EyeWorld Journal Club review: “Geographical barriers to surgical treatment for cataract among California Medicare beneficiaries”

ASCRS News: EyeWorld Journal Club
Summer 2026

by Harold Dorsey, MD, Ayush Parikh, MD, Gavin Li, MD, Mass Eye and Ear Ophthalmology Residents, Jennifer Lindsey, MD, MBA, Residency Program Director

Cataract is the most common reversible cause of vision impairment in the U.S. and accounts for approximately 60% of Medicare vision-related costs.¹ By 2050, the number of individuals affected by cataracts in the U.S. is projected to double to nearly 50 million.² While cataract surgery is a highly effective intervention, studies show that factors such as race, income, and rural residency create unique barriers to accessing care. Consequently, marginalized populations exhibit lower utilization of eyecare services and have a higher likelihood of undergoing complex cataract surgery. 

California, the most populous state, has a substantial rural population estimated at 2.3 million individuals. Although previous group-level studies suggest decreased access to cataract surgery in rural areas, the individual-level association between geographic factors and surgical treatment has not been studied. This study aims to compare travel distance and time for cataract surgery among rural versus non-rural California Medicare beneficiaries and to evaluate whether these geographic barriers are associated with the likelihood of receiving surgery, particularly examining differences across racial and ethnic groups.

Methods

A cross-sectional study was conducted using the 2017 California Medicare Master Beneficiary Summary File and Part B Carrier Claim files. Eligible beneficiaries were 65 years or older, resided in California, had active Medicare Part A and B coverage, and had an ICD-10-CM diagnosis code for cataract. The main variables of interest that were evaluated included: 1) rural versus non-rural residence, 2) estimated patient-to-cataract surgery provider distance and travel time, and 3) occurrence of cataract surgery. Covariates included age, sex, race and ethnicity, and systemic disease burden estimated by Charlson Comorbidity Index (CCI) score.

Beneficiary residence ZIP codes were categorized as rural or non-rural using Health Resources & Services Administration’s 2010 List of Rural Counties and Designated Eligible Census Tracts in Metropolitan Counties.³ Travel distance (miles) and travel time (hours) between the patient’s and the cataract surgery provider’s ZIP code centroids were calculated using ArcGIS Pro spatial analysis. The occurrence of cataract surgery was identified via CPT billing codes. Statistical analyses were performed using SAS version 9.4. Linear regression models were used to assess the association between rural residence and travel distance and time. Separate logistic regression models were utilized to estimate the adjusted odds of receiving cataract surgery based on travel distance and time, controlling for age, sex, race and ethnicity, and CCI scores.

To determine if the impact of travel barriers differed depending on a patient’s race or ethnicity, multivariable logistic regression models were used to test for a connection between travel distance and demographic groups (factoring in age, sex, CCI, and rural residency). If the interaction term between travel distance and race/ethnicity was statistically significant, separate logistic regression models were run for each racial and ethnic group to assess how travel distance affected that specific group’s likelihood of receiving surgery. 

Results

There were 445,164 Californian beneficiaries 65 years or older with cataracts who met this study’s inclusion criteria, and 93,460 (21.0%) received cataract surgery. Of those who underwent cataract surgery, 61,069 (63.3%) were White, 3,013 (3.2%) were Black, 11,966 (12.8%) were Asian, 13,946 (14.9%) were Hispanic/Latino, and 3,466 (3.7%) were Other. Of the beneficiaries who received cataract surgery, 27,587 (29.5%) met the rural residency designation. Among the beneficiaries with cataracts, there were statistically significant differences in age (P<0.0001), race and ethnicity (P<0.0001), sex (P=0.03), and CCI score (P<0.0001) between those who did and did not receive cataract surgery.

Even when adjusted for age, sex, CCI, race, and ethnicity, linear regression models demonstrated statistically significant differences in distance (9.7 [95% CI: 9.3–10.2] additional miles) and time (0.16 [95% CI: 0.15–0.17] additional hours) for rural versus non-rural beneficiaries when traveling for cataract surgery. When controlling for rural versus non-rural residence among beneficiaries with cataracts, each additional 100 miles of travel distance was associated with a 14% decreased adjusted odds of cataract surgery (adjusted odds ratio [aOR]: 0.86, 95% CI: 0.84–0.87), while each additional hour of travel time was associated with 6% decreased adjusted odds of cataract surgery (aOR: 0.94, 95% CI: 0.93–0.95). 

