Posters

Predictibility of intraocular lens power calculation after refractive surgery

Poster Details

First Author: N.Masurel FRANCE

Co Author(s):    B. Cochener-Lamard                    

Abstract Details

Purpose:

As refractive surgery becomes more and more common, the senario of lens power calculation after retractive surgery will become frequent in the coming decades. These patients, often demanding and sometimes allergic to spectacles, will expect the best refractive result after cataract surgery especially if they ask for a diffractive multifocal lens. That is the reason why sharp predictibility of the pseudophakic lens power is of the essence. This survey aims at evaluating the accuracy of the current lens power calculation to approach emmetropia after refractive surgery.

Setting:

This monocentric retrospective study from consecutive case series between january 2012 and december 2016 has included 82 eyes of 48 patient that have received the bifocal diffractve lens AT Lisa after having experienced a refractive surgery.

Methods:

3 groups have been formed depending on the kind of refractive surgery the eye has received : radial keratotomy (RK), PRK/LASIK or phakic IOL. The predictibility of the different calculus strategies after refractive surgery (including ASCRS website) were computed and compared to the clinical 1 month result. The judgement criteria were the mean absolute error (MAE) and the percentage of eye below 0,5D error. A statistacal analysis for multiple comparisons and post hoc test was conducted with the Bonferroni correction.

Results:

In the RK group, Average ASCRS, Holladay 1 with double K method (DK) and the Barrett true K are the best formula in terms of MAE. The K-1 methods are less effective. In the phakic IOL group, 4th and 5th genaration formula show better results than the 3rd generation formula, in particular the Hill-RBF formula. In the PRK/LASIK group, without refractive history, the Masket and the Barrett true K are leading in terms of MAE whereas the Kiol (Holladay1) DK, Average ASCRS and Haigis L are on the podium taking accout of the refractive history. The medical history method proves to be underperforming.

Conclusions:

Even though this study failed to reach statistical signifiance, it shows the weakness of the medical history method and the K-1 method. Furthermore, results argue for better refractive predictibility with specific formulas such as the Barret True K, the Masket or the Hill-RBF formula depending on the refractive surgery that has been performed. This study highlights the relevance of the Barrett true K formula witch has been acknowledged by other studies.

Financial Disclosure:

None