Optimal Dataset Sizes for Constant Optimization in Published Theoretical Optical Formulae.

Purpose: To determine the optimal number of data points required for optimization of formulae for classical lens power calculation.Methods: A large dataset of preoperative biometric values was used to assess the convergence of formula constants in a number of established intraocular lens power calculation formulae.Results: In formulae with a single constant, 80 to 100 clinical data points are sufficient to obtain convergence. The Haigis formula (3 constants), requires 200 to 300 data points although refractive error converges more rapidly.Conclusions: In all formulae 80 to 100 clinical data points are sufficient to achieve a stable mean refractive error.