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SL Kaminski, e Lacombe, b Duchesne, v Fernandez, p Lamar, w Lee, f Manns, e Alfonso, j-M Parel; Supradescemetic Keratoprosthesis (SD-KPro): A Novel Design . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2993.
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Purpose: To assess feasibility, mechanical stability and biocompatibility of a new SD-KPro. Methods: The mesoplant optical zone (8mm radius of curvature, 4.5mm diameter, 450µm thick) has a conical base with 100µm thick 1.25mm wide annular skirt with 18 perforations for tissue ingrowth and nutrient transfer. Four materials were tested: hydrophobic PMMA and hydrophilic pHEMA-MMA26, pHEMA-MMA34 and pHEMA-NV75 (number =%H2O). In 58 adult NZW rabbits, after a superior limbal incision, Descemet's membrane was identified and a centripetal delamination performed. A custom-made shield was inserted and the trephination done with 3.98 or 3.51 mm handheld vacuum trephines. The SD-KPro was either inserted through the trephination opening or via the delaminated tunnel. Antibiotic eye drops were administered tid for 3 days postop. The eyes were daily examined at the slit-lamp for the first week and weekly thereafter. Animals were euthanized only in cases of impending extrusion, massive inflammation or other adverse reactions. Results: With our technique, accurate delamination was easy, a 90 % average depth achieved, and only 8 perforations occurred intraoperatively. Implantation was easy in all cases and the new SD-KPro didn't require sutures or glue for fixation. In this ongoing study, overall retention time (RT) for all 4 materials is 89.7 ± 73.9days (range, 7 to 276days) with mean RTs of: PMMA =131 ± 93.7days (max 253), pHEMA-MMA26 = 76.6 ± 41.6days (max 230), pHEMA-MMA34 =160.7 ± 109.2days (max 276), HEMA- NVP75 =70.8 ± 30.0days (max 162). Histology of 9 excised specimen (between 3 to 50 weeks postop) showed epithelial down growth surrounding the implants and a rarification of the epithelium close to the optic and over the annular skirt. Conclusion: The new SD-KPro design in conjunction with the new delamination technique improved mechanical stability and retention time. The pHEMA-NV75 was found opto-mechanically similar to, and highly biocompatible with, the cornea.
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