Increased awareness key to preventing blindness from glaucoma

Ophthalmologists can affect rates of blindness from glaucoma by decreasing IOP variability and diagnosing the disease early.

Anne L. Coleman

Ophthalmologists can help prevent blindness from glaucoma by increasing their awareness of its risk factors and employing proven approaches for managing patients with glaucoma, such as decreasing IOP variability and encouraging them to follow prescribed treatment regimens.

In the literature, rates of glaucoma-related blindness range from 15% to 25% in one eye and from 6% to 10% bilaterally, according to Anne L. Coleman, MD, PhD. At Hawaiian Eye 2009, she discussed the risk factors for going blind from glaucoma, such as older age, race/ethnicity, initially presenting with late-stage glaucoma, variable IOP, poor treatment compliance and residing in a developing country.

“It might be that by modifying these risk factors, we might be able to prevent people from eventually going blind from glaucoma,” Dr. Coleman said.

“Worldwide, the greatest risk factor for blindness is actually being a resident of a developing country,” she said, citing research by Chen et al.

The age factor

Patients who are older when first diagnosed with glaucoma may be at increased risk of eventual blindness, according to Dr. Coleman. In a study by Oliver et al, age at diagnosis of glaucoma was about 69 years in those who later went blind, compared with 65 years in those who did not (P = .03). One explanation for this difference is that more advanced disease is typically associated with older patient age. However, she said, another study showed little or no association between age at the time of glaucoma diagnosis and risk of blindness.

Controlling for severity of the disease may greatly reduce the effect of age, Dr. Coleman said.

“One of the things we do know is that older individuals can be more likely to go blind … because they have usually had the disease longer, so they have a greater risk for becoming blind,” she said.

Reducing IOP variability

Oliver et al identified an association between IOP fluctuation and risk of blindness in individuals with glaucoma. Investigators found a greater likelihood of blindness when IOP varied by about 10 mm Hg. Blindness occurred less frequently when IOP only fluctuated about 7 mm Hg.

“Besides following patients more closely and being cognizant of their intraocular pressure fluctuation, increasing compliance with treatment regimens, getting patients involved in their care and getting them adherent … might make a difference,” Dr. Coleman said.

Developed vs. developing countries

Among those factors that cannot be changed are race, ethnicity and the country in which an individual with glaucoma resides. “In the United States, we have found glaucoma-related blindness is associated with race and ethnicity, which may be secondary to genetic factors,” Dr. Coleman said.

In the United States, blindness rates from glaucoma vary from about 6% in whites to 26% in African-Americans and 28% in Hispanics.

“Interestingly, where an individual with glaucoma resides may affect their risk of blindness from glaucoma,” she said.

Progression to bilateral blindness is relatively rare in developed countries, but rates of progression are much higher in developing countries. In some areas of the world, one in three individuals with glaucoma goes bilaterally blind. Part of the problem may stem from lack of awareness. In developing countries, more than 90% of people may be unaware they have glaucoma because they have never been evaluated, Dr. Coleman said.

Being a U.S. resident seemingly protects people from glaucoma-related blindness, presumably because of better access to care and awareness.

However, “despite better access to care and awareness, we do have individuals who are blind secondary to glaucoma in the U.S.,” she said. – by Susan M. Rapp

References:

• Chen PP. Risk and risk factors for blindness from glaucoma. Curr Opin Ophthalmol. 2004;15(2):107-111.
• Oliver JE. Hattenhauer MG, Herman D, et al. Blindness and glaucoma: A comparison of patients progressing to blindness from glaucoma with patients maintaining vision. Am J Ophthalmol. 2002;133(6):764-772.

• Anne L. Coleman, MD, PhD, the Frances and Ray Stark Professor of Ophthalmology and Epidemiology at the University of California-Los Angeles Jules Stein Eye Institute, can be reached at UCLA, 100 Stein Plaza 2-118, Los Angeles, CA 90095-7004; 310-825-5298; fax: 310-206-7773; e-mail: colemana@jsei.ucla.edu.