Aims To document the difference between non-cycloplegic and cycloplegic refraction and explore its associated factors in Chinese young adults.
Methods A school-based study including 7971 undergraduates was conducted in Anyang, Henan Province, China. Cycloplegia was achieved with two drops of 1% cyclopentolate and 1 drop of Mydrin P (Tropicamide 0.5%, phenylephrine HCl 0.5%) with a 5 min interval. Non-cycloplegic and cycloplegic refractions were measured by an autorefractor. A paired-sample t-test and Spearman correlation analysis were used for analysis with data from only the right eyes included.
Results Of the 7971 students examined, 7793 (97.8%) with complete data were included, aging 20.2±1.5 years. Male students accounted for 36.8%. Overall, there was a significant difference between non-cycloplegic and cycloplegic SE (spherical equivalent) of 0.83±0.81D (p<0.01). The difference was 1.80±1.11D, 1.26±0.93D and 0.69±0.69D for those with cycloplegic hyperopia, emmetropia and myopia, respectively (p<0.01 for all). Those with a hyperopic shift less than 0.25D and 0.5D accounted for 11.1% and 34.1%, respectively. A significant relationship was found between difference in SE and cycloplegic refraction (r=0.33, b=0.11, p<0.01). Without cycloplegia, prevalence of hyperopia and emmetropia would be underestimated by 6.2% (1.0% vs 7.2%) and 5.7% (3.8% vs 9.5%), respectively, with prevalence of myopia and high myopia overestimated by 12.1% (95.3% vs 83.2%) and 6.1% (17.2% vs 11.1%).
Conclusion Lack of cycloplegia will lead to significant misclassification of myopia, emmetropia and hyperopia in Chinese young adults. Cycloplegia is therefore essential for this age-group in epidemiological studies.
- cycloplegic refraction
- young adults
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Contributors NLW had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: YYS, SML, IGM, NLW. Acquisition, analysis or interpretation of data: YYS, SFW, JPH, XHY, KC, CXL, JLD, JYG, HL. Drafting of the manuscript: YYS. Critical revision of the manuscript for important intellectual content: All authors. Study supervision: NLW.
Funding This study was supported by the Integration, translation and development on Ophthalmic technology (Jingyiyan 2016-5), the Capital Health Research and Development of Special (2016-4-2056) and the Major International (Regional) Joint Research Project of the National Natural Science Foundation of China (81120108007).
Competing interests None declared.
Patient consent Not required.
Ethics approval Institutional Review Board of Beijing Tongren Hospital, Capital Medical University.
Provenance and peer review Not commissioned; externally peer reviewed.