von Fischern T, Langefeld S, Yuan L, Völcker N, Reim M, Kirchhof B, Schrage N F
Interdisciplinary Centre of Clinical Research (IZKF) BIOMAT, Technical University of Aachen, Germany.
Int J Artif Organs. 1999 Jan;22(1):52-7.
None of the keratoprostheses available today is absolutely successful in the long term, neither the problems of extrusion, retroprosthetic membrane formation and intraocular pressure rise are yet solved. A new type of keratoprosthesis is required which can show improved ingrowth characteristics and allow intraocular pressure measurements. In order to possibly meet the above mentioned requirements we developed a flexible silicone keratoprosthesis with scleral fixation and chemical surface modification.
The one-piece keratoprosthesis is made of silicone rubber. Its optical zone has a diameter of 11 mm and is 0.3 mm thick. The surface-modified haptic consists of a scleral rim and eight branches for scleral fixation. A ridge at the back of the keratoprosthesis fitting into the trephination hole shall avoid leakage and retroprosthetic membrane formation. Optical and mechanical qualities are characterised by tensile tests, spectrophotometry and topography.
A method for keratoprosthesis-production was established. The optical quality of the device was improved by submicron lathing of the mould. Spectrophotometry showed high visible and ultraviolet light transmission of the silicone. Mechanical tests with silicone samples revealed high tensile strength and elongation at break. The mechanical properties were not impaired by surface modification.
The production of a flexible silicone keratoprosthesis with high optical and mechanical properties was established. Its use both for the treatment of permanently opacified corneas and as temporary keratoprosthesis seems to be possible.
目前可用的人工角膜假体从长远来看都并非绝对成功，假体挤出、假体后膜形成和眼压升高的问题仍未解决。需要一种新型人工角膜假体，它应具有更好的组织长入特性并能进行眼压测量。为了可能满足上述要求，我们开发了一种具有巩膜固定和化学表面改性的柔性硅胶人工角膜假体。
一体式人工角膜假体由硅橡胶制成。其光学区直径为11毫米，厚0.3毫米。表面改性的触觉部由巩膜边缘和八个用于巩膜固定的分支组成。人工角膜假体背面的一个脊与环钻孔相适配，应可避免渗漏和假体后膜形成。通过拉伸试验、分光光度法和表面形貌分析对光学和机械性能进行表征。
建立了一种人工角膜假体的生产方法。通过对模具进行亚微米车削提高了该装置的光学质量。分光光度法显示硅胶具有高可见光和紫外线透过率。对硅胶样品进行的力学测试显示出高拉伸强度和断裂伸长率。表面改性并未损害机械性能。
已成功生产出具有高光学和机械性能的柔性硅胶人工角膜假体。它似乎可用于治疗永久性角膜混浊以及作为临时性人工角膜假体。
