Normative visual acuity in Chinese preschoolers aged 36 to <48 months as measured with the linear HOTV chart: the Yuhuatai Pediatric Eye Disease Study

OBJECTIVES: To document population-based normative data for uncorrected visual acuity (UCVA) in Chinese preschoolers aged 36 to <48 months without any sight-affecting abnormalities and to evaluate its effectiveness for vision referral. METHODS: In a population-based cohort of children in the Yuhuatai Pediatric Eye Disease Study, UCVA was measured by using the linear HOTV chart, followed by other ocular examinations. Reference population was defined as children without ophthalmic abnormalities or refractive error. Normative UCVA was obtained from the reference population. The UCVA referral cut-off was defined as the lowest fifth percentile of the normative distribution of UCVA. RESULTS: The analysis cohort consisted of 1606 Chinese preschoolers aged 36 to <48 months. Among them, a total of 791 children were included in the reference population. The 5th, 50th and 95th percentiles of the UCVA distribution in the reference population were 20/40, 20/32 and 20/25, respectively. UCVA improved with increasing age (p<0.0001), but worsen if prematurity was presented (p=0.041). Using the fifth percentile, UCVA cut-off from the reference population generated referral rates of 26.9% in the general population, and detected more than 86% of amblyopia cases. CONCLUSIONS: We propose that UCVA no better than 20/40 measured by linear HOTV chart should be a referral cut-off for Chinese preschoolers aged 36 to <48 months. Most amblyopia cases can be identified with this age-specific and chart-specific UCVA cut-off.