The incidence of new glaucoma diagnoses in the United States varies greatly across different geographic areas, according to a study in the April 3 online version of Ophthalmology. The researchers believe that clinicians in certain regions may be more likely to either underdiagnose or overdiagnose various forms of the disease, including both angle-closure glaucoma (ACG) and open-angle glaucoma.

In this study, the researchers examined a random sample of Medicare claims submitted by eye care providers from 2002 to 2008 across nine large geographic regions and 179 subregions. 

After completing their data analysis, the researchers determined that individuals who live in New England or the Mid-Atlantic states are approximately 30% more likely to be diagnosed with glaucoma than those who live in the Southeastern states.

In particular, the data suggested that ACG is largely underdiagnosed throughout most of the country. By contrast, the researchers determined that New York City in particular had the highest proportion ACG diagnoses across all analyzed regions—indicating that clinicians there are either overdiagnosing the condition or are detecting it more effectively than eye care providers located elsewhere. 

“We’re seeing that potentially both physicians and patients in [predominantly rural] areas are not getting the health care that would be obtained in a large, urban setting,” said study coauthor Harry Quigley, M.D., professor of ophthalmology and director of the Glaucoma Service at the Wilmer Eye Institute of Johns Hopkins University in Baltimore.

The authors concluded that eye care providers throughout the entire country must improve efforts to perform gonioscopy on a regular basis to ensure a proper, more accurate diagnosis of ACG. Additionally, they noted that elevated ACG diagnosis rates in New York City warrant further investigation.

Cassard SD, Quigley HA, Gower EW, et al. Regional variations and trends in the prevalence of diagnosed glaucoma in the medicare population. Ophthalmology. 2012 Apr 3. [Epub ahead of print]