Accuracy of total corneal astigmatism measurement with a novel specular reflection technique

Session Details

Session Title: Corneal Astigmatism Assessment. Surgery Equipment

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

Paper Time: 12:40

Venue: Main Auditorium

First Author: : V.Sicam THE NETHERLANDS

Co Author(s): :    S. Klijn   C. van der Sommen   N. Reus              

Abstract Details

Purpose:

To evaluate the accuracy of total corneal astigmatism measurement with a novel specular reflection technique (Cassini, i-Optics).

Setting:

Rotterdam Ophthalmic Institute, Rotterdam, The Netherlands.

Methods:

Twenty-four eyes of 24 patients who underwent routine cataract surgery with implantation of a monofocal nontoric intraocular lens (Acrysof SA60AT, Alcon) were enrolled. Tilt and decentration were assumed to be negligible; thus, total corneal astigmatism was assumed equal to refractive astigmatism. Refractive astigmatism was measured with autorefraction (ARK-530A, Nidek). A specular reflection technique (Cassini, i-Optics) was used to perform keratometry of the anterior and posterior corneal surfaces. Subsequently, total corneal astigmatism was calculated using only anterior keratometry as well as using keratometry of both corneal surfaces. The error of either approach was defined as the absolute difference with refractive astigmatism.

Results:

Mean astigmatic magnitude was 0.92 ± 0.44 D. Mean cylinder magnitude measurement error was 0.29 ± 0.21 D using only anterior keratometry, and 0.27 ± 0.20 D using keratometry of both corneal surfaces. The error decrease in cylinder magnitude measurement was not statistically significant (P=0.60). Mean cylinder axis measurement error was 26.6 ± 38.7 degrees using only anterior keratometry, and 22.3 ± 38.5 degrees using keratometry of both corneal surfaces. The error decrease in cylinder axis measurement was statistically significant (P<0.01).

Conclusions:

In the calculation of corneal astigmatism, the accuracy of cylinder axis measurements with a novel specular reflection technique (Cassini, i-Optics) statistically significantly increases if keratometry of both corneal surfaces rather than only the anterior surface is used.

Financial Interest:

One of the authors is employed by a for-profit company with an interest in the subject of the presentation, One of the authors research is funded, fully or partially, by a company producing, developing or supplying the product or procedure presented, One of the authors receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented