Purpose
To describe temporal and geographic trends in the US eye care workforce.
Design
Cross-sectional study.
Methods
We obtained data from the 2017 Area Health Resources File. The main outcomes were ophthalmologist and optometrist density, as defined as the number of providers per 100,000 individuals, the ratio of ophthalmologists ≥55 years of age to those <55 years of age, and county characteristics associated with the availability of an ophthalmologist.
Results
From 1995 to 2017, the national ophthalmologist density decreased from 6.30 to 5.68 ophthalmologists per 100,000 individuals. Although rural counties experienced a mean annual increase in ophthalmologist density by 2.26%, they still had a lower mean ophthalmologist density (0.58/100,000 individuals) compared with nonmetropolitan (2.19/100,000 individuals) and metropolitan counties (6.29/100,000 individuals) in 2017. The ratio of older to younger ophthalmologists increased from 0.37 in 1995 to 0.82 in 2017, with the greatest ratio increase occurring in rural counties (0.29 to 1.90). The presence of an ophthalmologist was significantly associated with a greater proportion of individuals with a college degree and health insurance, and more developed health care infrastructure. From 1990 to 2017, the density of optometrists increased from 11.06 to 16.16 optometrists per 100,000 individuals.
Conclusions
Over the last 2 decades, the national density of ophthalmologists has decreased and the workforce has aged. In contrast, the density of optometrists has increased. Rural counties continue to have a disproportionately lower supply of eye care providers, although some growth has occurred. Given the rising ratio of optometrists to ophthalmologists, it is of interest for future work to determine how the optometrist workforce can best complement potential shortages of ophthalmologists.
Highlights
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The national density of ophthalmologists decreased from 1995 to 2017.
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The ophthalmologist workforce has aged.
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There continues to be a rural/urban disparity in ophthalmologist availability.
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Ophthalmologist availability was associated with existing health infrastructure.
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The national density of optometrists increased from 1990 to 2017.
Projections of physician supply and demand by the United States (US) Department of Health and Human Services report ophthalmology as the surgical specialty with the greatest predicted workforce shortage by 2025. An aging US population and increasing prevalence of systemic diseases with associated ophthalmic sequalae, such as diabetes and hypertension, have contributed to a rapidly growing patient population that is expected to outpace the supply of ophthalmologists. , In contrast, workforce projections of optometrists indicate that the projected supply of optometrists is expected to exceed projected demand. Given that previous work has demonstrated that the local availability of eye care providers is associated with improved patient awareness of disease, screening frequency, and even visual health outcomes, it is of interest to characterize and understand the distribution of ophthalmologists and optometrists in the United States.
Previous research examining the geographic distribution of eye care providers has reported disparities in ophthalmologist and optometrist availability among different counties in the United States. A study using data from 2011 found that areas with greater rural populations had a lower density of both types of eye care providers. However, we are unaware of any updated reports of the national distribution of the eye care workforce in our literature review. Furthermore, temporal trends in the workforce have not been described since 1970. Lastly, as the number of initiatives to increase rural health care providers has grown over the past decade, more recent workforce data is required to assess how these programs have impacted the distribution of ophthalmologists and optometrists.
Therefore, the purpose of this study was to describe changes in the US ophthalmologist and optometrist workforces over the last 2 decades. Specifically, we 1) examined the density of ophthalmologists and optometrists at a county level over time; 2) compared rural vs urban differences; 3) assessed changes over time in the age of the ophthalmologist workforce; and 4) determined county characteristics associated with the presence of an ophthalmologist.
Methods
This is a cross-sectional study using data from the 2017 Area Health Resources File (AHRF), a product of the US Department of Health and Human Services that combines data from >50 sources. The AHRF reports the number of ophthalmologists per county using data from the American Medical Association Physician Masterfile, as well as various county characteristics. Data on the number of ophthalmologists participating in patient care were available for the years 1995, 1997-2008, and 2010-2017. Optometrist data were available for the years 1990, 2000, and 2009-2017. We collected county-level population data from the 2017 Census Population Estimates. This study was prospectively exempted by the Yale University Institutional Review Board, as the data are publicly available, and adhered to the tenets of the Declaration of Helsinki.
