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Study finds high prevalence of glaucoma in rural northern China

More than 90% of primary open-angle glaucoma cases were previously undetected, and the prevalence of all glaucoma types increased with age.

Issue: April 2012

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The prevalence of glaucoma in a rural population in northern China proved to be similar to that of other Asian populations, according to a large population-based study.

Glaucoma was severely underdiagnosed and unilateral glaucoma-related blindness was highly prevalent in the population, the researchers said.

The study examined the prevalence of both primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG).

“The most significant findings from the study were that the ratio of PACG to POAG was approximately equal,” Huiping Yuan, MD, PhD, the corresponding author, said in an email interview with Ocular Surgery News. “More than 90% of POAG cases previously were undetected, and nearly 30% of subjects with glaucoma were blind in at least one eye.”

The number of Chinese citizens older than 60 years is expected to rise from 174 million to 248 million by 2020, according to estimates by the China National Committee on Aging. Many rural Chinese residents lack adequate information and access to eye care, Dr. Yuan said.

“The increasing prevalence of the disease and a rapidly aging population are significant indications that the problems and health complications caused by glaucoma may increase significantly in the near future,” Dr. Yuan said. “Information and prevention campaigns to raise glaucoma awareness in high-risk populations could have a positive impact on visual health and need to be implemented and studied.”

The study was published in Ophthalmology.

Patients and procedures

The population-based, cross-sectional survey study included 5,197 subjects 40 years of age and older living in Kailu County, Tongliao, Inner Mongolia. Complete data were available for 5,158 subjects. Mean patient age was 55.87 years.

The International Society of Geographical and Epidemiologic Ophthalmology criteria were used to diagnose glaucoma.

Subjects underwent extensive interviews and complete ophthalmic examinations that included applanation tonometry, central corneal thickness measurement, gonioscopy, slit-lamp examination, dilated fundus evaluation and visual field testing.

Findings and conclusions

Age- and gender-adjusted data showed that of the 5,197 patients responding to the survey, 169 (3.28%) had glaucoma. Of the 169 cases of glaucoma, 73 (43%) had POAG, 90 (53%) had PACG, and six (3.55%) had trauma-related, neovascular or lens-related glaucoma.

Overall, the adjusted prevalence of glaucoma was 2.9%. The ratio of PACG to POAG was roughly equal.

Results showed that 4.1% of subjects with POAG and 60% of those with PACG had previous diagnoses.

Unilateral blindness from primary glaucoma was identified in 27 subjects. Bilateral blindness was identified in 12 subjects, six with PACG and six with POAG.

The prevalence of all glaucoma types increased with age, the researchers said.

A large proportion of subjects with glaucoma had normal IOP, Dr. Yuan said.

“Of the 73 participants with POAG, 47 had IOP of 21 mm Hg or less,” she said. “Fifty-two of the 90 participants with PACG and one of the six participants with secondary glaucoma also had IOP of 21 mm Hg or less, suggesting that screening for glaucoma based on IOP measurements may not be effective.”

Limitations of the study included a lack of optic disc stereophotographs, an accurate, objective tool for measuring vertical cup-to-disc ratio, but subjective grading of vertical cup-to-disc ratio proved highly reliable, the researchers noted. – by Matt Hasson

Reference:

Song W, Shan L, Cheng F, et al. Prevalence of glaucoma in a rural northern China adult population. Ophthalmology. 2011;118(10):1982-1988.

For more information:

Huiping Yuan, MD, PhD, can be reached at Department of Ophthalmology, The 2nd Affiliated Hospital, Harbin Medical University, 246 Xuefu Road, Harbin, Heilongjiang 150086, P. R. China; email: yuanhp@yahoo.com.

Disclosure: Dr. Yuan has no relevant financial disclosures.