April 2014
Volume 55, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2014
Role of Percentage of Tissue Altered (PTA) as a risk factor in eyes with Normal preoperative topography that developed Ectasia after LASIK
Author Affiliations & Notes
  • Marcony Rodrigues Santhiago
    Ophthalmology, Federal University of Rio de Janeiro, Rio de janeiro, Brazil
    Refractive Surgery - Ophthalmology, University of Sao Paulo, Sao Paulo, Brazil
  • David Smadja
    University Hospital of Bordeaux, Bordeaux, France
  • Beatriz Gomes
    Ophthalmology, Federal University of Rio de Janeiro, Rio de janeiro, Brazil
  • Steven E Wilson
    Cleveland Clinic, Cleveland, OH
  • Glauco Mello
    Refractive Surgery - Ophthalmology, University of Sao Paulo, Sao Paulo, Brazil
  • Mario L R Monteiro
    Refractive Surgery - Ophthalmology, University of Sao Paulo, Sao Paulo, Brazil
  • James Bradley Randleman
    Emory Eye Center and Emory Vision, Atlanta, GA
  • Footnotes
    Commercial Relationships Marcony Santhiago, None; David Smadja, None; Beatriz Gomes, None; Steven Wilson, None; Glauco Mello, None; Mario Monteiro, None; James Randleman, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 1548. doi:
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      Marcony Rodrigues Santhiago, David Smadja, Beatriz Gomes, Steven E Wilson, Glauco Mello, Mario L R Monteiro, James Bradley Randleman; Role of Percentage of Tissue Altered (PTA) as a risk factor in eyes with Normal preoperative topography that developed Ectasia after LASIK. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1548.

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

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Abstract 
 
Purpose
 

The purpose of this study was to investigate in detail the theoretical role of the percentage of tissue altered (PTA) on ectasia after LASIK in eyes with normal preoperative topography compared to risk factors already know.

 
Methods
 

This retrospective comparative study included eyes that developed ectasia with normal preoperative topography. Consecutive LASIK cases with preoperative normal topography that have not developed ectasia served as control. Cases were identified after a detailed analyzes of cases that were referred to the authors’ institution. The PTA is calculated through the sum of flap thickness (FT) plus the ablation depth (AD) divided by the preoperative central corneal thickness (CCT). [PTA = (FT + AD)/CCT]. Patient age, spherical equivalent refraction, CCT, and topographic patterns; perioperative characteristics, including flap thickness, ablation depth, residual stromal bed and PTA were investigated.

 
Results
 

Thirty eyes met inclusion criteria for this study. PTA was significantly higher in patients with ectasia and normal topography compared to controls. Analyzes of the eyes that developed ectasia with normal topography revealed the PTA as the most prevalent risk factor (p < 0.0001) and the stepwise logistic regression revealed the PTA with the higher influence on ectasia and a higher odds ratio followed by RSB, Age and MRSE. CCT was the risk factor with less influence

 
Conclusions
 

The PTA seems to be a significant risk factor for ectasia in eyes with pre operative normal topography compared to controls. The PTA presented a higher influence on ectasia compared to other risk factors in eyes with normal preoperative topography.

 
Keywords: 680 refractive surgery: complications • 683 refractive surgery: LASIK  
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