Premium
Analysis of optimized profiles for ‘aberration‐free’ refractive surgery
Author(s) -
ArbaMosquera Samuel,
De Ortueta Diego
Publication year - 2009
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1111/j.1475-1313.2009.00670.x
Subject(s) - coma (optics) , emmetropia , cornea , spherical aberration , zernike polynomials , aberrations of the eye , ophthalmology , corneal topography , wavefront , optics , refractive surgery , astigmatism , visual acuity , optical aberration , ray tracing (physics) , lens (geology) , medicine , refractive error , physics
Purpose: To provide a model of an aberration‐free profile and to clinically evaluate the impact of treatments based upon these theoretical profiles in the post‐operative cornea. Methods: Aberration‐free profiles were deduced from the Zernike expansion of the difference between two corneal cartesian‐ovals. Compensation for the focus‐shift effects of removing corneal tissue were incorporated by preserving the location of the optical focus of the anterior corneal surface. Simulation of the surgical performance of the profile was performed by means of simulated ray‐tracing through a cornea described by its anterior surface and pachymetry. Clinical evaluation was retrospectively analysed in terms of visual outcomes, corneal wavefront aberration and asphericity changes at 3‐month follow‐up compared to the baseline on 100 eyes treated for compound myopic astigmatism. Results: The proposed ‘aberration‐free’ profiles theoretically preserve aberrations, becoming more oblate asphericity after myopic treatments, and more prolate after hyperopic ones. In the clinical evaluation, 94% of eyes were within ±0.50 D of emmetropia. BSCVA improved significantly ( p < 0.001). Induced corneal aberrations at 6‐mm were below clinically relevant levels: 0.123 ± 0.129 μm for HO‐RMS ( p < 0.001), 0.065 ± 0.128 μm for spherical aberration ( p < 0.001) and 0.058 ± 0.128 μm for coma ( p < 0.01), whereas the rate of induced aberrations per achieved D of correction were −0.042, −0.031, and −0.030 μm D −1 for HO‐RMS, SphAb, and coma (all p < 0.001). Induction of positive asphericity correlated to achieved correction ( p < 0.001) at a rate 3× theoretical prediction. Conclusions: ‘Aberration‐free’ patterns for refractive surgery as defined here together with consideration of other sources of aberrations such as blending zones, eye‐tracking, and corneal biomechanics yielded results comparable to those of customisation approaches. Having close‐to‐ideal profiles should improve clinical outcomes decreasing the need for nomograms, and diminishing induced aberrations after surgery.