Abhijit Sinha Roy1, William J Dupps1, Cynthia J Roberts2. 1. From the Cole Eye Institute (Sinha Roy, Dupps), Cleveland Clinic Foundation, the Department of Biomedical Engineering (Dupps), Lerner Research Institute, and the Department of Biomedical Engineering (Dupps), Case Western Reserve University, Cleveland, and the Departments of Ophthalmology and Biomedical Engineering (Roberts), The Ohio State University, Columbus, Ohio, USA. 2. From the Cole Eye Institute (Sinha Roy, Dupps), Cleveland Clinic Foundation, the Department of Biomedical Engineering (Dupps), Lerner Research Institute, and the Department of Biomedical Engineering (Dupps), Case Western Reserve University, Cleveland, and the Departments of Ophthalmology and Biomedical Engineering (Roberts), The Ohio State University, Columbus, Ohio, USA. Electronic address: roberts.8@osu.edu.
Abstract
PURPOSE: To theoretically compare the corneal stress distribution of laser in situ keratomileusis (LASIK) with the stress distribution of small-incision lenticule extraction. SETTING: Cleveland Clinic Cole Institute, Cleveland, and The Ohio State University, Columbus, Ohio, USA. DESIGN: Computational modeling study. METHODS: A finite-element anisotropic collagen fiber-dependent model of myopic surgery using patient-specific corneal geometry was constructed for LASIK, small-incision lenticule extraction, and a geometry analog model with unaltered material properties from preoperative but with postoperative geometry including thickness. Surgical parameters, magnitude of myopic correction, LASIK flap thickness, and lenticule depth in small-incision lenticule extraction were varied. Two sets of models, 1 with uniform and 1 with depth-dependent material properties, were constructed. RESULTS: Stress distribution between small-incision lenticule extraction simulations and the geometry analog model were similar. In contrast, LASIK consistently reduced stress in the flap and increased stress in the residual stromal bed (RSB) compared with the geometry analog model. An increase in flap thickness or lenticule depth resulted in a greater increase in RSB stress in the LASIK model than in the small-incision lenticule extraction model. CONCLUSIONS: Small-incision lenticule extraction may present less biomechanical risk to the residual bed of susceptible corneas than comparable corrections involving LASIK flaps. Deeper corrections in the stroma may be possible in small-incision lenticule extraction without added risk for ectasia. FINANCIAL DISCLOSURES: Proprietary or commercial disclosures are listed after the references.
PURPOSE: To theoretically compare the corneal stress distribution of laser in situ keratomileusis (LASIK) with the stress distribution of small-incision lenticule extraction. SETTING: Cleveland Clinic Cole Institute, Cleveland, and The Ohio State University, Columbus, Ohio, USA. DESIGN: Computational modeling study. METHODS: A finite-element anisotropic collagen fiber-dependent model of myopic surgery using patient-specific corneal geometry was constructed for LASIK, small-incision lenticule extraction, and a geometry analog model with unaltered material properties from preoperative but with postoperative geometry including thickness. Surgical parameters, magnitude of myopic correction, LASIK flap thickness, and lenticule depth in small-incision lenticule extraction were varied. Two sets of models, 1 with uniform and 1 with depth-dependent material properties, were constructed. RESULTS: Stress distribution between small-incision lenticule extraction simulations and the geometry analog model were similar. In contrast, LASIK consistently reduced stress in the flap and increased stress in the residual stromal bed (RSB) compared with the geometry analog model. An increase in flap thickness or lenticule depth resulted in a greater increase in RSB stress in the LASIK model than in the small-incision lenticule extraction model. CONCLUSIONS: Small-incision lenticule extraction may present less biomechanical risk to the residual bed of susceptible corneas than comparable corrections involving LASIK flaps. Deeper corrections in the stroma may be possible in small-incision lenticule extraction without added risk for ectasia. FINANCIAL DISCLOSURES: Proprietary or commercial disclosures are listed after the references.
Authors: Andri K Riau; Romesh I Angunawela; Shyam S Chaurasia; Wing S Lee; Donald T Tan; Jodhbir S Mehta Journal: Invest Ophthalmol Vis Sci Date: 2011-08-05 Impact factor: 4.799
Authors: Karim Mohamed-Noriega; Kah-Peng Toh; Rebekah Poh; Deepashree Balehosur; Andri Riau; Hla M Htoon; Gary S L Peh; Shyam S Chaurasia; Donald T Tan; Jodhbir S Mehta Journal: Mol Vis Date: 2011-12-28 Impact factor: 2.367