Bias correction in the intraocular lens power calculation beyond the effective lens position through the corneal fictitious index fitting with a thick lens paraxial formula

Session Details

Session Title: Posterior Capsule Opacification/IOL Power Calculations

Session Date/Time: Tuesday 17/09/2019 | 14:00-16:00

Paper Time: 15:40

Venue: Free Paper Forum: Podium 2

First Author: : J.Fernández SPAIN

Co Author(s): :    M. Rodriguez-Vallejo   J. Martínez   A. Tauste   D. Piñero                    

Abstract Details

Purpose:

To identify the sources of error in predictability beyond the Effective Lens Position and to develop two new thick lens equations.

Setting:

Qvision, Ophthalmology Department Vithas Virgen del Mar Hospital

Methods:

Retrospective observational case series with 43 eyes implanted with Liberty Trifocal (Medicontur). Information related to the actual lens position, corneal radii measured with specular reflection (IOL Master 500) and Scheimpflug-based (Pentacam HR) technologies and the characteristics of the implanted lenses (radii and thickness) were used for obtaining the fictitious indexes that better predicted the postoperative spherical equivalent (SE) when the real Effective Lens Position (ELP) was known. These fictitious indexes were used to develop two thick lens equations that were compared with the predictability of SRK/T and Barrett Universal II.

Results:

The SE relative to the intended target was correlated to the difference between real ELP and the value estimated by SRK/T (dELP) (r = -0.47, p=0.002), but this only predicted 22% of the variability in a linear regression model. The fictitious index for the specular reflection (nk) and Scheimpflug-based devices (nc) were significantly correlated with axial length. Including both indexes fitted to axial length in the prediction model with the dELP increased the r-square of the model up to 83% and 39%, respectively. Equations derived from these fictitious indexes reduced the mean SE in comparison to SRK/T and Barrett II

Conclusions:

The predictability with the trifocal IOL evaluated was not completely explained by an error in the ELP prediction. An adjustment fitting the fictitious index with the axial length improved the predictability without false estimations of the ELP.

Financial Disclosure:

receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented, travel has been funded, fully or partially, by a company producing, developing or supplying the product or procedure presented, research is funded, fully or partially, by a company producing, developing or supplying the product or procedure presented