Characterization of LASIK–modified Donor Corneas with a Distorted Grating–based Wavefront Sensor

Abstract

Abstract: : Purpose: To assess the effectiveness of a distorted grating–based wavefront analysis system in the characterization of donor corneas which have undergone LASIK prior to the donor’s death. We have previously demonstrated the potential of this technique as a screening tool for detecting corneas that have been modified through refractive procedures such as LASIK. The present study evaluates the wavefront analysis technique as a means of characterizing the specific refractive modifications made to the donor corneas. Methods: A phase diversity–based wavefront measurement system utilizing a distorted–grating was used to make wavefront measurements on 17 corneas. These corneas had undergone Excimer laser refractive surgery (LASIK or LASEK) prior to the donor’s death. Refractive treatment information was obtained for each of the corneas. The scientists making the wavefront measurements were masked from the donor history information. The resulting wavefront data was reduced to Zernike coefficients and these were correlated to the treatment sphere and cylinder values from the donor history. Results: A moderately–high degree of correlation was found between several of the Zernike coefficients and the treatment sphere and cylinder values. Measured trefoil and spherical aberrations had correlations in excess of 0.5 while astigmatism showed a correlation in excess of 0.8. Correlation increased with higher degrees of cylinder. Conclusions: This data suggests that a distorted grating–based wavefront sensor shows promise as a means for characterizing the magnitude of pre–mortem Excimer laser treatment performed on donor corneas. Acknowledgements: NEI Contract #EY013654, New Mexico Lion’s Eye Bank, Tissue Banks International, and corporate funding from Kestrel Corporation.

Keywords: imaging/image analysis: clinical • refractive surgery: LASIK • refractive surgery: corneal topography