Atropine or Cyclopentolate to Diagnose Premyopia in Preschool Children.

Importance: Sufficient cycloplegia is essential for reliable refraction in preschool children. The choice of cycloplegic agent may affect refraction and diagnosis outcomes. Objective: To evaluate the objective refraction outcomes after cycloplegia in preschool children given either atropine or cyclopentolate. Design, Setting, and Participants: This was a post hoc analysis of the 2024 Preschool Children Refractive Development Pattern and Influencing Factors Study (PRDP-IFS), in which children were given atropine, and the 2013 to 2014 Elaborative Shanghai Childhood Ocular Refractive Development Study (E-SCORDS), in which children were given cyclopentolate. These were population-based studies. Eyes in each group were included via propensity score matching. Study data were analyzed from December 2024 to July 2025. Exposures: Cycloplegia induced by either 1% atropine (twice daily for 4 days with an additional dose on day 5) or 1% cyclopentolate (dual administration 5 minutes apart) eye drops. Main Outcomes and Measures: Difference between the noncycloplegic and cycloplegic spherical equivalent (DSE) and the prevalence of refractive states were compared in the atropine and cyclopentolate groups. Refractive states (moderate to high hyperopia, low hyperopia, premyopia, and myopia) were determined by cycloplegic spherical equivalent (SE) using an autorefractor. Results: A total of 1761 children and their 3048 eyes were included in this study. There were 773 children (1524 eyes) in the atropine group (mean [SD] age, 4.62 [0.92] years; 406 male [52.5%]) and 988 children (1524 eyes) in the cyclopentolate group (mean [SD] age, 4.62 [0.93] years; 530 male [53.6%]). There were a total of 1524 eyes in each group. The mean (SD) noncycloplegic SE was 0.30 (0.92) diopters (D) and 0.31 (0.76) D in the atropine and cyclopentolate groups, respectively (mean difference, -0.01 D; 95% CI, -0.07 to 0.05 D; P = .72). Mean (SD) DSE in the atropine group was 1.56 (0.72) D and in the cyclopentolate group was 0.97 (0.70) D. The mean difference in DSE between the 2 groups was 0.59 D (95% CI, 0.54-0.64 D; P < .001). The difference in the percentages of refractive states between the atropine and cycloplegic groups was as follows: moderate to high hyperopia (7.2% vs 2.7% = 4.5%; 95% CI, 2.9%-6.0%; P < .001), low hyperopia (82.8% vs 74.0% = 8.8%; 95% CI, 6.0%-11.8%; P < .001), premyopia (8.7% vs 21.6% = -12.9%; 95% CI, -15.4% to -10.4%; P < .001), and myopia (1.3% vs 1.8% = -0.5%; 95% CI, -1.3% to 0.4%; P = .30). Conclusions and Relevance: This study found that use of atropine for cycloplegia in preschool children was associated with less myopic refraction compared with cyclopentolate and may potentially avoid overestimation of premyopia prevalence; however, this investigation did not evaluate each cycloplegic agent in the same children.