This study found that among CMS-enrolled providers, there are currently 52.60 ophthalmologists and 100.55 optometrists per million Americans, with state-level variations. However, when including those not enrolled with Medicare, the actual number of practicing ODs is much higher. Photo: Getty Images.

Two ophthalmologists recently conducted an analysis of geographic access to eye care across the United States, as travel burden of eyecare is commonly cited as a reason for optometric scope expansion. The results purport to show that almost all Americans live within an hour’s drive to both an ophthalmologist and optometrist. However, a flawed research design undermines the validity of these claims; in addition to misrepresenting the number of optometrists in practice across the country, the study also neglected various factors aside from drive time that influence access to care.

The most glaring methodological flaw in this research, according to Richard Edlow, OD, known as “The Eyeconomist,” is its reliance on data from providers enrolled in the Doctors and Clinicians National File from the Centers for Medicare & Medicaid Services (CMS) and the assumption that this is an accurate accounting of eyecare professionals in the US. In total, the study geocoded locations for 17,417 ophthalmologists (30,770 addresses) and 33,291 optometrists (46,099 addresses).

“While 17,417 ophthalmologists is a pretty accurate estimate (my data tracking indicates 17,312), the number of optometrists in the US is grossly incorrect,” comments Dr. Edlow. “There are, in fact, 49,360 practicing optometrists in the country with only 33,291 misleadingly utilized in the study. The authors failed to understand that, as many optometrists are the nation’s front line of primary eye care, not all are participating providers with CMS/Medicare.” He points out that “this failure missed out on 16,069 practicing optometrists around the country, or roughly one-third of all ODs.”

Keeping this caveat in mind, the present analysis showed that, among CMS-enrolled providers, there are roughly 52.60 ophthalmologists and 100.55 optometrists per million Americans, with variations between states. The researchers claimed in their paper, published last week in Ophthalmology, “An estimated 74.94%, 90.78% and 97.80% of Americans reside within 15, 30 and 60 minutes of an ophthalmologist, respectively; for optometry, the corresponding proportions are 84.52%, 95.16% and 98.54%.” While the figures for one-hour access to MDs and ODs are nearly equivalent (97.8% vs. 98.5%) even with the undercounting of optometrists done in this study, those for the shorter commutes surely underrepresent access to optometry, as the study omits one-third of the profession.

The researchers identified 212 counties (6.74%) with over >50% of their population living within an hour of a CMS-participating optometrist but not an ophthalmologist, while just eight counties (0.25%) are within an hour of an ophthalmologist but not an optometrist. In 166 counties (5.28%), most residents live beyond 60 minutes of either provider type.

At face value, these results give the impression that geographic eyecare accessibility is a marginal issue pertinent only to select regions of the country; however, it’s important to recognize the many factors excluded from this study that affect patients’ ability to receive timely care. One of these, Dr. Edlow points out, is eyecare subspecialization. “This is significant, as initial access to the eyecare system is rarely, if ever, initiated in a subspecialist’s office,” he says. “By my count, in 2024, utilizing membership in the subspecialty organizations, there are approximately 5,000 subspecialty ophthalmologists, leaving just over 12,200 as general ophthalmologists.” Dr. Edlow argues, “The study would have been best served using the number of ophthalmologists at 12,200 and optometrists at 49,300 resulting in a significantly different conclusion.”

In other words, access does not equal appropriateness. Proximity to a glaucoma surgeon is of little use to an AMD patient needing anti-VEGF injections or a 10-year-old needing glasses.

The ”Eyeconomist” also points out that the study’s measurement for access to care—drive time—doesn’t speak to the real-time availability of those providers. “I would suggest future studies include a significant sampling of next available appointment time by doctor and location,” he says.

Finally, Dr. Edlow argues that “the study is looking in the rear-view mirror” by failing to consider the dwindling ophthalmology workforce amidst a growing demand for care. “To truly consider public health issues and access to care, one must be forward-thinking,” he states. “The supply of ophthalmologists is increasing, at best, by 0.4% per year while the demand for age-related eye care is increasing by 3.0% per year. Every year, moving forward, will result in decreased access to ophthalmologists in the US.”

If there’s one aspect of this research suitable to real-world circumstances, it may be the spotlighting of commonalities between regions where eyecare access still falls short. Two demographic factors they found associated with reduced access were ethnic homogeneity and socioeconomic status. “[Census] tracts with greater racial and ethnic homogeneity and higher proportions of Medicare-aged and uninsured residents demonstrate significantly higher odds of reduced geographic access (i.e., >60min travel time) to both ophthalmic and optometric care,” the researchers wrote. “Moreover, tracts with a greater proportion of college-educated residents exhibit significantly lower odds of reduced access to both types of eyecare providers.”

In their paper, the study authors posit that their results “are not evidence in favor of optometric scope of practice expansion,” a viewpoint that is inherently flawed considering the study’s underrepresentation of optometrists and use of drive time as the sole measure of accessibility. They then go on assert without evidence that, compared to optometrists, ophthalmologists “may yield improved outcomes” in the surgical management of various eye diseases. However, a study published last month in Clinical and Experimental Optometry undercuts this claim, reporting a complication rate of just 0.001% for optometrist-performed laser and minor surgical procedures.

In conclusion, the researchers propose that this data may be used to “direct geographically targeted initiatives such as hospital system-backed mobile health efforts or county-sponsored incentives for practice establishment in underserved areas,” while adding that more research is needed “to better understand the drivers and significance of these apparent disparities.” One could argue that an entirely new study—which includes an accurate count of ODs and MDs and considers additional aspects of accessibility—is necessary to truly assess the state of geographic eyecare access in the US.