Abstract
Abstract: :
Purpose: To investigate the role of corneal first surface spherical aberration in achieving better than 20/30 vision at both distance and near post-LASIK in four presbyopic hyperopes. Methods: To be eligible for the study, patients had to be at least 49 years of age. After LASIK surgery for hyperopia, subject needed visual acuities of 20/30- or better at both near and distance and manifest refractions with less than 0.50 diopters of error. Controls met the same requirements but had a near vision of 20/70 or worse postoperatively. Pre- and post-operative corneal topographies were converted into corneal wavefront errors using CT View at 2, 3 and 4 mm pupil sizes. Results: Surgery significantly shifted the spherical aberration term in negative direction for both subjects and controls for all pupil sizes. However, there was no statistically significant difference in amount of negative spherical aberration induced (delta Zº4) by hyperopic LASIK between patients and controls for any pupil size. Conclusion: An increase in the negative spherical aberration structure of the eye after hyperopic LASIK does not appear to be the significant factor contributing to "pseudo-accommodation'. Other factors, such as pupil size, residual accommodative amplitude and a small amount of residual myopia are more likely to explain the phenomenon.
Keywords: 369 cornea: clinical science • 304 accommodation • 427 hyperopia