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Comparative study of 9 different formulae for intraocular lens power calculation

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Session Details

Session Title: Cataract Surgery Outcomes: IOL Power Calculations

Session Date/Time: Sunday 08/10/2017 | 14:30-16:00

Paper Time: 15:00

Venue: Meeting Center Room I

First Author: : M.Lee MALAYSIA

Co Author(s): :    Y. Lee                    

Abstract Details

Purpose:

To compare the ease of use and the accuracy of the pre-installed intraocular lens(IOL) power calculation formulae of the Lenstar Optical Biometer (SRK-T, Hoffer-Q, Holladay-I, Haigis, Olsen and Barrett Universal II) and the Holladay-II, Radial Basis Function (RBF) and Ladas Super Surface formulae.

Setting:

Lee Eye Centre, Ipoh, Malaysia

Methods:

200 eyes which underwent cataract surgery with a single IOL platform by a single surgeon, had IOL power calculation performed using the pre-installed formulae from the Lenstar, the Holladay IOL Consultant(Holladay-II) and the respective online calculators for RBF and Ladas formulae. No IOL constant optimisation was done as the intention was to evaluate the accuracy of all the formulae “as it is”. Manifest refraction was carried out at 1 month postoperatively and the Prediction Error(PE) and Mean Absolute Error(MAE) for each formula was calculated. Statistical analysis was done using Barrett as the standard for comparison.

Results:

The MAE was 0.35D(SRK-T), 0.39D(Hoffer-Q), 0.37D(Holladay-I), 0.38D(Haigis), 0.48D(Holladay-II), 0.43D(Olsen), 0.32D(Barrett), 0.39D(RBF) and 0.33(Ladas). The PE within 0.5D of target was 74.5%(SRK-T), 71%(Hoffer-Q), 72.5%(Holladay-I), 69.5%(Haigis), 54%(Holladay-II), 66.5%(Olsen), 76.5%(Barrett), 69.5%(RBF) and 77.5%(Ladas). The Holladay-II and Olsen were statistically significantly different.

Conclusions:

The Barrett and Ladas formulae were the most accurate (with the lowest MAE) and highest proportion of eyes within 0.5D of target. All the formulae were comparable except for the Holladay-II and Olsen. Improved accuracy would be expected with optimisation and this would be more important for the complex formulae which require more parameters for calculation.

Financial Disclosure:

NONE

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