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Multi-formula optimization of second eye refinement according to direction of the prediction error of the first eye

Poster Details

First Author: P.Gil PORTUGAL

Co Author(s):    R. Matos   J. Pires   M. Cardoso   E. Costa   M. Mariano        

Abstract Details


To determine if the refractive outcome of the second eye (SE) can be improved by adjusting the intra-ocular lens (IOL) power for the magnitude and direction of first eye prediction error in a multi-formula analysis.


Ophthalmology Department, Centro Hospitalar Baixo Vouga, Portugal


Retrospective database study. One hundred and fifty six patients who underwent bilateral consecutive cataract surgery were identified. Prediction errors for the first (PE1) and second eyes (PE2) were obtained for 4 formulae (HofferQ, SRK II, SRK/T and Holladay1). The optimal correction factor (OCF) for each formula was determined as the one resulting in the lowest SE mean absolute error (MAE). A similar analysis was performed in the negative and positive PE1 subgroups.


The OCFs were 50% in HofferQ and SRK/T, 70% in SRK II and 40% in Holladay1. In all cases the resulting MAE was statistically different (p<0.05) from the no adjustment and full adjustment groups (0.31 compared with 0.38 and 0.35 respectively for HofferQ; 0.35 compared with 0.39 and 0.45 for SRK II; 0.28 compared with 0.33 and 0.33 for SRK/T; 0.29 compared with 0.36 and 0.32 for Holladay1). The OCFs in the negative PE1 subgroup were 10%, 50%, 30% and 20% respectively for HofferQ, SRK II, SRK/T and Holladay1. In the positive PE1 subgroup, the OCFs were respectively 70%, 80%, 70% and 70%.


Second eye refinement is a valid strategy for improving SE refractive outcomes. The OCF is formula-dependent, with less accurate formulas requiring higher OCFs. Outcomes can be further optimized by accounting for direction of PE1, with lower and higher OCFs respectively in patients experiencing negative and positive PE1.

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