Phacoemulsification, capsulorhexis, and intraocular lens power prediction accuracy

Phacoemulsification with capsulorhexis reduces the surgical variability and may result in a more predictable refractive outcome. To evaluate the prediction accuracy with current IOL power prediction formulas, we reviewed a retrospective series of 628 phacoemulsification cases, including 148 short (< 22 mm) and 80 long (> 25 mm) eyes. Using the Binkhorst II formula and the manufacturer's recommended anterior chamber depth (ACD) values, the mean absolute refractive prediction error was 0.56 diopters (D). This error could be reduced to 0.51 D by retrospectively optimizing the ACD values for each lens type. Under similar least error conditions, the mean error was 0.51 D with the SRK/T formula and 0.47 D with the Olsen formula (P < .01). The Binkhorst formula overestimated the refraction in short eyes and underestimated the refraction in long eyes. The SRK/T and the Olsen formula were unbiased with the axial length. We hypothesize that the high prediction accuracy may be partially explained by a more predictable pseudophakic ACD with the current surgical technique.