Assessing standard astigmatism outcomes after refractive laser surgery

Session Details

Session Title: LASIK & PRK I

Session Date/Time: Sunday 15/09/2019 | 16:30-18:00

Paper Time: 16:42

Venue: Free Paper Forum: Podium 3

First Author: : N.Alpins AUSTRALIA

Co Author(s): :    G. Stamatelatos                             

Abstract Details

Purpose:

To identify the key parameters required in the analysis of astigmatism mega data after refractive laser surgery.

Setting:

NewVision Clinics, Melbourne, Australia

Methods:

Analysis of astigmatic outcomes for 9117 patients, 15612 cases, post LASIK and Photoastigmatic Refractive Keratectomy (PARK) with the ViSX STAR S4 excimer laser was performed using free web calculator software. The key vectorial parameters of the Target induced astigmatism vector (TIA), the Surgically induced astigmatism vector (SIA), the Difference vector (DV) and the Correction Index (CI) were analysed and displayed on a polar diagram with summated vector and geometric means. Secondary basic astigmatism analyses using double angle astigmatism diagrams were also performed displaying preoperative astigmatism compared with postoperative astigmatism using the centroid.

Results:

Using refractive parameters the mean arithmetic TIA and the summated vector mean (SVM) was 1.07+/-0.82D and 0.50D x 3 consecutively, SIA 1.03+/-0.87D and 0.30D x 6, DV 0.47+/-0.49D and 0.10D x 177 the CI 0.93. Analysis by corneal parameters the mean arithmetic SIA and the SVM was 1.27+/-1.75D and 0.70D x 5 consecutively, DV 1.03+/-1.71D and 0.10D x 93 and the CI 0.83.

Conclusions:

The standard astigmatic parameters of TIA, SIA, DV and CI use vectorial analysis to determine the amount of astigmatism treated, the amount od astigmatism corrected, the postoperative astigmatism remaining and whether the astigmatism was over or under corrected post refractive laser surgery. Double angle display of astigmatism pre and postoperatively is a comparison of magnitude analysis displayed at double the axis. An overall under correction in the mega data displayed that the correction of astigmatism requires a nomogram adjustment to future treatments may benefit from up to a 10% boost.

Financial Disclosure:

gains financially from competing product or procedure, gains financially from product or procedure presented