Accuracy of Intraocular Lens Power Calculation Based on Distance from Haptic to Principal Object Plane

Purpose: To investigate the impact of the distance from the most-anterior surface of the optic to the principal object plane (POP) and from the foremost haptic to the principal object plane (H-POP) on the intraocular lens (IOL) power calculation.

Setting: A tertiary hospital.

Design: Optical simulation and retrospective cross-sectional study.

Methods: The optical simulation study plotted changes in the POP and H-POP as a function of IOL power using ICB00 IOL configuration data. The clinical study included 102 eyes of 102 patients implanted with ICB00 IOL to examine the correlation between changes in both the POP and the H-POP, and the prediction error calculated using the Barrett Universal II formula with varying IOL power.

Results: The ICB00 IOL showed minor fluctuations in the POP (0.21 mm to 0.30 mm) with changing IOL power. The H-POP increased stepwise from 5.0 D, peaking at 0.60 mm at 16.0 D, then decreased to a minimum of 0.14 mm at 34.0 D. The prediction error graph primarily mirrored the pattern of changes in the H-POP rather than the POP with varying IOL power. Linear regression showed a significant myopic shift in prediction error as IOL power increased beyond 16.0 D (Y = -0.069X+1.420, R2=0.178, p<0.001).

Conclusion: For the ICB00 IOL, the H-POP has more impact on IOL power calculation than the POP itself. For more accurate IOL power calculations, it is essential for all IOL manufacturers to provide comprehensive information on both optic and haptic geometries, which will enable the precise calculation of H-POP.