Stratification by race and ethnicity revealed a statistically significant interaction between travel distance and the adjusted odds of cataract surgery (P<0.0001). For every additional 100 miles of travel distance to cataract surgery, the adjusted odds of undergoing cataract surgery decreased by 62% in Black beneficiaries (aOR: 0.38 [95% CI: 0.31–0.45]), 33% in Hispanic/Latino beneficiaries (aOR: 0.67 [95% CI: 0.63–0.72]), 19% in Asian beneficiaries (aOR: 0.81, [95% CI: 0.76–0.87]), and 8% in White beneficiaries (aOR: 0.92, [95% CI: 0.90–0.94]).

Discussion

Geographic barriers to healthcare decrease utilization, raise costs, and increase morbidity for patients, especially for those in need of cataract surgery. Prior group-level research has explored this association but cannot fully ascertain why and for whom disparities may exist. In this cross-sectional study using a 2017 California Medicare claims data set, Murillo et al. found significant geographic barriers to cataract surgery at the individual patient level, which were further exacerbated when stratifying results by race and ethnicity. 

After adjusting for age, sex, CCI, race, and ethnicity, the study found that rural residents traveled significantly more than non-rural residents, on average an additional 9.7 miles and 9.6 extra minutes. Importantly, the authors also found that every additional 100 miles of travel was associated with 14% decreased odds of receiving cataract surgery (aOR 0.86, 95% CI 0.84–0.87) and that every additional hour decreased odds by 6% (aOR 0.94, 95% CI 0.93–0.95). These results demonstrate that rural Californians face greater travel burdens for cataract surgery, and increased travel is independently associated with lower likelihood of undergoing surgery. The authors infer that this may be due to scarcity of ophthalmologists in rural areas, which is supported by a separate study that found that only 9.1% of cataract surgeons are located in non-metropolitan areas. Notably, undergoing cataract surgery has been shown to reduce morbidity and mortality, such as rate of hip fractures, motor vehicle accidents, dementia, and depression.^4–7 Delay in undergoing cataract surgery may thus have significant implications for systemic health and well-being.

In the analysis of effect modification of this relationship between geography and cataract surgery by race/ethnicity, the authors found that Black and Hispanic/Latino individuals were disproportionately affected by geographic barriers. For every 100 additional miles of travel, odds of surgery decreased by 33% for Hispanic/Latino patients and 62% for Black patients. Within this context, the authors highlight a critical need to analyze and subsequently address individual and structural level social determinants of health, such as better distribution of ophthalmologists, greater investment in minority communities, and creation of safety net programs that ease transportation barriers.

Key limitations of this study include the fact that claims data does not capture other unmeasured confounders such as actual clinical need for surgery. For example, patients with only mild and asymptomatic cataracts would not meet surgical criteria, which could partially explain rural-urban differences in surgery rates independent of access barriers. Claims data also cannot capture patient preference or supplemental coverage. For example, approximately one-third of 2017 Medicare beneficiaries were enrolled in Medicare Advantage, whose claims are not captured in this dataset.⁸ Additionally, cross-sectional observational studies cannot prove causal relationships, although this study adds onto the prior body of work that demonstrates similar findings at group or population levels. Results may also not be generalizable beyond Medicare-aged populations or to patients with private insurance, although the vast majority of cataracts are sequelae of aging, and patients with non-Medicare insurance likely face similar geographic hurdles. This study was also restricted to analyzing a single-state Medicare population, although California is the most urban state in the U.S., in which 94.2% of the population resides within urban areas according to 2020 Census data.^9,10 While national level research would be of utility, the results of this study pose great implications for states or regions with greater proportions of rural residents. The strengths of this study include the utilization of a large and ethnically/racially diverse data set with individual data that allows for novel geospatial and effect modification analyses.

