April 18, 2011
Study offers first look at Asian Americans’ glaucoma risk
Increased risk has implications for eye care, says Kellogg glaucoma specialist
Joshua D. Stein, M.D., M.S.
While it’s generally known that African Americans have the highest risk for glaucoma (about 12 percent), a new study reports that Asian Americans also face a significant risk of developing glaucoma, a potentially blinding disease.
By reviewing insurance records of more than 44,000 Asian Americans older than 40 years of age, Joshua D. Stein, M.D., M.S., a glaucoma specialist at the University of Michigan Kellogg Eye Center, found their glaucoma risk to be 6.5 percent, which is about the same as U.S. Latinos.
The study, funded by the National Eye Institute, was published online in February in Ophthalmology.
The findings have implications for eye care providers and more generally for health policy, says Dr. Stein, who notes that Asian Americans are the second fastest growing population in the U.S. “Clinicians should be aware that their Asian American patients are at increased risk for glaucoma and monitor them for signs of the disease.” he says. Dr. Stein adds that additional resources may be needed for efforts to improve detection of glaucoma in this growing patient population.
The study detailed the Asian American ethnic groups most likely to develop the three main types of glaucoma: open-angle glaucoma (OAG, the most common form), narrow-angle glaucoma (NAG), and normal-tension glaucoma (NTG).
The rate of NAG was higher in Asian Americans than in any other racial group in the study and highest of all among Chinese and Vietnamese Americans. With NAG, the part of the eye that drains excess fluid becomes blocked and pressure builds up in the eye; the patient usually feels severe, rapid-onset pain and needs immediate treatment to prevent vision loss.
The risk of NTG was three to 10 times higher in Japanese Americans than other Asian ethnicities studied, and nearly all of the Asian sub-groups were at higher risk than non-Asian Americans. With NTG, the optic nerve and vision sustain damage even though the pressure within the eye remains within “normal” levels. Among Asian Americans, OAG rates were highest among Japanese Americans (about 9.5 percent), followed by Indian and Pakistani Americans (about 7.7 percent).
Eye care providers should look for signs of glaucoma when evaluating Asian American patients over 40 years of age, according to the study’s authors. “For example, the inner eye angle anatomy of patients of Chinese or Vietnamese ancestry should be carefully examined,” Dr. Stein said. “And since NTG won’t be detected by simply measuring intraocular pressure (IOP), eye doctors need to assess the status of the optic nerve, and when appropriate perform visual field testing in patients whose ethnicity makes them more susceptible to this type of glaucoma,” he added.
Dr. Stein has conducted a number of studies using large health care databases, an approach that provides data for a larger and more geographically diverse group of patients than can be captured in most traditional clinical studies. He and his coauthors recommend that future studies explore potential genetic and environmental reasons for some of the observed differences in glaucoma rates among the different races and Asian ethnicities.
Citation: Differences in Rates of Glaucoma among Asian Americans and Other Racial Groups, and among Various Asian Ethnic Groups. Ophthalmology, 2011 Feb 8. [Epub ahead of print]
Other University of Michigan authors: Denise S. Kim, B.S., Leslie M. Niziol, M.S., Nidhi Talwar, M.A., Bin Nan, Ph.D., David C. Musch, Ph.D., M.P.H., Julia E. Richards, Ph.D.
Written by Betsy Nisbet