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Ellen H. Koo, Harry G. Glen, Michael Berry, Paul J. Botelho; Histologic Corneal Changes Following Optimal Keratoplasty (Opti-K) Treatment of Cadaver Eyes. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5789.
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The Optimal Keratoplasty (Opti-K) system using laser thermal keratoplasty with a sapphire applanation window/ suction ring accessory (SAWSR) to protect the corneal epithelium is a novel technique to correct hyperopia. We report histologic findings in 4 cadaver eyes treated by Opti-K with and without the SAWSR.
Four cadaver eyes from 2 human donors were obtained. One eye from the first donor received Opti-K treatment with the SAWSR at 60mJ and was labeled Human-1; the fellow eye received Opti-K treatment without the SAWSR at 59mJ and was labeled Human-2. One eye from the second donor received Opti-K treatment with the SAWSR at 59 mJ and was labeled Human-3; the fellow eye received Opti-K treatment without the SAWSR at 59 mJ and was labeled Human-4. The corneas were prepared in Hematoxylin and Eosin, Alcian Blue and Periodic acid-Schiff stain. All slides were read by the same pathologist, Nora Laver, M.D.
All eyes showed anterior stromal thermal reaction with mild involvement of Bowman’s layer and sparing of the endothelial layer. Human-1 and Human-2 demonstrate bullae formation and degeneration of the basal epithelial cells. Human-3 showed less alteration of the basal epithelial cells and a smaller upper stromal heat affected zone (HAZ) compared to Human-4. Human-4 had a larger area of HAZ with bullae formation as well as marked stromal edema. Neither of these changes was observed in Human-3.
Photothermal treatment using the Opti-K device without the SAWSR resulted in large, obvious areas of laser HAZ with bullae formation and alteration of the basal epithelial cells, while the use of the Opti-K with the SAWSR resulted in a markedly smaller upper stromal HAZ as well as an absence of stromal edema and bullae formation, as demonstrated by the comparison of Human-3 and Human-4.Comparison of Human-1 and Human-2 showed equal amount of epithelial damage. It is possible that the epithelium was damaged prior to treatment, as this layer is most vulnerable to trauma during harvest and transport, and unfavorable preservation conditions. In addition, the protective properties of the SAWSR may be limited by the energy setting. Human-1 received treatment with the SAWSR at 60 mJ; at this setting, the sequelae of photothermal treatment were similar to Human-2, which received treatment without the SAWSR at 59 mJ. The protective effects of the SAWSR may be lost at settings beyond 59mJ. Further in-vivo and clinical studies are needed to study the safety and long-term efficacy of the Opti-K system.
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