Study Finds Improved Visual Impairment Associated With Accessible Eye Care Clinicians

A cross-sectional study found that areas with a high number of eye care clinicians had a lower prevalence of vision impairment.

Geographic distribution of eye care clinicians was associated with better outcomes in visual impairment, according to new study findings published in JAMA Ophthalmology, with people in areas with less eye care clinicians reporting higher prevalence of visual impairment.

The study used data from the American Community Survey (ACS) from 2014 to 2018, the California Health and Human Services Open Data Portal, the American Academy of Ophthalmology (AAO) membership data, and the 2020 Blue Book of Optometrists to determine the number of ophthalmologists and optometrists per 100,000 residents and prevalence of visual impairment by county and Medical Service Study Area (MSSA).

For the stidy, vision difficulty was defined as “blind or having serious difficulty seeing, even when wearing glasses.” Potential confounders included age, sex, race and ethnicity, education, income, lack of health insurance, and residence type

Fifty-eight counties and 542 MSSAs in California were evaluated in this study, which covered 30,068,581 adults 18 years and older. Most sutdy participants identified as Latino (38.9%) or White (37.5%), and 49.3% identified as male. There were 87.6% of participants who lived in an urban area, with 10.0% with no health insurance and 23.1% earning 150% or less of the federal poverty level (FPL).

Four counties had no eye care clinicians (Alpine, Mariposa, Inyo, and Sierra), and 3 counties had more than 30 eye care clinicians per 100,000 residents (San Francisco, Mono, and San Luis Obispo). The 3 counties with the highest prevalence of visual impairment per 100,000 residents were Tehama (5127.94), Calaveras (4855.73), and Merced (4676.09); the 3 counties with the lowest prevalence were Sierra (1096.67), Marin (1647.15), and San Mateo (1705.68).

When eye care clinicians increased, prevalence of visual impairment decreased at the MSSA level (r, –0.21; 95% CI, ­–0.30 to –0.12) and county level (r, –0.40; 95% CI, –0.59 to –0.15). The mean (SD) prevalence of visual impairment was 3.170.53 (1331.78) per 100,000 residents in MSSAs with optometrists only and 2365.07 (926.31) per 100,000 residents in MSSAs with ophthalmologists and optometrists.

FPL had a higher correlation with the rate of visual impairment (r, 0.49; 95% CI, 0.43-0.55) than lack of health insurance (r, 0.21; 95% CI, 0.13-0.29). Increased age, male sex, and FPL were significantly associated with increased visual impairment in adjusted analyses.

There were some limitations to this study. MSSAs are defined in relation to primary care clinicians, not eye care clinicians. Data for ophthalmologists were from 2018, and data for optometrists were from 2020 whereas visual impairment was calculated in surveys from 2014 to 2018, with the different years potentially not reflecting the exact association between eye care clinicians and visual impairment.

There is also potential for uncontrolled confounding by unmeasured factors and potential misclassification of geographic area of practice of eye care clinicians. AAO membership data do not include nonmember ophthalmologists, so there also is a possibility of ophthalmologists present in areas recorded as having none.

The researchers concluded that this study found associations between increased number of eye care clinicians and decreased prevalence of visual impairment after adjusting for demographic and socioeconomic factors.

“Further studies are needed to investigate reasons for these associations as well as strategies to improve access to eye care and reduce visual impairment in the population and determine whether these results can be generalized to areas outside of California,” the authors wrote.


Wang KM, Tseng VL, Liu X, et al. Association between geographic distribution of eye care clinicians and visual impairment in California. JAMA Ophthalmol. Published online May 5, 2022. doi:10.1001/jamaophthalmol.2022.1001