Patients With Myopia at Increased Risk for Glaucoma

SAN FRANCISCO, California — Patients with myopia have an increased risk for visual field defects, and could be more likely to develop glaucoma, according to a new study.

We found that "visual field defects increased with the severity of myopia," said lead author Mary Qiu, a medical student at the University of California, San Francisco. She presented the results here at the American Glaucoma Society (AGS) 23rd Annual Meeting.

Compared with people with normal vision, those with mild myopia had a 2-fold increased risk for visual field defects, those with moderate myopia had a 3-fold increased risk, and those with severe myopia had a 14-fold increased risk, Qiu reported.

First results from the cross-sectional epidemiologic study were published in the January issue of Investigative Ophthalmology and Visual Science.

The study involved 5277 participants in the National Health and Nutrition Examination Survey (NHANES). All subjects were at least 40 years of age and had not undergone cataract or refractive surgery.

The researchers found that the odds of any visual field defects were significantly greater in those with mild myopia (odds ratio [OR], 2.02; confidence interval [CI], 1.28 - 3.19), moderate myopia (OR, 3.09; CI, 1.42 - 6.72), and severe myopia (OR, 14.43; CI, 5.13 - 40.61), than in those with normal vision.

However, they found no significant increase in the risk for self-reported glaucoma in participants with mild myopia (OR, 0.90; CI, 0.56 - 1.45), moderate myopia (OR, 1.40; CI, 0.62 - 3.16), or severe myopia (OR, 0.26; CI, 0.08 - 0.80), compared with those with normal vision.

They also found no significant increase in the risk for a vertical cup-to-disc ratio of at least 0.7 in those with mild myopia (OR, 0.84; CI, 0.31 - 2.25), moderate myopia (OR, 0.37; CI, 0.04 - 3.57), or severe myopia (OR, 0.85; CI, 0.09 - 8.42).

As the researchers report, their findings indicate that people with myopia and visual field defects could have had asymptomatic or undiagnosed glaucoma. Vertical cup-to-disc ratio can be more difficult to assess in people with myopia, because they are more likely than those with normal vision to have tilted optic nerves that are anatomically abnormal or larger optic nerve heads, Qui explained.

"The study raises concerns that whether people with myopia may not be aware that they have glaucoma," said Andrew Iwach, MD, a spokesperson for the American Academy of Ophthalmology and executive director of the Glaucoma Center of San Francisco.

"One of the challenges with glaucoma is that the early symptoms affect just peripheral vision; studies tell us that half of those with glaucoma may not be aware of it," Dr. Iwach added.

He pointed out that an increasing number of people with myopia undergo refractive surgery, and they might not be getting regular eye exams because they no longer need corrective lenses.

"People who are nearsighted may be at higher risk for glaucoma, and so it's important for them to see an ophthalmologist regularly," Dr. Iwach explained. "Then if glaucoma is found, we can start to manage the disease."

Ms. Qiu and Dr. Iwach have disclosed no relevant financial relationships.

Invest Ophthalmol Vis Sci. 2013;54:830-835. Abstract

American Glaucoma Society (AGS) 23rd Annual Meeting: Abstract 22. Presented March 2, 2013.