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Comparison of with-the-rule and against-the-rule astigmatism correction with SMILE

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Session Details

Session Title: Femtosecond Small Lenticule Extraction II

Session Date/Time: Tuesday 08/09/2015 | 16:30-18:30

Paper Time: 17:40

Venue: Room 17

First Author: : T.Archer UK

Co Author(s): :    D. Reinstein   G. Carp   M. Gobbe              

Abstract Details


To report the accuracy of refractive astigmatism correction using small incision lenticule extraction (SMILE).


London Vision Clinic, London, UK.


This was a retrospective analysis of 313 consecutive eyes with myopic astigmatism treated by SMILE. Inclusion criteria were spherical equivalent (SEQ) treated up to -10.00 D, refractive astigmatism treated of ≥0.75 D, and 3 month follow-up data available. A personalized nomogram was used for all treatments. Vector analysis was performed to evaluate the accuracy of refractive astigmatism correction using the Alpins method. The analysis was then repeated for groups according to the axis of astigmatism (positive cylinder notation): with-the-rule (WTR; 60˚-120˚), oblique (30˚-60˚ and 120˚-150˚), and against-the-rule (ATR; 0˚-30˚ and 150˚-180˚).


Mean SEQ was -4.84±2.01 D. Mean refractive astigmatism was 1.29±0.62 D (range: 0.75 to 4.25 D). Mean difference vector magnitude was 0.37 D. Geometric mean of the Correction Index (CI) was 1.08, but CI was >1 for the majority of eyes with ATR astigmatism. Mean Angle of Error was 0.28±8.19˚ with > 15˚ in 6%. Target Induced Astigmatism (TIA) vs Surgically Induced Astigmatism (SIA) slope was 1.09, compared to 0.86 using laser data entry. TIA vs SIA slope was 1.07 for the WTR group, 1.15 for the oblique group, and 1.32 for the ATR group.


Use of a personalized nomogram improved the accuracy of SMILE astigmatism correction. This may be further improved by using a continuous function according to the axis of the astigmatism.

Financial Interest:

One of the authors receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented

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