Prevalence, Predictors, and Persistence of Inadequate Spectacle Correction in Vietnamese Schoolchildren

Background Inadequate spectacle correction limits the benefit of school vision screening, yet most evidence addresses only whether a child owns glasses rather than whether those glasses work. This study examined the prevalence, predictors, and persistence of inadequate spectacle correction among schoolchildren in three Vietnamese cities. Methods We analyzed annual vision screening records of students from a private school network in Ha Noi, Ho Chi Minh City, and Hai Phong, 2021 to 2024. Inadequate correction was defined as visual acuity below the age-appropriate threshold despite current glasses. A population-averaged modified-Poisson regression with robust standard errors, clustered by child, estimated adjusted prevalence ratios (aPR) for city, age, sex, and calendar year. Children linked across consecutive years allowed persistence analysis. Results Among 39,697 spectacle-wearing examinations, 30,936 (77.9%) were inadequately corrected, ranging from 64.8% (95%CI= 63.9, 65.8) in Ho Chi Minh City to 96.7% (96.0, 97.3) in Hai Phong. After adjustment, prevalence was lower in Ho Chi Minh City (aPR= 0.76; 95%CI= 0.75, 0.78; p<0.001) and higher in Hai Phong (aPR= 1.25; 95%CI= 1.23, 1.26; p<0.001) relative to Hanoi, and fell with age (aPR= 0.97 per year; 95%CI= 0.96, 0.97; p<0.001). Among 9,285 linked year pairs from 8,341 children, 85.3% (84.4, 86.1) of initially inadequately corrected children remained so the following year. Conclusions Most spectacle-wearing children in this Vietnamese cohort were inadequately corrected, with wide geographic variation and high persistence. School vision programs need mechanisms to verify correction adequacy after glasses are dispensed, not only to detect refractive error.