Measures
The primary outcome measures of this study were the densities of practicing ophthalmologists and optometrists, defined as the number of providers per 100,000 individuals. Additional outcomes were the ratio of ophthalmologists ≥55 years of age to those <55 years of age and county characteristics associated with the availability of an ophthalmologist. We classified counties as metropolitan, nonmetropolitan, or rural using the 2013 US Department of Agriculture Urban/Rural Continuum Code (RUCC). The RUCC is a 9-point system that categorizes counties by degree of urbanization, population, and proximity to metropolitan areas; RUCC scores of 1-3 designate a metropolitan county, 4-7 a nonmetropolitan county, and 8 to 9 a rural county. We also collected county-level characteristics including the proportion of females, white non-Hispanic individuals, persons ≥65 years of age, persons >25 years of age who completed 4 years of college, persons in poverty, and persons 18-64 years of age without health insurance, as well as per capita income and total number of hospitals, rural referral centers, primary care physicians, and advanced practice registered nurses (APRNs). Supplement 1 describes the sources of these county-level data (supplemental material available at AJO.com ).
Statistical Analysis
We used simple linear regressions to determine the association between provider density and year for ophthalmologists (1995-2017) and optometrists (1990-2017). Simple linear regression was also used to identify if the ratio of older to younger ophthalmologists was significantly associated with time. χ 2 tests were used to compare the proportions of counties that lacked an ophthalmologist or optometrist and the proportion of the ophthalmologist workforce that was <55 years of age between the different county types. We conducted univariate and multivariable logistic regressions to identify county characteristics associated with the presence of ≥1 ophthalmologist in the county in 2017. A 2-sided P value < .05 was considered statistically significant. Data analysis, statistical analysis, and figures were generated with Microsoft Excel for Mac 2011 (v 14.4.7; Microsoft, Redmond, Washington, USA), R software (v 13.1.0; R Foundation for Statistical Computing, Vienna, Austria), and GraphPad Prism software (v 8; GraphPad Software, San Diego, California, USA).
Results
Ophthalmologist Density Over Time
In 2017, there were 18,512 ophthalmologists in the United States, corresponding to a mean national density of 5.68 ophthalmologists per 100,000 individuals. Rural counties had a mean density of 0.58 ophthalmologists per 100,000 individuals, which was lower than the 2.19 and 6.29 ophthalmologists per 100,000 individuals found in nonmetropolitan and metropolitan counties, respectively. Ophthalmologist densities by individual county are shown in Figure 1 , A. The majority of counties lacked an ophthalmologist (60.5%). The proportion of rural counties that lacked an ophthalmologist (97.4%) was significantly greater than the proportions of nonmetropolitan (67.0%; P < .001) and metropolitan counties (35.3%; P < .001) with 0 ophthalmologists.
From 1995 to 2017, the national ophthalmologist density significantly decreased from 6.30 to 5.68 ophthalmologists per 100,000 individuals, corresponding to a loss of 0.033 ophthalmologists per 100,000 individuals each year ( P < .001; Figure 2 , A). There was a mean decrease in the total ophthalmologist density by 0.44% per year, and a mean annual decline in density of 0.47% and 1.12% in metropolitan and nonmetropolitan counties, respectively. However, rural counties experienced a mean annual increase in ophthalmologist density by 2.26%, with an upward trend beginning in 2014.
Age of Ophthalmology Workforce Over Time
In 2017, the total number of ophthalmologists <55 years of age was 10,353 (54.8%). Metropolitan counties had a significantly younger workforce, as 55.5% of ophthalmologists in metropolitan areas were younger compared with 43.0% in nonmetropolitan areas ( P < .001) and 34.5% in rural areas ( P = .04). From 1995 to 2017, the overall ratio of older to younger ophthalmologists significantly increased from 0.37 to 0.82 ( P < .001; Figure 3 ). The greatest increase in the age ratio occurred in rural counties (from 0.29 to 1.90), followed by nonmetropolitan (0.37 to 1.32) and metropolitan counties (0.37 to 0.80). Rural counties had the greatest percent increase in older practitioners, with a 375.00% increase from 1995 to 2017, followed by metropolitan and nonmetropolitan counties, which increased by 86.09% and 70.72%, respectively. Concurrently, the number of younger ophthalmologists decreased by 28.57%, 52.49%, and 13.68% in rural, nonmetropolitan, and metropolitan counties, respectively.
