Precision of refractive predictability of five intraocular lens power calculation formulas in short eyes

Session Details

Session Title: IOL Power Calculations, Post-LASIK & Extreme Eyes

Session Date/Time: Tuesday 25/09/2018 | 14:00-16:00

Paper Time: 15:40

Venue: Room A2

First Author: : A.Shrivastava INDIA

Co Author(s): :    P. Behera   S. Patel                 

Abstract Details

Purpose:

To analyse the accuracy of five intraocular lens (IOL) power calculation formulas in predicting refractive outcome in eyes with axial length (AL) less than 22 mm.

Setting:

Department of Ophthalmology, All India Institute of Medical Sciences, Raipur, India.

Methods:

Study protocol was approved by Institute ethics committee. Pre-operative, intra-operative, post-operative and refractive data was collected for all patients. Biometry was done using Partial coherence Interferometry. Five IOL power calculation formulas were included: SRK II, SRK/T, Hoffer -Q, Holladay 2 and Haigis. The mean numerical error (MNE) was defined as the difference between actual post–operative Spherical Equivalent (SE) at one month follow up and predicted postoperative SE. A negative predictive error indicated more myopic results i.e. tendency towards over correction and vice-versa. The mean absolute error (MAE) was calculated as the magnitude of prediction error, regardless of sign.

Results:

Fifty eyes of forty six patients were recruited for this study. Holladay 2 formula had the best MNE (-0.061) and MAE (0.686) when compared with other formulae. It also statistically proved to be better in predicting accuracy of IOL power calculation in eyes with AL less than 22 mm as compared to Haigis (P=0.0001), SRK/T (P=0.029), SRK II (P=0.020). However, one way ANOVA test showed no statistical significance when Holladay 2 was compared with Hoffer-Q (P=0.212). The proportion of eyes achieving absolute error within the dioptric range of ±0.5D, ±1.0D and ±2.0D of target for each formula was also calculated.

Conclusions:

Holladay 2 proved to be better than Haigis, SRK/T, SRK II, and at par with Hoffer-Q in predicting IOL power for eyes with axial length less than 22mm. But we recommend Holladay 2 over Hoffer-Q as the former uses seven variables in contrast to two in Hoffer-Q for IOL power estimation.

Financial Disclosure:

-