Previous studies have suggested an underutilization of eyecare services in the United States, yet increasing the density of ophthalmologists in a region that already contains one doesn’t appear to result in increased usage of services, new research published in the American Journal of Ophthalmology reports.

“While these findings corroborate known disparities in eye care utilization, public health efforts to increase access to eye care may require a more nuanced approach than simply increasing the density of ophthalmologists in a given geography,” the authors wrote in their paper.

The investigation also found a significantly higher rate of service usage in counties that were composed of smaller populations of African Americans, Hispanics and “other race” individuals. Additionally, the study noted a higher proportion of female Medicare beneficiaries used ophthalmologic services compared with males.

The study used data from the CMS, US Census Bureau, US Department of Agriculture and HUD to calculate county- and state-level ophthalmologic service usage by Medicare fee-for-service beneficiaries relative to geography-specific market saturation, demographics and contextual factors.

The overall ophthalmology service use ranged from about 58% to 15%, while saturation ranged from 21,763 to 91.4 Medicare beneficiaries per registered ophthalmologist. In addition to race and gender, usage was strongly tied to a higher proportion of adults with higher levels of education compared with those who only had a high school diploma.

Increase usage was also linked to a lower proportion of adults in each geographic region who lived in poverty, geographies with lower Multidimensional Deprivation Indexes and a higher urban-influence code.

“As ophthalmologists try to meet the needs of their local population, focus on

individual and contextual barriers may help increase realized access and improve population health,” the researchers wrote.