In addition, people with the highest cardiovascular fitness results on the treadmill had a 40 percent lower risk of glaucoma than those with the lowest fitness levels.

Being both physically active and highly fit was tied to the lowest risk for glaucoma.

“The magnitude of a 40-50 percent reduced risk of developing glaucoma by being active and fit is surprising, (and) may be one of the strongest factors in glaucoma prevention besides aging,” Lee said.

The study was not designed to determine whether or how exercise or physical fitness may directly influence glaucoma risk. Another limitation is that participants self-reported their activities, so researchers can’t be certain how much they actually exercised.

“At the same time, every little additional bit of physical activity you do is beneficial,” said Dr. Pradeep Ramulu, who directs the glaucoma division of Johns Hopkins Medicine in Baltimore, Maryland, and wasn’t involved in the study.

“Patients want to know what types of exercise to do and how much to do,” he said in a phone interview. “The answer is probably that the more you do, the better.”

Physical activity could also help glaucoma patients with related mental health concerns such as depression and anxiety, noted Dr. Bonnie Choy of the University of Hong Kong who also wasn’t involved in the study.

“For those at high risk of glaucoma development, including a family history, regular eye screenings to detect early disease and initiate treatment is probably more important than only keeping fit,” she said by email.

SOURCE: bit.ly/2MmZq0a Medicine and Science in Sports and Exercise, online July 6, 2018.