Title: Factors Associated with Amblyopia Among the Elderly in the CA Medicare Population

Author: Ricardo Oregon Guzman

Area of Concentration (Petal): Health Justice & Advocacy

Specialty: Ophthalmology

Keywords: Amblyopia, Social Vulnerability, Sociodemographic Factors, Systemic Factors

Background: Amblyopia is a leading cause of vision loss in children, most commonly associated with strabismus, refractive errors, and other intraocular pathology.1,2 Early screening for refractive error and strabismus significantly improves amblyopia prevention and treatment outcomes.2,3 While strategies to mitigate amblyopia in children are well understood, residual amblyopia in adults may be associated with social unreliability.

Objective: To explore the association between sociodemographic and systemic factors and amblyopia prevalence in the 2019 California (CA) Medicare population.

Methods: A study was conducted in 2019 CA Medicare beneficiaries aged 65+, residing in CA, enrolled in Medicare Parts A and B, with at least one Part B claim, and valid zip codes for Social Vulnerability Index (SVI) values. The outcome was amblyopia defined by a Part B claim with an ICD-10 code. Exposures were age, sex, race and ethnicity, systemic disease burden measured by Charlson Comorbidity Index (CCI) score, and social vulnerability measured by Centers for Disease Control and Prevention SVI quartiles. Multivariable logistic regression assessed factors associated with amblyopia prevalence. Univariable comparisons examined prevalence of refractive error (myopia, hyperopia, astigmatism, and any refractive error) and strabismus in beneficiaries with vs. without amblyopia.

Results: The study sample included 2,649,107 CA Medicare. Beneficiaries with a diagnosis of amblyopia were 8,460 (0.3%), with the largest proportions aged 70-74 2,334 (27.6%), female 4,920 (58.2%), Non-Hispanic White 6,432 (76.0%), CCI score of 1-2 3,013 (35.6%), and in SVI Q1 2,610 (30.9%). In beneficiaries with vs. without amblyopia, there was a statistically significant higher prevalence of all types of refractive error and of strabismus (p < .0001 for all). In adjusted logistic regression models, factors associated with increased odds of amblyopia were older age (age 75-79 vs. 65-69 adjusted odds ratio [aOR]: 1.42, 95% CI: 1.33-1.51), female sex (aOR: 1.10, 95% CI: 1.05-1.15), and higher CCI score (CCI score 5+ versus 0 aOR: 1.30, 95% CI: 1.21-1.40). Factors associated with decreased odds of amblyopia included racial and ethnic minoritization (Black vs. White aOR: 0.51, 95% CI: 0.44-0.59) and higher SVI quartile (Q4 vs. Q1 aOR: 0.67, 95% CI: 0.62-0.71).

Conclusions: In the 2019 CA Medicare population, older age, female sex, and higher systemic disease burden were associated with increased likelihood of amblyopia, while those racially and ethnically minoritized and with higher social vulnerability had decreased likelihood. Further research is needed to examine socioeconomic resources and strategies for elderly individuals with amblyopia.

References:

1. Kaur S, Sharda S, Aggarwal H, Dadeya S. Comprehensive review of amblyopia: Types and management. Indian J Ophthalmol. 2023;71(7):2677-2686. doi:10.4103/IJO.IJO_338_23

2. Wallace DK, Repka MX, Lee KA, et al. Amblyopia Preferred Practice Pattern®. Ophthalmology. 2018;125(1):P105-P142. doi:10.1016/j.ophtha.2017.10.008

3. Holmes JM, Levi DM. Treatment of amblyopia as a function of age. Vis Neurosci. 2018;35:E015. doi:10.1017/S095252381700022