Ratio of Axial Length to Corneal Radius in Japanese Patients and Accuracy of Intraocular Lens Power Calculation Based on Biometric Data

PURPOSE: To evaluate the features of the axial length to corneal radius ratio (AL/CR) in Japanese patients with cataracts and determine the accuracy of intraocular lens (IOL) power calculation formulas according to the AL/CR features and the AL. DESIGN: Retrospective observational case series. METHODS: Setting: Clinical practice. PATIENT POPULATION: A total of 1,135 eyes (1,135 patients) with cataracts. OBSERVATION PROCEDURES: Measurement of the AL and CR by optical biometry and evaluation of the refractive outcomes using the SRK/T, Holladay 1, Hoffer Q, Haigis, and Barrett Universal II formulas. MAIN OUTCOME MEASURES: The features of the AL/CR ratio and the accuracy of IOL power calculations based on the AL/CR and the AL. RESULTS: The mean AL/CR was 3.15 +/- 0.19. Significant weak negative correlations were observed between the spherical equivalent (SE) and AL (r = -0.7489, P<0.001) and the SE and AL/CR (r = -0.8069, P<0.001); no correlation was found between the SE and CR (r = 0.0208, P = 0.483). For medium ALs and high AL/CRs, the SRK/T formula performed less accurately. For long ALs and high AL/CRs, the Holladay 1 and Hoffer Q formulas performed less accurately. The Barrett Universal II formulas performed well across a range of ALs and AL/CRs. CONCLUSIONS: The AL/CR explained the total variation in the SE better than the AL alone. Surgeons should pay attention to the selection of IOL power calculation formulas in eyes with high AL/CRs.