Myopia is a relatively prevalent and increasing public health concern, particularly in East Asia, where it has already reached a pandemic level.¹ An estimated 2.5 billion people will be affected by myopia in 2020.² The prevalence has been reported to be 80% or higher in the young adult population in certain Asian countries or areas, such as Singapore, Hong Kong, and Taiwan.^3-5 Similarly, in the United States, the prevalence of myopia is 20% to 50% among the population older than 12 years.⁶ This silent epidemic should not be ignored.⁷ The worldwide prevalence of myopia and high myopia is estimated to increase substantially, affecting nearly 5 billion and 1 billion people, respectively, by 2050.⁸ In addition, the cost of uncorrected refractive error is a very real existing problem, affecting as many as 88% of children with myopia, and thus, the implications of increasing myopia prevalence worldwide are significant.^8,9 Apart from the substantial socioeconomic cost, severe sight-threatening complications associated with high myopia substantially compromise quality of life.¹⁰ An excellent review by Flitcroft^11(p622) clearly demonstrates that no safe threshold for myopic refractive errors exists, which suggests that no such thing as “physiological myopia” exists. A recent study¹² reported that axial lengths of 26 mm or greater and refractive errors of −6 diopters (D) or greater are significantly associated with an increased lifetime risk for visual impairment. Therefore, an effective treatment to slow or even stop myopia progression in young children is urgently needed. Researchers and clinicians have proposed approaches to treat myopia for many years. However, to date, no ideal approach has been identified as efficacious for the prevention and treatment of myopia with sufficient safety and clinical acceptability.¹³

Background: The prevalence of myopia among children in Chengdu is unknown. The aim of this study was to determine the prevalence of myopia in 3- to 14-year-old Chinese children in Chengdu. Methods: This study was a school-based cross-sectional study in children aged 3–14 years. Visual acuity (VA), spherical equivalent error (SER) with noncycloplegic autorefraction, axial length (AL) and corneal radius (CR) were measured. Results: A total of 19,455 children were recruited for this study. The prevalence of myopia was 38.1 %; the prevalence of low myopia was 26.6 %, that of moderate myopia was 9.8 %, and that of high myopia was 1.7 %. The prevalence of myopia and SER increased with age from 6 years old. The prevalence of myopia was higher, and the SER indicated more severe myopia in the girls than in the boys (40.1 % vs. 36.2 %, χ² = 30.67, d_f = 1, P < 0.001; -0.93 D ± 1.75 D vs. -0.84 D ± 1.74 D, t = 3.613, d_f=19,453, P < 0.001). The girls had a higher prevalence of myopia and myopic SER than did the boys aged 9 years and older (P < 0.05). Among the myopic children, the rates of uncorrected, undercorrected and fully corrected myopia were 54.8 %, 31.1 and 14.1 %, respectively. AL and AL/CR increased with age from 6 years old, but CR remained stable after 4 years old. The AL was longer, and the CR was flatter in the boys than in the girls aged 3 to 14 years old (P < 0.05). Conclusions: The prevalence of myopia, AL and AL/CR increased, and the SER became more myopic with age from 6 years old. The girls had a higher prevalence of myopia and myopic SER than did the boys, but the boys had a longer AL, flatter CR and higher AL/CR ratio than did the girls. The rate of uncorrected myopia was very high in the myopic children. More actions need to be taken to decrease the prevalence of myopia, especially uncorrected myopia in children.

Background: Virtual reality is being increasingly applied in vision therapy. However, the differences in effectiveness, optimal treatment cycle, and prognosis between virtual reality-based vision therapy and traditional therapies remain unknown. The purpose of this study was to compare the effectiveness of virtual reality-based vision therapy and office-based vergence/accommodative therapy in young adults with convergence insufficiency or accommodative dysfunction.Methods: The patients were randomly assigned to either the virtual reality-based vision therapy group or the office-based vergence/accommodative therapy group. The vision therapy lasted 12 weeks (1 h/week) in both groups. Binocular visual functions (vergence and accommodation) were measured and a subjective questionnaire-based assessment was performed at baseline and after 6 and 12 weeks of therapy.Results: In total, 33 patients with convergence insufficiency and 30 with accommodative dysfunction completed the study. After 12 weeks of treatment for convergence insufficiency, the Convergence Insufficiency Symptom Survey score (F_2,31 = 13.704, P < 0.001), near point of convergence (F_2,31 = 21.774,P < 0.001), positive fusional vergence (F_2,31 = 71.766,P < 0.001), and near horizontal phoria (F_2,31 = 16.482,P < 0.001) improved significantly in both groups. Moreover, the monocular accommodative amplitude (F_2,25 = 22.154,P < 0.001) and monocular accommodative facility (F_2,25 = 86.164,P < 0.001) improved significantly in both groups after 12 weeks of treatment. A statistically significant difference was observed in monocular accommodative facility (F_1,25 = 8.140,P = 0.009) between the two groups, but not in other vergence and accommodative functions (0.098 < P < 0.687).Conclusion: Virtual reality-based vision therapy significantly improved binocular vision functions and symptoms in patients with convergence insufficiency and accommodative dysfunction, thereby suggesting its effectiveness as a new optional or additional treatment for young adults with these conditions.Trial registration: This study was registered at the Chinese Clinical Trials Registry on 16/04/2019 (identifier:ChiCTR1900022556).