Endothelium-descemet membrane strength after trephination

Purpose. To assess the strength of the endpthelium-Descemet membrane after pre-Descemet trephination to implant a non-penetrating keratoprosthesis. Methods. 53 cadaver eyes were used. After epithelium removal with ethanol, the corneal thickness was measured by ultrasonic pachymetry (Pachette, DGI Technologies). A 7 mm diameter (Ø) trephination was achieved with a Hanna trephine set at 80% thickness. A delamination was made with a smooth blade to remove the remaining stroma, Three parameters were recorded versus intraocular pressure (IOP) measured with a IOP monitor (Ophthalmic Surg 18: 371-374, 1987). 1: Radius of curvature (RC) of the delaminated zone compared to RC of non-trephined eyes (SK-1 keratometer, Canon); 2: Horizontal and vertical Ø of the trephined zone (Digital caliper, Mitotuyo); 3: Vertical motion of the endothelium-Descemet measured with a 100x CCTV microscope. Results. 1: There was no significant difference in RC between trephined and non-trephined eyes; 2: The average Ø change of the 7 mm trephination was of 157 μm. The Ø did not change with time, even after 15 minutes at 500 mmHg; 3: The relative vertical motion of the endothelium-Descemet was 120μm. The endothelium-Descemet blew-up when the IOP reached 1000 mmHg. Conclusion. The strength of the endothelium-Descemet is sufficient for safe implantation of a non-penetrating keratoprosthesis.