Severe vision loss is disproportionately prevalent in counties located in the southern United States that have high poverty levels, according to a Centers for Disease Control and Prevention (CDC) report.

The researchers used data from the American Community Survey to estimate the county-level prevalence of severe vision loss (SVL), defined as blindness or having serious difficulty seeing even when wearing glasses. They determined that "77.3% of counties in the top SVL prevalence quartile...were located in the South." In addition, SVL was significantly correlated with poverty.

Of the 437 counties in the top quartiles for both SVL and poverty, 83.1% were located in southern states, Karen A. Kirtland, PhD, from the Division of Diabetes Translation at the CDC's National Center for Chronic Disease Prevention and Health Promotion, Atlanta, Georgia, and colleagues report in an article published in the May 22 issue of the Morbidity and Mortality Weekly Report.

Most current surveillance activities characterize vision loss at national and state levels; however, interventions and policy decisions to reduce the burden of vision loss and eliminate care disparities are typically developed at the local level, where there are limited data and research, the authors write.

To obtain a county-level view of SVL prevalence, the investigators analyzed data from the combined 2009 to 2013 surveys representing 3143 counties. They divided the counties into quartiles based on SVL prevalence and divided the counties into quartiles based on the proportion of residents living below the poverty level. The researchers then compared the prevalence of SVL and poverty by US Census regions.

SVL prevalence was highest in the counties in the South (77.3%), followed by those in the West (11.7%), the Midwest (10.7%), and the Northeast (0.3%).

Across all counties, the proportion of individuals living below poverty level ranged from 1.3% to 48.8% (median, 13.9%). Most of those counties (74.5%) were located in the South, followed by the Midwest (13.1%), the West (11.5%), and the Northeast (0.9%).

More than half (55.5%) of the counties in the top quartile for SVL prevalence were also in the top quartile of poverty, and county prevalence of SVL was significantly associated with county poverty (correlation coefficient, 0.5; P < .0001). "Eight states had at least 6% of their counties in the top quartile for both SVL and poverty: Alabama, Arkansas, Georgia, Kentucky, Mississippi, North Carolina, Tennessee, and Texas," the authors write. No county in the Northeast was in the top quartile for both SVL prevalence and poverty; 9.1% were in the West, and 7.8% were in the Midwest.

The county-level correlations between SVL and poverty "are consistent with U.S. Census reports of lower earnings and higher poverty rates among persons with disabilities," the authors write, noting that more than 4 million adults older than 40 years in the United States are either blind or have vision loss, which "affects activities of daily living, leads to depression and social isolation, and increases the risk for falls and injuries."

Vision loss could be a consequence of poverty, reflecting a lack of access to care and lower use of preventive services, or poverty could be attributable to vision loss, the authors write. Individuals with vision loss "often have limited access to education and employment opportunities, which might in turn decrease their earning potential."

Although the data represent "crude estimates" of SVL prevalence and the correlation with poverty without consideration of other factors, such as race/ethnicity, age, and comorbidities, the distinct geographic disparities point to the need for additional research into sociodemographic disparities of vision loss, the authors advise.

"This report highlights how important it is to understand the complexities associated with vision loss," according to Anne Coleman, MD, PhD, a clinical spokesperson for the American Academy of Ophthalmology. "In particular, it underscores the need to investigate further the connections among severe vision loss, poverty, and access and utilization of eye care at the local level."

An improved understanding of these factors, she told Medscape Medical News, will enable the development of more effective interventions and will help providers serve the at-risk population more effectively.

The authors and Dr Coleman have disclosed no relevant financial relationships.

Morb Mortal Wkly Rep. 2015;64:514-517. Full text