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Mean curvature mapping: application in laser refractive surgery

Tang, Maolong
http://rave.ohiolink.edu/etdc/view?acc_num=osu1094593446

Abstract Details

2004, Doctor of Philosophy, Ohio State University, Biomedical Engineering.
Every year, there are millions of people going through corneal refractive surgery. Laser in-situ keratomileusis (LASIK) is the most commonly performed procedure. Although most LASIK patients found the visual outcome satisfactory, LASIK is not perfect in all respects. One area that needs improvement is pre-surgical screening for keratoconus. Pre-surgical screening for keratoconus is important because it can lead to severe keratectasia after LASIK. Currently, identifying mild cases of keratoconus is still a challenge. In this study, we exploited one of the modern representations of corneal topography, called mean curvature mapping, as a more sensitive method to detect subtle shape abnormalities. We found that mean curvature mapping may be a better way to quantify the parameters of keratoconus such as location of cone peak, cone magnitude, and cone diameter. Another area that needs improvement is reduction of surgically-induced aberrations, which may lead to uneven quality of visual in dim light and glare. Post-surgical epithelial remodeling plays a very important role in the unexpected difference between the actual and intended results of laser ablation, which eventually leads to post-surgical corneal aberrations. In this study, we devised a mathematical model of epithelial remodeling based on an epithelial transport theory. This model predicts that the epithelial thickness is modulated by corneal surface mean curvature and this produces a surface smoothing effect which occurs after LASIK. The model agrees quantitatively with observed epithelial thickening in the center of a myopic ablation zone and in the periphery of a hyperopic ablation zone. The model also successfully predicts the induction of positive spherical aberration after myopic ablation and negative spherical aberration after hyperopic correction. The mathematical model was used as the basis to design ablation patterns that compensate in advance for the expected corneal surface smoothing response. Theoretically, this ablation algorithm can be programmed to compensate for all orders of surgically-induced aberrations due to corneal epithelial healing, which could potentially improve the quality of vision. We called this the “Advanced Healing-Adjusted Ablation” (AHAA) algorithm.
David Huang (Advisor)
Engineering, Biomedical
CORNEAL; ablation; keratoconus; aberrations; MEAN CURVATURE; Astigmatism; correction

Recommended Citations

Citations

  • Tang, M. (2004). Mean curvature mapping: application in laser refractive surgery [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1094593446

    APA Style (7th edition)

  • Tang, Maolong. Mean curvature mapping: application in laser refractive surgery. 2004. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1094593446.

    MLA Style (8th edition)

  • Tang, Maolong. "Mean curvature mapping: application in laser refractive surgery." Doctoral dissertation, Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1094593446

    Chicago Manual of Style (17th edition)

osu1094593446
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© 2004, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.