Abstract
Abstract: :
Purpose: The introduction of custom ablation as a refinement of laser refractive surgery, and the use of this technique to try to create aberration-free eyes, has underscored the need to investigate the aberration profile of a normal population. Methods: 1000 normal eyes (spherical equivalent +2.00D to -3.00D, Sim-K up to 2.50D, BSCVA >=20/20) were selected from over 5000 topography maps. Topography data was converted to Zernike terms. Results: Astigmatism was the single most important aberration in these normal eyes, increasing substantially as the pupil diameter increased from 3.0 mm to 7.0 mm. Even at a pupil diameter of 7.0 mm, spherical aberration was a less prominent factor than astigmatism. There was a very wide spread of higher order aberrations even at a 3.0-mm pupillary diameter. Conclusions: This first large-scale documentation of the distribution of corneal aberrations in normal eyes indicates that astigmatism is the predominant optical aberration. It also shows a very wide range of values, suggesting that an aberration-free eye may be too simplistic a goal in refractive surgery. Although not providing a measure for the entire eye, these data appear relevant to the evolution of custom ablation because corneal aberrations are considered to account for at least 80% of the eye's total optical aberrations.
Keywords: refractive surgery • refractive surgery: comparative studies • refractive error development