Findings from a recent study published in Ophthalmology assessed how many Americans live within an accessible distance of an eye care provider (ECP) and identified the geographic areas that lack easy access to eye care.
Give me some background.
A 2016 study using 2010 Census data demonstrated that more than 90% of the U.S. Medicare beneficiary population lives within a 30-minute drive of an ophthalmologist and within 15 minutes of an optometrist—though there were regional variations.
- However: The study authors noted that this analysis only included primary provider locations and did not allow for interstate travel—potentially resulting in underestimated proximity.
Consequently: The focus of this study was to present an updated nationwide assessment of geographic access to eye care and characterize the demographic composition of populations with reduced access.
Talk about the study.
In this retrospective study, investigators compiled a list of U.S. ophthalmologists and optometrists using the Doctors and Clinicians National File from the Centers for Medicare and Medicaid Services (CMS).
Addresses from CMS were geocoded onto 2022 Census tract maps, which were then further annotated with self-reported demographic data from the 2018-2022 5-year estimates of the American Community Survey.
About this survey …
The American Community Survey is an annual survey administered by the U.S. Census to assess a representative sample of American households and collects information such as:
- Age
- Race
- Income
- Education
- Insurance type
Keep going…
A threshold of 60 minutes was used to classify census tracts as having either adequate (i.e., within 60 minutes) or reduced access (i.e., >60 minutes).
County proximity to eye care was classified by calculating the proportion of a given county’s population residing in tracts previously classified as within 15, 30, or 60 minutes from access to eye care.
The county as a whole was then classified within a level of proximity (15, 30, 60, or 60+ minutes) if the majority of the population (>50%) was found to reside at the corresponding level of proximity.
Findings?
Locations for 17,417 ophthalmologists (30,770 addresses) and 33,291 optometrists (46,099 addresses) were included in the analysis.
There were 52.60 ophthalmologists and 100.55 optometrists per million Americans, with state-level variations.
Further: An estimated 74.94%, 90.78%, and 97.80% of Americans resided within 15, 30, and 60 minutes of an ophthalmologist, respectively—for optometrists, the corresponding proportions were 84.52%, 95.16%, and 98.84%.
Talk about demographics and geographic access to eye care?
Based on multivariate logistic regression, tracts with greater racial and ethnic homogeneity and higher proportions of Medicare-aged and uninsured residents demonstrated significantly higher odds of reduced geographic access to both ophthalmic and optometric care.
In addition: Tracts with a greater proportion of college-educated residents exhibited significantly lower odds of reduced access to both types of eye care providers.
Tell me more.
Although tracts with a greater proportion of pediatric-aged residents exhibited significantly higher odds of reduced access to ophthalmic care, they showed significantly lower odds of reduced access to optometric care.
Moreover, the tract-level proportion of very low-income residents (i.e., individuals in households below the poverty line) was not significantly associated with geographic access to either ophthalmic or optometric care.
How many counties had reduced geographic access to eye care?
There were 212 counties (6.74%) with a population majority within an hour of an optometrist but not an ophthalmologist, while eight counties (0.25%) were within an hour of an ophthalmologist but not an optometrist.
In 166 counties (5.28%) the population majority resided beyond 60 minutes of either provider type.
Limitations?
Only CMS-enrolled providers were included in the study, and for each provider, the treatment of all ages was presumed and subspecialization was not considered.
Further: They could not account for unequal time spent across primary and satellite locations, and alternative modes of transportation (other than driving) were not included in the analysis.
How did these limitations affect the study outcomes?
In a Review of Optometry article, Richard Edlow, OD, described inconsistencies in the study’s research design, such as:
- There are 49,360 practicing optometrists in the country (vs. the 33,291 used in the study, which missed roughly ⅓ of all American optometrists), as not all optometrists are participating providers with CMS/Medicare
- There are approximately 5,000 subspecialty ophthalmologists, leaving just over 12,200 general ophthalmologists—though the study included all ophthalmologists in the analyses
- Access to care measured by driving time doesn’t capture the real-time availability of eye care providers
- The study did not consider the declining ophthalmology workforce amidst a growing demand for eye care; meaning each year, there will be decreased access to ophthalmologists in the US
Take home.
These findings suggest that 98% and 99% of Americans live within an accessible distance (60 minutes) from an ophthalmologist and optometrist, respectively.
However: Due to the study design, readers are recommended to interpret these findings with caution.
Next steps?
The study also identified granular geographic data to identify counties that remained beyond a navigable distance from eye care.
This data could be used to directly geographically targeted initiatives, such as hospital system-backed mobile health efforts or county-sponsored incentives for practice establishment in underserved areas.