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I.J. Dualan, K.T. Doan, K.M. Ramonas, D. Gore, S.G. Kikolski, P.A. Asbell; Conductive Keratoplasty and Induced Astigmatism in Enucleated Porcine Eyes . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2576.
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Purpose: To determine the effect of conductive keratoplasty (CK) on astigmatism in enucleated porcine eyes. Methods: CK, a technique using radiofrequency waves to shrink corneal stromal collagen for the treatment of hyperopia, was applied in four different patterns to the corneal periphery of twelve enucleated porcine eyes to induce astigmatism. The keratoplast tip was lengthened for use in porcine eyes to 880um. Energy was adjusted appropriately to visualize treatment marks. Each eye was mounted onto a suction board, after which intraocular pressure by Shiotz tonometry was titrated to 20mmHg +/- 1mmHg. Eyes were selected based on the following criteria; minimal astigmatism (cylinder ≤ 1.50D) and an average of five consistent automated keratometry (K) readings ranging from 38.00-43.00D. Corneal thickness by optical pachymetry was measured and recorded. CK was applied along the steepest meridian in the predetermined treatment zone with a diameter of 6mm, 7mm, 8mm or all combined to induce an increased astigmatism in the same axis. Repeated measurements of cylinder, axis and average K readings were again recorded and corresponding changes were noted. Results: Treatment spots applied at 6mm zone showed a consistent change in astigmatism. Spots at 7mm and 8mm showed an unpredictable or no change in the amount of astigmatism. Combined spots at 6mm, 7mm and 8mm had a slightly higher induction of astigmatism. All cylinder changes made were significantly close to or were at the axis where treatment was applied. Conclusion: Conductive keratoplasty with regards to astigmatism in enucleated porcine eyes showed: 1) a more consistent effect in the smaller treatment zone, 2) a greater effect when treatment spots were applied in combined treatment zones and 3) all increases in induced cylinder matched the treated axis. This pilot study demonstrates that enucleated porcine eyes can be used as an animal model in the application of CK. Further use of this model will be pursued to evaluate the use of CK to treat the induced astigmatism. Use of this model may help initiate a nomogram for the treatment of human corneal astigmatism. View OriginalDownload SlideView OriginalDownload Slide
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