Purpose: The present study was designed to determine the extent that horizontal inequity was realized regarding eye care utilization in a middle-aged population as well as factors affecting this equity.

Methods: Data were obtained from a population-based study (Shahroud Eye Cohort Study) in 2009 that included 5190 participants from 40 to 64 years of age. Horizontal inequity was determined based on the following variables: (i) economic status, (ii) eye care service needs, (iii) non-need variables, and (iv) eye care utilization (visiting an ophthalmologist or optometrist). Decomposition analysis of the concentration index based on a nonlinear model and indirect standardization was used to ascertain the contribution of each factor in inequity of eye care utilization.

Results: After adjusting for need variables, the results of our study demonstrated that horizontal inequity in eye care utilization in a middle-aged Iranian population remained positive and significant (horizontal inequity: 0.19; 95% confidence interval: 0.17-0.23) indicating that use of services was focused among participants with a better financial situation. Furthermore, decomposition analysis demonstrated that educational level and economic status had the greatest contribution (54.1% and 41.1%, respectively) in comparison to other variables.

Conclusion: This study demonstrated that horizontal inequity exists in eye care utilization among the middle-aged Iranian population.