Study to establish visual acuity norms with Teller Acuity Cards II for infants from southern China

Objectives To establish the norms of binocular and monocular acuity and interocular acuity differences for southern Chinese infants and compare these norms with the results for northern Chinese infants. Methods A prospective, comparative, and noninterventional study was conducted from January to August 2018. Teller Acuity Cards II were used to determine the binocular and monocular acuity of infants. The tolerance intervals and limits with a stated proportion and probability were used to evaluate the norms of binocular and monocular acuity and interocular acuity differences. An unpaired t-test was used to compare the obtained norms with the reported northern Chinese norms. Results The tolerance intervals of binocular acuity (mean acuity of 3.73, 7.35, and 12.01 cpd, respectively, at 12, 24, and 36 months), monocular acuity (mean acuity of 2.88, 6.91, and 10.75 cpd, respectively, at 12, 24, and 36 months), and interocular acuity differences (mean difference of 0.92, 2.89, and 3.99 cpd, respectively, at 12, 24, and 36 months) were obtained, exhibiting an increasing trend with age. The binocular visual acuity norms of southern Chinese infants were significantly lower than those in northern China (4.37 vs. 6.9 cpd at 8 months and 7.35 vs. 26 cpd at 24 months) (P = 0.011). Conclusions Northern and southern Chinese infants exhibited distinct acuity norms and visual development patterns. The establishment of population-specific visual acuity norms is necessary for current populations of infants from different regions.