Comparisons of Using Cycloplegic Biometry Versus Non-cycloplegic Biometry in the Calculation of the Cycloplegic Refractive Lens Powers

IntroductionThis study investigated the difference between the calculation of cycloplegic crystalline lens power (LP) using non-cycloplegic and cycloplegic biometry data in children, and associated factors were explored.MethodsA total of 821 children were enrolled and only right eye was analyzed. The corneal radii (CR), corneal power (CP), anterior chamber depth (ACD), lens thickness (LT), and axial length (AL) before and after cycloplegia were obtained using IOLMaster 700. Anterior segment length (ASL) was defined as ACD plus LT. The cycloplegic LP was calculated with Bennett’s formula. In addition, LP calculated with cycloplegic data was defined as cLP, otherwise it was defined as nLP. The ΔLP (defined as the value as cLP minus nLP) was compared among age, gender, and refractive states groups. Associated factors of ΔLP and |ΔLP| were explored by Pearson’s correlation and multivariate linear regression.ResultsThe mean age of the 821 subjects was 9.83 ± 2.97 years with a mean spherical equivalent refraction (SER) of − 1.06 ± 2.12 D. Overall, the ACD, LT, and ASL were significantly affected by cycloplegia agent (all p < 0.001; paired t test). Conversely, no statistically significant differences were documented in AL, CP, or AL/CR ratio before and after inducing cycloplegia (p = 0.917, p = 0.515, and p = 0.549, respectively). Significant difference was found between nLP and cLP (21.24 ± 1.58 D vs 21.43 ± 1.92 D, p = 0.001). The mean ΔLP was 0.11 ± 0.87 D (range from − 7.01 D to 7.08 D). Significant change in LP was found in low and medium groups, respectively (0.13 ± 0.81 D, p = 0.001; 0.11 ± 0.48 D, p = 0.043). In the multiple regression analysis, |ΔLP| was exclusively associated with ΔASL (β = 0.172, [95% CI 0.112–0.300], p < 0.001).ConclusionOur results indicated that using cycloplegic biometry could lead to an overestimation in LP for low and moderate myopia eyes. This finding is likely to facilitate the refractive development research in children.Trial RegistrationClinicalTrials.gov identifier, NCT05247099.