The effect of health insurance coverage on medical care utilization and health outcomes: Evidence from Medicaid adult vision benefits.

Increasing the proportion of adults that have regular, comprehensive eye exams and reducing visual impairment due to uncorrected refractive error and other common eye health problems are federal health objectives. We examine the effect of vision insurance on eye care utilization and vision health outcomes by taking advantage of quasi-experimental variation in Medicaid coverage of adult vision care. Using a difference-in-difference-in-difference approach, we find that Medicaid beneficiaries with vision coverage are 4.4 percentage points (p<0.01) more likely to have seen an eye doctor in the past year, 5.3 percentage points (p<0.01) less likely to report needing but not purchasing eyeglasses or contacts due to cost, 2.0 percentage points (p<0.05) less likely to report difficulty seeing with usual vision correction, and 1.2 percentage points (p<0.01) less likely to have a functional limitation due to vision.