The Association of Scope of Practice Expansion with Changes in Optometry Workforce Density

Abstract Importance: Access to eye care is increasingly constrained by declining ophthalmologist workforce density, particularly in rural areas, while optometrist workforce is projected to exceed demand. Numerous state legislatures have expanded optometrist scope of practice (SOP), but the workforce effects of these policies have not been evaluated.. Objective: To evaluate changes in optometrist and ophthalmologist workforce density following state-level expansion of optometrist scope of practice. Design: This retrospective ecological study analyzed workforce density across 50 states and the District of Columbia. Between 2008 - 2019, nine states expanded SOPs for optometrists. We used interrupted time-series regression to estimate associations between these policy changes and provider density from 2010-2021, adjusting for covariates. Setting: Population-based analysis of all 50 US states and the District of Columbia, 2010 - 2021. Participants: State-level workforce data were derived from Bureau of Labor Statistics and US Census data (optometrists) and the American Medical Association Physician Masterfile (ophthalmologists). Socioeconomic covariates were obtained from the American Community Survey. Exposure: State-level legislative expansion of optometrist SOPs to allow injections beyond anti-anaphylaxis treatment, lesion removal, and/or laser procedures. SOP changes were identified through systematic review of legislative and regulatory records. Main Outcomes and Measures: Annual change in optometrist and ophthalmologist workforce density (providers per 100,000 population) following SOP expansion, adjusted for age, income, rates of vision difficulty, diabetes, poverty, and uninsured status. Results: Nine states met inclusion criteria for SOP expansion between 2008 and 2019. Analysis of national data showed that among all 50 US states and the District of Columbia, SOP expansion was associated with a non-significant change in optometrist density (-0.65 per 100,000; 95% CI, -1.87 to 0.57) and ophthalmologist density (+0.09; 95% CI, -0.10 to 0.28). Results were consistent in the 9-state subgroup (optometrists: -0.60, 95% CI -2.90 to 1.70; ophthalmologists: +0.02, 95% CI -0.13 to 0.18). Conclusions and Relevance: Our population-level data suggest that, in the US, state legislation expanding optometrist scope of practice has not been associated with increased workforce density. As numerous state legislatures continue to consider such policies, these findings can inform efforts to balance access to eye care with patient safety.