Comparison of the clinical effectiveness of correcting different types of astigmatism with small incision lenticule extraction (SMILE)

Session Details

Session Title: Small Lenticule Extraction

Session Date/Time: Tuesday 25/09/2018 | 08:00-10:30

Paper Time: 09:30

Venue: Room A3, Podium 3

First Author: : E.Igras POLAND

Co Author(s): :    B. Czarnota-Nowakowska   P. Krzywicki                 

Abstract Details

Purpose:

Few studies have reported outcomes in myopic astigmatism after Small Incision Lenticule Extraction (SMILE) or its differential effects on different types of astigmatism. The purpose of this study was to evaluate and compare the surgical effectiveness of SMILE for patients presenting for surgical correction of their visual acuity with three different types of astigmatism: with-the-rule (WTR), against-the-rule (ATR) and oblique astigmatism.

Setting:

Optegra Laser Refractive Clinics in Szczecin and Poznan, Poland

Methods:

We conducted a retrospective chart review of all patients who underwent correction of myopic astigmatism using the 500-kHz VisuMax femtosecond laser (Carl Zeiss Meditec) between January 2016 and December 2017. Consecutive patients aged ≥21 with stable refractive errors (-0.5 to -10.0 D) and astigmatism 0.75 to 5 D were included. Patients were divided into three groups according to the type of astigmatism determined by corneal evaluation: WTR, ATR and oblique astigmatism. The cylinder was converted to polar values for analysis. Where available data from preoperative, 1-week, and 2-, 8-, and 12-month examinations were included.

Results:

In total, 209 patients (355 eyes) were available, mean age 32 years; 58.4% were female. 247 had WTR, 62 oblique and 46 ATR astigmatism. The overall mean preoperative spherical equivalent (SE) was -5.6 ±2.16D and cylinder -1.7 ±1D. After 12 months, the mean SE for WTR reduced from -5.6 to -0.4D and the mean cylinder from -2.0 to -0.36D. Eyes with oblique astigmatism improved from a mean SE of -4.0 to -0.63D, cylinder from -1.35 to -0.1D. For ATR, the improvement in SE (-4.0 to -0.05D) and cylinder (-1.25 to 0.08D) were statistically greater than for WTR and oblique astigmatism.

Conclusions:

This study confirms data showing that SMILE in myopic astigmatism provides reliable correction of SE. It is to our knowledge, one of the first studies to show that irrespective of subtype of astigmatism, SMILE improves visual outcomes. As eyes with ATR had a statistically significantly better preoperative mean SE and cylinder, this explains in part their significantly better scores compared to the other types of astigmatism at follow-up examination. As the sample was undersized to investigate the effects of SMILE on low versus high astigmatism according to subtype, further study is now required.

Financial Disclosure:

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