Abstract
Abstract: :
Purpose:We compare the high order ocular and corneal aberrations in a group of normal eyes to investigate the relationship between ocular and corneal optical quality. Methods:Corneal topography (Zeiss-Humphrey) and ocular aberrations maps (Wavescan, VISX) were obtained for 31 consecutive candidates for refractive surgery found to have normal ocular exams. Custom software was used to calculate corneal wavefront error maps (raytracing) that were fitted with a sixth order zernike polynomial expansion. Ocular wavefronts maps were obtained directly from the device as sixth order zernike expansions. The relationship between ocular and corneal aberrations (spherical aberration (SA), RMS coma (RMSc), RMS high order (RMSh) as well as RMS 3rd, 4th, 5th and 6th order) was investigated using linear regressions. Results:In most cases (25/31) corneal SA is greater than ocular SA with only 2 eyes having negative ocular SA and with a third eye having negative corneal SA. Regression results are presented using the form, aberration [slope, offset, r] in micrometers: RMSc [0.457, 0.136, 0.554]; RMS3 [0.523, 0.086, 0.50]; RMS 4 [0.542, 0.164, 0.39]; RMS 5 [0.813, 0.011, 0.68]; RMS 6 [0.283, 0.146, 0.01]; and RMSh [0.636, 0.193, 0.54]. Conclusion:On average the corneal aberrations of normal eyes show significant correlation with the equivalent ocular aberrations. Individual eyes can have large differences between ocular and corneal aberrations. It is essential to examine both ocular and corneal aberrations to understand vision in normal eyes.
Keywords: 500 optical properties • 599 topography • 519 physiological optics