Multizone model for postsurgical corneas: analysis of standard and custom LASIK outcomes

A multizone model for postsurgical corneal topography is presented and applied to a comparative analysis of the outcome of standard and customized myopic LASIK. The different zones are segmented automatically by a clustering algorithm. The algorithm uses a set of three local descriptors, which corre...

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Bibliographic Details
Published in:Journal of Biomedical Optics 2008-07, Vol.13 (4), p.044035-0440312
Main Authors: Gonza´lez, Luis, Herna´ndez-Matamoros, Jose´ L, Navarro, Rafael
Format: Article
Language:English
Subjects:
ablation profile
Algorithms
Cornea
Cornea - physiopathology
Cornea - surgery
corneal aberrations
corneal topography
Corneal Topography - methods
Curvature
custom LASIK surgery
Errors
Humans
Keratomileusis, Laser In Situ - methods
Mathematical models
multizone model
Multizone models
physiological optics
Prognosis
Refractive Errors - diagnosis
Refractive Errors - physiopathology
Surgery, Computer-Assisted - methods
Topography
Treatment Outcome
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Summary:A multizone model for postsurgical corneal topography is presented and applied to a comparative analysis of the outcome of standard and customized myopic LASIK. The different zones are segmented automatically by a clustering algorithm. The algorithm uses a set of three local descriptors, which correspond to normalized physical magnitudes computed for each point of the corneal topography map: Gauss curvature, root-mean-square (RMS) fit error to an ellipsoid surface model, and distance to the center of the topographic map. Both presurgical and post-LASIK corneal topographies of 31 eyes were analyzed using monozone and multizone models. The patients were classified into three groups according to the different LASIK treatments applied: Allegretto, Zyoptix, and PlanoScan. For post-LASIK corneas, the multizone model provided a lower fit error, an average of versus (monozone). The comparative analysis of the three different LASIK treatments showed no improvement of custom over standard treatments. The outcomes of Zyoptix and PlanoScan were basically equivalent and consistent with previous findings: The higher-order aberration (HOA) increased by a factor of two. The increase in HOA was higher, by a factor of three, after the Allegretto treatment. The mutizone model shows a higher-fidelity representation and permits a deeper understanding of the postsurgical cornea.
ISSN:1083-3668
1560-2281
DOI:10.1117/1.2960621