Purpose: To explore short-term refractive and ocular parameter changes and their correlations after cycloplegia with tropicamide.
Methods: This study prospectively enrolled 114 right eyes of 114 participants (mean [±SD] age, 9.1 [±2.8] years). Spherical equivalent of refractive error (SER), axial length (AL), corneal curvature (CC), and anterior chamber depth (ACD) were measured before and after 30 minutes from instillation of 0.4% tropicamide. A partial optical coherence interferometry (Zeiss IOLMaster) was used for ocular parameter measurement. Refractive change and ocular parameter changes after cycloplegia and their correlations were evaluated.
Results: Spherical equivalent of refractive error, AL, and ACD all positively shifted significantly at 30 minutes after application of 0.4% tropicamide (p < 0.0001 for each parameter measured). After cycloplegia, 28 eyes (24.6%) had a hyperopic shift of more than 0.25 diopters (D), 3 eyes (2.6%) had a myopic shift of more than 0.25 D, and 83 eyes (72.8%) had their SER changes within -0.25 to 0.25 D. The mean, maximum, and minimum keratometric values all decreased (p = 0.005, 0.03, and 0.05, respectively), whereas corneal astigmatism did not change significantly. The changes in AL, ACD, or mean keratometric values contributed little to the refractive changes after cycloplegia by tropicamide (p > 0.05, pr ≤ 0.01 for all values).
Conclusions: Spherical equivalent of refractive error, AL, and ACD all positively shifted after cycloplegia with tropicamide. Corneal curvature became flattened after cycloplegia with tropicamide, but the corneal astigmatism did not change significantly. Refractive changes did not correlate with changes in AL, ACD, or CC after cycloplegia with tropicamide.