Posters

Can preoperative autorefraction reveal the risk of unintended postoperative astigmatism after small incision lenticule extraction for myopia?

Poster Details

First Author: A.Ivarsen DENMARK

Co Author(s):    A. Gyldenkerne   J. Hjortdal                 

Abstract Details

Purpose:

Correction of myopia with small incision lenticule extraction (SMILE) may cause induction of an unintended postoperative cylinder. We examined whether autorefraction or autokeratometry may be used to identify myopic patients at risk of developing postoperative subjective astigmatism.

Setting:

University eye clinic.

Methods:

One eye from 359 patients treated with SMILE for high myopia without astigmatism were evaluated with subjective refraction, autorefraction (AR) and auto-keratometry (AK) before and 3 months after surgery. Vector analysis of pre- and postoperative data was used to examine the risk of inducing a clinically significant subjective cylinder (defined as 0.75 D) or more. Statistical analyses included t-test, Chi2 and Hotelling’s T2 for vectorial comparisons.

Results:

Subjective astigmatism changed from zero preoperatively to 0.37D postoperatively (p<0.001). AR astigmatism increased from 0.30D to 0.57D (p<0.001) and AK astigmatism from 0.52D to 0.76D (p<0.001). Vector analysis showed significant difference between postoperative subjective astigmatism and preoperative AR or AK astigmatism (p<0.001). However, a preoperative AR cylinder of ³0.75D increased the risk of an induced subjective cylinder ³0.75D from 19 to 43% (RR=2.28), and the induced subjective cylinder magnitude correlated with preoperative AR astigmatism (r=0.26; p<0.001). Similar observations occurred in AK astigmatism.

Conclusions:

A high preoperative objective cylinder on keratometry or autorefraction significantly increases the risk of unwanted postoperative astigmatism after SMILE for myopia. During preoperative subjective refraction the investigator should be aware of objective cylinders.

Financial Disclosure:

... travel has been funded, fully or partially, by a company producing, developing or supplying the product or procedure presented