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D. T. Austin, S. Rae, A. Holland, S. Pardhan; Can Wavefront Aberrations of a Contact Lens on Eye Be Predicted From Combining Individual Wavefront Measurements of the Eye and Contact Lens?. Invest. Ophthalmol. Vis. Sci. 2009;50(13):6346.
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© ARVO (1962-2015); The Authors (2016-present)
Contact lenses to correct the eyes aberrations, primarily spherical aberration, may not perform as predicted due to tear film changes, lens flexure, lens rotation and translation1,2. This study compares the measured aberrations of the contact lens on eye to the combination of the eye alone and contact lens in vitro.
Three contact lens types of different optical designs and material characteristics were investigated (DefinativeTM, balafilcon A and nelfilcon A. Aberrations of the eye alone and the eye plus contact lens were measured with the COAS-HD aberrometer (Wavefront Sciences, USA) for 10 subjects and analysed for a 5mm aperture. In vitro measurements of contact lenses alone were obtained with the Clearwave aberrometer. Aberrations of contact lens on eye were compared to those of the eye alone plus contact lens in vitro. This study looked at how closely the expected performance and the actual performance matched. Data for the eye alone was subtracted from the eye plus contact lens (lens effect on eye) and compared to in vitro measurements of each contact lens for spherical aberration (Z4,0) and RMS coma, 3rd and 4th order and total RMS aberrations.
There was no significant difference in spherical aberration between the lens effect on eye and actual lens off eye, for any lens type (p>0.05). However, 3rd order RMS aberrations differed significantly on comparing the lens aberrations on eye to lens in vitro for the DefinativeTM lens (p=0.004). For nelfilcon A, the 3rd order (p=0.031) and total RMS (p=0.025) aberrations differed significantly.
Spherical aberration on eye was closest to expected values from in vitro measurements for all three lens types, showing that intended spherical aberration inherent in the lens design will have the expected effect on eye. Other aberration terms (RMS coma, 3rd, 4th order and total RMS) showed differences in the effect on eye from in vitro measurements, which could result from lens decentration, drape and changes in tear film properties when the lens was worn.1 Thibos, LN, Cheng, X, Bradley, A (2003). Eye and Contact Lens. 29: S167-170.2 Guirao, A, Williams, DR Cox, IG (2001). J. Opt. Soc. Am.Acad. 18: 1003-1015.
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