Predictability of different calculators to minimise postoperative astigmatism after the implantation of a toric intraocular lens

Session Details

Session Title: Toric IOL Calculations & Alignment

Session Date/Time: Sunday 23/09/2018 | 08:00-10:00

Paper Time: 08:18

Venue: Room A5

First Author: : F.Ribeiro PORTUGAL

Co Author(s): :    T. Ferreira   C. Relha   C. Esteves   S. Gaspar           

Abstract Details

Purpose:

To assess the efficacy of five different calculators for toric intraocular lens (IOL) power calculation by evaluating the mean absolute error (MAE) and the predicted residual astigmatism (PRA).

Setting:

Hospital da Luz, Lisbon, Portugal

Methods:

Retrospective comparative case series in cataract patients undergoing implantation of trifocal toric IOLs (PhysIOL FineVision POD FT). Inclusion criteria were age-related cataract and a corneal astigmatism between 0.90 and 4.50 D. Five different calculators were compared. Furthermore, two groups were differentiated according to the type of astigmatism: with the rule (27 eyes) and against the rule (16 eyes). The MAE and the centroid errors in the PRA from each calculator were evaluated.

Results:

Fifty-one eyes of 43 patients were included. For the standard toric calculator using anterior keratometry values only, the centroid prediction error was 0.39 D ±0.41@166º, which was reduced by the application of the PhysIOL toric calculator that includes the Abulafia-Koch formula and adjustment for the effective lens position (0.05 D ±0.34@167º) and also by the application of the Barrett toric calculator (0.07 D ±0.28@160º). Regarding the techniques that directly evaluate the posterior corneal surface, the using total corneal power provided by a color-LED topographer generated better results (0.10 D ±0.44@156º) than those using Scheimpflug camera data (0.23 D ±0.56@158º).

Conclusions:

The PhysIOL and the Barrett toric calculators taking into account the posterior corneal astigmatism by regression formulas, yielded lower astigmatic prediction errors compared to a standard toric calculator based on anterior keratometry data only. When total corneal power measurements were used, prediction errors were lower with color-LED than with Scheimpflug based topography.

Financial Disclosure:

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