Conclusion

This study demonstrated that rural Californian beneficiaries traveled greater distances and spent more time traveling for cataract surgery, which can significantly reduce their odds of undergoing the procedure. Interestingly, the association between increased travel distance and decreased odds of cataract surgery was most pronounced in Black and Hispanic/Latino beneficiaries, suggesting that geographic barriers accentuate gaps in surgical access along racial and ethnic lines. The authors propose numerous solutions to mitigate these issues, including subsidizing travel, expanding teleophthalmology, investing in targeted community outreach, and increasing ophthalmology resources in under- resourced communities. They also suggest the need for further studies analyzing factors such as geographic residence, socioeconomic status, race, and ethnicity, and their effects on access to ophthalmic surgical care. 

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Geographical barriers to surgical treatment for cataract among California Medicare beneficiaries

Murillo K, et al. J Cataract Refract Surg. 2026;52:544–550. 

• Purpose: To examine geographic factors associated with the likelihood of receiving cataract surgery. 
• Setting: Administrative claims data from 2017 California Medicare Database. 
• Design: Cross-sectional. 
• Methods: Beneficiaries were included if they were 65 years or older, had a valid postal code, active coverage with Medicare parts A and B, and cataract diagnosis defined by International Classification of Diseases, 10th Revision, Clinic Modification (ICD-10-CM) codes. Cataract surgery was defined using billing codes. The association between rural residence and distance and time traveled for cataract surgery was assessed using linear regression models. The odds of receiving cataract surgery were estimated using logistic regression models. 
• Results: Among 445,164 beneficiaries with cataract, 127,314 (28.6%) reported rural residency. Rural residence was associated with increased travel time and distance for cataract surgery (+0.16 hours [95% confidence interval (CI): 0.15–0.17]; +9.7 miles [95% CI 9.3–10.2]). For every additional 100 miles traveled, odds of cataract surgery decreased by 14% (adjusted odds ratio (aOR): 0.86; 95% CI: 0.84–0.87). Stratified analysis demonstrated that Black beneficiaries had the greatest reduced odds of cataract surgery per each 100 additional miles traveled (aOR: 0.38; 95% CI: 0.31–0.45), followed by Hispanic/Latino beneficiaries (aOR: 0.67; 95% CI: 0.63–0.72). 
• Conclusions: Beneficiaries living in rural California had increased travel distance and time for cataract surgery. Black beneficiaries had the strongest association between increased travel distance and decreased odds of cataract surgery. These findings suggest possible disparities in surgical treatment for cataract among rural populations. Further studies are needed to better understand and address geographic disparities to eyecare.

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References

1. Ellwein LB, Urato CJ. Use of eye care and associated charges among the Medicare population: 1991–1998. Arch Ophthalmol. 2002;120:804–811. 
2. National Eye Institute. NEI charts a clearer future for cataract prevention and treatment. Published June 29, 2017; accessed December 2, 2022. www.nei.nih.gov/about/news-and-events/news/nei-charts-clearer-future-cataract-prevention-and-treatment.
3. Health Resources & Services Administration. List of Rural Counties and Designated Eligible Census Tracts in Metropolitan Counties. Health Resources & Services Administration; 2018.
4. Foss AJE, et al. Falls and health status in elderly women following second eye cataract surgery: a randomised controlled trial. Age Ageing. 2006;35:66–71.
5. Owsley C, et al. Impact of cataract surgery on motor vehicle crash involvement by older adults. JAMA. 2002;288:841–849.
6. McGwin G Jr, et al. The impact of cataract surgery on depression among older adults. Ophthalmic Epidemiol. 2003;10:303–313.
7. Lee CS, et al. Association between cataract extraction and development of dementia. JAMA Intern Med. 2022;182:134–141.
8. Jacobson G, et al. Medicare Advantage 2017 Spotlight: Enrollment Market Update. Kaiser Family Foundation. Published 2017. www.kff.org/medicare/medicare-advantage-2017-spotlight-enrollment-market-update/.
9. Johnson H, Cuellar Mejia M. Rural California. Public Policy Institute of California. March 2023. www.ppic.org/publication/rural-california/.
10. US Census Bureau. Nation’s Urban and Rural Populations Shift Following 2020 Census. Published December 29, 2022. www.census.gov/newsroom/press-releases/2022/urban-rural-populations.html.

Contact 

Lindsey: jllindsey@meei.harvard.edu