The effect of high posterior corneal astigmatism on toric IOL power calculation

Session Details

Session Title: Corneal Astigmatism Assessment. Surgery Equipment

Session Date/Time: Saturday 05/09/2015 | 11:00-13:00

Paper Time: 11:44

Venue: Main Auditorium

First Author: : G.Kleinmann ISRAEL

Co Author(s): :    O. Reitblat   A. Levi   A. Abulafia              

Abstract Details

Purpose:

To describe the effect of high posterior corneal astigmatism (PCA) on toric intraocular lens (IOL) power calculation.

Setting:

Ein-Tal Eye Center, Tel Aviv, Israel

Methods:

Consecutive cases of patients, who underwent cataract extraction with implantation of a toric IOL (Acrysof Alcon), were reviewed. Eyes with PCA equal or higher than 0.8 diopters (D), measured by the Pentacam, were included. The toric IOL power and axis calculated with vector analysis. The errors in the predicted residual astigmatism were calculated based on the manifest refraction 1 month postoperatively. The results were compared with the recommendation of the Holladay 2 Consultant Program, with and without adjustment of the Baylor toric IOL nomogram, and the Barrett toric calculator.

Results:

During the 2.5 years of the study period, 73 toric IOLs were implanted. 9 eyes (12%) of 8 patients, had PCA of 0.8D or higher, and were enrolled in the study. The anterior corneal astigmatism was with the rule astigmatism in all cases, range between 2.07D to 5.77D (mean±SD=3.62D±1.17). The mean PCA was 0.92D±0.11, range between 0.80D to 1.10D. The mean absolute and vector/centroid prediction errors were the lower using the vector analysis (0.59±0.35D, 0.21D@91.28, respectively) compared with the Holladay program (0.99±0.42D, 0.59D@175.10, respectively), the Baylor toric IOL nomogram (0.72±0.43D, 0.31D@94.29, respectively), and the Barrett's toric calculator (0.80±0.48D, 0.22D@107.83, respectively).

Conclusions:

Our study suggests that toric IOL power calculators and adjustment nomograms cannot compensate completely for high PCA. We suggest directly measuring the PCA and in cases of extreme high PCA to use vector analysis.

Financial Interest:

NONE