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Journal of Biomedical Optics

Numerical nonwavefront-guided algorithm for expansion or recentration of the optical zone
Author(s): Samuel Arba Mosquera; Shwetabh Verma
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Paper Abstract

Complications may arise due to the decentered ablations during refractive surgery, resulting from human or mechanical errors. Decentration may cause over-/under-corrections, with patients complaining about seeing glares and halos after the procedure. Customized wavefront-guided treatments are often used to design retreatment procedures. However, due to the limitations of wavefront sensors in precisely measuring very large aberrations, some extreme cases may suffer when retreated with wavefront-guided treatments. We propose a simple and inexpensive numerical (nonwavefront-guided) algorithm to recenter the optical zone (OZ) and to correct the refractive error with minimal tissue removal. Due to its tissue-saving capabilities, this method can benefit patients with critical residual corneal thickness. Based on the reconstruction of ablation achieved in the first surgical procedure, we calculate a target ablation (by manipulating the achieved OZ) with adequate centration and an OZ sufficient enough to envelope the achieved ablation. The net ablation map for the retreatment procedure is calculated from the achieved and target ablations and is suitable to expand, recenter, and modulate the lower-order refractive components in a retreatment procedure. The results of our simulations suggest minimal tissue removal with OZ centration and expansion. Enlarging the OZ implies correcting spherical aberrations, whereas inducing centration implies correcting coma. This method shows the potential to improve visual outcomes in extreme cases of retreatment, possibly serving as an uncomplicated and inexpensive alternative to wavefront-guided retreatments.

Paper Details

Date Published: 6 August 2014
PDF: 9 pages
J. Biomed. Opt. 19(8) 088001 doi: 10.1117/1.JBO.19.8.088001
Published in: Journal of Biomedical Optics Volume 19, Issue 8
Show Author Affiliations
Samuel Arba Mosquera, SCHWIND eye-tech-solutions GmbH & Co. KG (Germany)
Shwetabh Verma, SCHWIND eye-tech-solutions GmbH & Co. KG (Germany)


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