Optometrist Density Over Time
In 2017, there were 52,625 optometrists nationwide, corresponding to a density of 16.16 providers per 100,000 individuals. Optometrist densities by county are shown in Figure 1 , B. Approximately a quarter of counties (23.3%) had 0 optometrists. Similar to the geographic distribution of ophthalmologists, optometrist density was lower in rural areas (6.77) compared with nonmetropolitan (15.84) and metropolitan areas (16.36 per 100,000 individuals). There was an overall significant increase in optometrist density between 1990 and 2017, from 11.06 to 16.16 providers per 100,000 individuals, with an estimated annual increase of 0.21 optometrists per 100,000 individuals per year ( P = .002; Figure 2 , B). The mean annual optometrist growth rate was lower in rural areas (1.04%) compared with nonmetropolitan (1.64%) and metropolitan areas (1.71%). When comparing the optometrist and ophthalmologist workforces over years for which data were available for both specialties, the ratio of optometrists to ophthalmologists increased from 2.46 to 2.84 between 2010 and 2017, representing a 15.6% increase.
County Factors Associated with the Presence of an Ophthalmologist
Univariate analysis revealed that counties with a greater percentage of females and individuals who had completed 4 years of college, or a lower percentage of white individuals and individuals ≥65 years of age were more likely to have ≥1 ophthalmologist ( Table ). In addition, counties with a higher per capita income and a lower proportion of individuals in poverty or without health insurance were more likely to have an ophthalmologist. Counties that had a greater number of hospitals, rural referral centers, primary care physicians, APRNs, and optometrists were also more likely to have ≥1 ophthalmologist. Lastly, the degree of urbanization of a county, as measured by the RUCC, was significantly associated with the presence of an ophthalmologist.
| County Variable | Univariate Model OR (95% CI) | P Value | Multivariable Model OR (95% CI) | P Value |
|---|---|---|---|---|
| Demographics | ||||
| Percent female | 1.45 (1.38-1.53) | <.001 | 1.08 (1.00-1.16) | .051 |
| Percent white, non-Hispanic | 0.99 (0.98-0.99) | <.001 | 0.99 (0.98-1.00) | .055 |
| Percent ≥65 years of age | 0.85 (0.84-0.87) | <.001 | 0.98 (0.94-1.02) | .25 |
| Percent persons >25 years of age with 4 years of college | 1.23 (1.21-1.25) | <.001 | 1.08 (1.04-1.13) | <.001 a |
| Economic | ||||
| Per capita income (dollars) | 1.00 (1.00-1.00) | <.001 | 1.00 (1.00-1.00) | .84 |
| Percent persons in poverty | 0.94 (0.93-0.95) | <.001 | 1.02 (0.99-1.05) | .30 |
| Percent persons 18-64 years of age without health insurance | 0.93 (0.92-0.94) | <.001 | 0.97 (0.94-0.99) | .019 a |
| Health care infrastructure | ||||
| No. of hospitals | 4.25 (3.76-4.83) | <.001 | 1.23 (1.00-1.50) | .045 a |
| No. of rural referral centers | 20.59 (11.96-39.17) | <.001 | 3.18 (1.57-6.95) | .002 a |
| No. of primary care physicians | 1.16 (1.14-1.17) | <.001 | 1.09 (1.07-1.11) | <.001 a |
| No. of APRNs | 1.10 (1.09-1.11) | <.001 | 1.04 (1.02-1.05) | <.001 a |
| No. of optometrists | 1.42 (1.38-1.47) | <.001 | 0.99 (0.96-1.03) | .67 |
| Degree of urbanization | ||||
| Rural/urban continuum code (1 = urban, 9 = rural) | 0.62 (0.60-0.64) | <.001 | 0.99 (0.93-1.06) | .84 |
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