The effect of education level between PIR and myopia: An interaction and mediation analysis

BackgroundThe role of socioeconomic factors, particularly educational attainment, in the relationship between income and myopia remains unclear. As the poverty income ratio (PIR) reflects economic status, understanding its interaction with education on myopia prevalence is essential for informing public health and clinical strategies. MethodsThis cross-sectional study analyzed NHANES data (1999-2008) with 28,867 participants. Weighted multivariable logistic regression, generalized additive models, and mediation analysis were used to assess PIRs association with myopia and the mediating/moderating role of education. ResultsPIR was significantly associated with myopia prevalence (OR = 1.05, 95% CI: 1.02- 1.08), but the association varied by age, gender, and education.Age: PIR was positively associated with myopia in individuals <60 years, but not in those [&ge;]60.Gender: No significant association in males, while in females, PIR was positively linked to myopia (Right eye: OR = 1.05; Left eye: OR = 1.07).Education: In lower-education groups (Grade 9-11 and below), PIR and left-eye myopia showed a threshold effect at PIR = 2.9 (PIR < 2.9: OR = 0.92; PIR > 2.9: OR = 1.08). The right eye showed a similar but nonsignificant trend. In higher-education groups, PIR exhibited a linear association with left-eye myopia (OR = 1.08) and a nonlinear association with right-eye myopia, with risk increasing sharply at PIR = 4.44 (OR from 1.05 to 1.29). Education mediated 20% of PIRs effect on right-eye myopia and 24% on left-eye myopia. ConclusionEducation plays a crucial mediating and moderating role in the PIR-myopia relationship, with a stronger effect in the left eye. The findings suggest integrating socioeconomic and educational factors into myopia prevention strategies to identify high-risk populations.