April 2010
Volume 51, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2010
Correction of Myopia With Thermal Treatment of Anterior Cornea: Results With ex vivo Porcine Model
Author Affiliations & Notes
  • D. Borja
    Avedro Inc., Waltham, Massachusetts
  • R. Pertaub
    Avedro Inc., Waltham, Massachusetts
  • H. Loree
    Avedro Inc., Waltham, Massachusetts
  • D. Muller
    Avedro Inc., Waltham, Massachusetts
  • Footnotes
    Commercial Relationships  D. Borja, Avedro Inc., E; R. Pertaub, Avedro Inc., E; H. Loree, Avedri Inc., E; D. Muller, Avedro Inc., E.
  • Footnotes
    Support  None.
Investigative Ophthalmology & Visual Science April 2010, Vol.51, 4216. doi:
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      D. Borja, R. Pertaub, H. Loree, D. Muller; Correction of Myopia With Thermal Treatment of Anterior Cornea: Results With ex vivo Porcine Model. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4216.

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

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Abstract
 
Purpose:
 

To characterize the change in shape and refractive power of ex vivo porcine corneas after Keraflex (KFX), a microwave-based approach to thermal keratoplasty for myopic correction.

 
Methods:
 

Annular thermal lesions were induced on the anterior corneas of 27 fresh ex vivo porcine globes (post mortem time < 1day). KFX was performed with a 4.5 mm inner dia. x 200 µm thick inner diameter electrode and a 6.5 mm outer dia. coaxial ground electrode with microwave frequency of 915MHz and energies of 1-8J. The geometry of the thermal lesion and the refractive power change due to anterior cornea shape change were assessed from pre- and post-KFX cross sectional Scheimpflug slit-lamp images acquired along 32 meridians. The anterior corneal surface profiles were obtained from each image and fit with a conic section function to determine radii of curvature and asphericity. The SimK refractive power of the anterior cornea pre- and post-KFX was calculated using the instantaneous radius of curvature over an 8mm pupil diameter.

 
Results:
 

Stromal shrinkage occurred below the inner electrode. Approximate lesion depth (LD) increased linearly with energy (LD [µm] = 19.6+23.4 [µm/J] * Energy [J], r=0.72 and p<0.0001) as did the change in anterior corneal surface refractive power (ΔPower [D] = -0.75 + 1.01 [D/J]* Energy [J], r=0.85 and p<0.0001).

 
Conclusions:
 

In an ex vivo porcine cornea model, KFX flattens the shape of the anterior cornea, which reduces its refractive power and can correct for myopia. The extent of corneal flattening is a linear function of applied energy. These results are qualitatively similar to those of previous human studies of KFX (unpublished), suggesting that this ex vivo model is a useful tool for optimization of the clinical KFX treatment.  

 
Keywords: refractive surgery: other technologies • myopia • refractive surgery: corneal topography 
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