September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Efficacy, predictability, and astigmatic correction error of Small Incision Lenticule Extraction for myopic astigmatism – a prospective 12-month study
Author Affiliations & Notes
  • Iben Bach Pedersen
    Department of Ophthalmology, Aarhus University Hospital, Aarhus , Denmark
  • Anders Ivarsen
    Department of Ophthalmology, Aarhus University Hospital, Aarhus , Denmark
  • Jesper Hjortdal
    Department of Ophthalmology, Aarhus University Hospital, Aarhus , Denmark
  • Footnotes
    Commercial Relationships   Iben Pedersen, None; Anders Ivarsen, None; Jesper Hjortdal, Carl Zeiss Meditec (R)
  • Footnotes
    Support  Carl Zeiss Meditec, Jena, Germany
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 4847. doi:
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      Iben Bach Pedersen, Anders Ivarsen, Jesper Hjortdal; Efficacy, predictability, and astigmatic correction error of Small Incision Lenticule Extraction for myopic astigmatism – a prospective 12-month study. Invest. Ophthalmol. Vis. Sci. 2016;57(12):4847.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : To evaluate refractive and visual outcome after Small Incision Lenticule Extraction (SMILE) for myopic astigmatism with 12 months follow up.

Methods : The prospective clinical trial comprised 101 myopic-astigmatic eyes (101 patients) treated with SMILE (cylinder from -4.00D to -0.75D). Preoperative, 1-week, and 1, 3, 6, 9, and 12 month examination included manifest refraction, uncorrected (UDVA), and corrected (CDVA) distance visual acuity. To assess the change in postoperative astigmatism, manifest refraction data were converted from spectacle to corneal plane in plus cylinders. Cylinder axis from included left eyes was flipped vertically to avoid the risk of orientation errors. By Alpins method, Target Induced Astigmatism Vector (TIA) and Surgically Induced Astigmatism Vector (SIA) were used to calculate Difference Vector (DV; postoperative astigmatism when target is emmetropia), Error of magnitude (EM; magnitude of DV), Error of angle (EA; axis of SIA subtracted axis of TIA), Correction Index (CI; magnitude ratio of SIA and TIA), and Index of success (IOS; magnitude ratio of DV and TIA). Kruskal-Wallis and Wilcoxon Rank test were used for comparison (non-Gaussian distribution).

Results : Preoperative refraction averaged -5.87D±2.13D in sphere and -1.82±1.00D in cylinder. After 12 months, 74% and 93% of eyes were within ±0.50D and ±1.00D of attempted refraction. LogMAR UDVA and logMAR CDVA averaged 0.03±0.16 and -0.08±0.09 after 12 months, respectively. UDVA remained stable in the postoperative period (p>0.19).
Mean DV was 0.47x91° at 12-month follow-up. No significant differences were seen in residual cylinder values during the postoperative period. Mean EM was 0.12±0.44D, while arithmetic EA was 0.28±15°, significantly different from zero (Table 1).
In predictability regression analysis of SIA and TIA, an under-correction of approx. 10% was observed at 12-month examination. CI was 0.94±0.38, while IOS was 0.40±0.41 at 12-month follow-up, with no significant changes during the postoperative period.

Conclusions : Treatment of astigmatism with SMILE seems to be predictable, effective, and compareble to what is seen after LASIK treatments. However, there seems to be an astigmatic under-correction of approx. 10%, with a very small counter clockwise position of the axis.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

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