Objective. To investigate the prevalence of refractive errors among school children in Suining City, Sichuan Province, and to provide a scientific basis for prevention and control of myopia. Methods. This was a school-based cross-sectional study. Children aged 6-15 years were selected from kindergartens, primary schools, and middle schools in the urban setting of Suining City. The children underwent ocular examination including measurement of uncorrected visual acuity (UCVA), visual acuity when wearing glasses, and noncycloplegic autorefractometry. Results. Of the 1200 eligible students, 1138 children (94.8%), 553 of them girls (47.4%), participated. The mean age was 10.64 ± 2.89 years. The prevalence of myopia, hyperopia, astigmatism, and emmetropia was 59.1% (95% confidence interval (CI): 57.6, 60.5), 5.0% (95% CI: 4.7, 6.1), 38.4% (95% CI: 55.5, 58.5), and 25% (95% CI: 23.7, 26.2), respectively. In univariate analysis, the prevalence of myopia was correlated with age, female gender, and learning stage. The prevalence of hyperopia and astigmatism was correlated with age and learning stage. The prevalence of mild myopia, moderate myopia, and high myopia in the 1138 students was 17.7%, 41.4%, and 3.3%, respectively. The prevalence of mild, moderate, and high myopia all increased with age and learning stage. The prevalence of myopia differed by gender. The mean spherical equivalents of the right and left eyes were − 1.40 ± 1.99 diopters (D) and − 1.29 ± 1.93   D , respectively, and the median values were -0.75 D and -0.6 D, respectively. The mean spherical equivalent increased with age, learning stage, and female gender. Conclusions. The most common type of refractive error was myopia which was associated with higher age, female gender, and higher learning stage. This study provides new data and recommendations for myopia-control in school-aged children in Sichuan province.

Background:The aim of this study was to compare the effects of manipulating lighting levels versus manipulating the short wavelength contents of ambient lighting on refractive development in young rabbits. Methods: A total of 32 healthy 3-week-old rabbits were randomly assigned to one of four groups with 8 in each group. Normal blue at normal illuminance (control, NC) group and normal blue at high illuminance lighting (HI) group were exposed to light emitted by ordinary LED lamps with low content in the short wavelength range. High-blue at high illuminance(Simulating natural light, S-NL) group and high-blue at normal illuminance (High-blue, HB) group were exposed to the light with high content in the short wavelength range provided by ordinary LED and blue LED lamps. The approximate mean illuminance (in human lux) on the cage floor was (NC:341lux, HI:5057lux, HB:342lux, S-NL: 5051lux). Refractive error, axial dimensions and corneal curvature radius were assessed by retinoscopy, ultrasonography and keratometry, respectively. Average data of both eyes for each animal were compared across groups.Results: During the intervention, all animals had an emmetropization period. The refractive development of HI group was similar to S-NL group, both significantly slower than that of HB and NC group (p<0.001). While the decrease of group refraction in HB paralleled to the control group (p=0. 381). At the 12th week, the group refraction of S-NL(3.000±0.267D) was similar to HI (3.250±0.267D), more hyperopic than HB(2.219±0.281D) and NC (1.938±0.291D). The vitreous chamber depth of S-NL (7.421±0.168mm) was shorter than HB (7.785±0.230mm) and NC (7.825±0.313mm), similar to that of HI group(7.264±0.256mm). The other components were less effected by light conditions(p＞0.05). Conclusions: Extrapolated from rabbits, these findings suggest that high illuminances per se but not the rich in short wavelengths determine the inhibitory effect of ambient lighting on myopia after increasing time outdoors.

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