PURPOSE
Corneal topography data expressed as corneal aberrations are frequently used to report corneal laser surgery results. However, the optical image quality depends on all optical elements of the eye, including the human lens. We investigated correlations between corneal and total wavefront aberrations and the relevance of corneal aberrations for representing the optical quality of the total eye.
METHODS
Thirty-three eyes of 22 myopic patients were measured using a corneal topography system and a Tscherning-type wavefront analyzer. Pupils were dilated to at least 6 mm in diameter. All measurements were centered with respect to the line of sight. Corneal and total wavefront aberrations were calculated up to the 6th Zernike order in the same reference plane.
RESULTS
Statistically significant correlations (P<.05) between corneal and total wavefront aberrations were found for astigmatism (C3,C5) and all 3rd Zernike order coefficients such as coma (C7,C8). No statistically significant correlations were found for 4th, 5th, or 6th order Zernike coefficients. On average, all Zernike coefficients for corneal aberrations were larger than the Zernike coefficients for total wavefront aberrations.
CONCLUSIONS
Due to the lack of correlation between corneal and total wavefront aberrations in most of the higher order aberrations, measurement of corneal aberrations are of limited use for representation of the optical quality of the human eye, especially after corneal laser surgery. Corneal aberrations and optical elements within the eye are optically balanced. As a consequence, ideal customized ablations must take both corneal and total wavefront aberrations into consideration. [J Refract Surg 2003;19:104-112]
AUTHORS
From the University of Zurich, Dept. of Ophthalmology, Zurich, Switzerland (all authors), the Departamento de Oftalmologia, Santa Casa de Sao Paulo, Brazil (Jankov), and the Swiss Federal Institute of Technology, Institute of Biomedical Engineering, Zurich, Switzerland (Mrochen and Bueeler). Dr. Mrochen is a scientific consultant of WaveLight Laser Technology AG, Erlangen, Germany.
This work was supported in part by the Swiss National Science Foundation and by a research grant from the University of Zurich.
Correspondence: Michael Mrochen, PhD, University of Zurich, Dept. of Ophthalmology, Frauenklinik Str. 24, CH-8091 Zurich, Switzerland. Tel: 41.1.255 4993; Fax: 41.1.255 4472; E-mail: Michael.Mrochen@aug.usz.ch
Received: December 18, 2001
Accepted: September 20, 2002
