May 2004
Volume 45, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2004
Higher–Order Aberration Changes After Corneal Refractive Therapy (CRT)
Author Affiliations & Notes
  • D.A. Berntsen
    College of Optometry, The Ohio State University, Columbus, OH
  • J.T. Barr
    College of Optometry, The Ohio State University, Columbus, OH
  • G.L. Mitchell
    College of Optometry, The Ohio State University, Columbus, OH
  • Footnotes
    Commercial Relationships  D.A. Berntsen, Paragon Vision Sciences (Mesa, AZ) F; J.T. Barr, Paragon Vision Sciences (Mesa, AZ) F; G.L. Mitchell, None.
  • Footnotes
    Support  none
Investigative Ophthalmology & Visual Science May 2004, Vol.45, 1543. doi:
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      D.A. Berntsen, J.T. Barr, G.L. Mitchell; Higher–Order Aberration Changes After Corneal Refractive Therapy (CRT) . Invest. Ophthalmol. Vis. Sci. 2004;45(13):1543.

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

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Abstract

Abstract: : Purpose: Corneal Refractive Therapy (CRT, Paragon Vision Sciences) utilizes gas permeable reverse return zone design contact lenses to reshape the cornea to achieve a reduction in myopia. The Complete Ophthalmic Analysis System (COAS, WaveFront Sciences), a Hartmann–Shack wavefront sensor, is used to measure the effects of corneal reshaping with CRT on higher–order aberrations of normal human eyes. Methods: The aberration profiles of sixteen myopic subjects (–1.25 D to –5.00 D, mean –2.72 D ± 0.96 D) between the ages of 21 and 37 were measured in the morning using the COAS. Subjects were correctable to 20/20 and free of ocular disease. Patients were then fit with CRT lenses in each eye. One month after the CRT lens fit was finalized, the patient’s aberration profile was again measured in the morning. The COAS was used to measure each dilated eye 8 times at both the baseline and one month visit. The right eye of each subject was selected and the average higher–order RMS wavefront error (3rd to 6th order) at each visit was calculated for a 5 mm pupil diameter and included in the analysis. A Wilcoxon Sign Rank Test was used to determine if the difference between the baseline and one month measurements was significantly different from zero (i.e. whether CRT resulted in a significant change in higher–order aberrations). An analysis of higher–order aberration change was repeated including only even order Zernike coefficients in the RMS error calculation (spherical–like aberrations) and again using only odd order Zernike coefficients in the RMS error calculation (coma–like aberrations). Results: The mean sphere component of the refractive error changed from –2.72 D ± 0.96 D to +0.55 D ± 0.39 D with an average change of +3.27 D ± 0.88 D. Total higher–order RMS error (in microns) increased from 0.1484 ± 0.0387 (mean ± SD) to 0.3173 ± 0.1066 with an average increase of 0.1689 ± 0.1196 (p=0.001, Wilcoxon Sign Rank Test). Even order RMS error (spherical–like aberrations) increased from 0.0768 ± 0.0249 to 0.2277 ± 0.0975 with an average increase of 0.1508 ± 0.1114 (p=0.001, Wilcoxon Sign Rank Test). Odd order RMS error (coma–like aberrations) increased from 0.1252 ± 0.0368 to 0.2110 ± 0.0807 with an average increase of 0.0857 ± 0.0824 (p=0.003, Wilcoxon Sign Rank Test). Conclusions: CRT results in an overall increase in the higher–order aberrations of the eye. While significant increases in both spherical–like and coma–like aberrations were measured, spherical–like aberrations appear to contribute more to the increase in higher–order aberrations than do coma–like aberrations.

Keywords: contact lens 
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