[Experimental study a new device of scleral flap stent on filtration surgery in normal sheep]

To test the effectiveness and safety of a filtering drainage device, a scleral flap stent (SFS) made of poly methyl methacrylate (PMMA) in trabeculectomy (or filtering drainage-plasty) in sheep.

32 of normal sheep were used. Trabeculectomy was performed in both eyes and the filtering drainage device, a SFS was randomly implanted under the scleral flap in one eye. After the surgery, the intraocular pressure (IOP) was measured by Schiotz tonometer; The filtering blebs and its histopathology was examined by a slit lamp, an ultrasound biomicroscope (UBM), and electronmicroscopy.

The IOP in eyes with trabeculectomy plus SFS was statistically significant (P < 0.001) lower than that in eyes with trabeculectomy along at one month (11.38 +/- 1.20) mm Hg vs (14.05 +/- 0.93) mm Hg and at three months (11.95 +/- 1.18) mm Hg vs (15.2 +/- 1.09 mm Hg). Compared to the pre-operation, no difference in IOP was found at one month in eyes with trabeculectomy along (16.04 +/- 1.02) mm Hg vs (14.05 +/- 0.93) mm Hg. The filtering bleb was lasted more than 3 months in eyes with trabeculectomy plus SFS while existed only one month in eyes with trabeculectomy along by both slit lamp and UBM examination. The fibroblastic proliferation of filtering pathway and scar formation was found at one months post-operation in eyes with trabeculectomy along, however, the fibroblastic proliferation and the scar formation were found at three months and at six months after surgery in eyes with trabeculectomy plus SFS, respectively, by a light and electronmicroscopy examination. Tissue compliance was good and no elimination occurred. No toxic or adverse effects were observed in the following year post-operatively.

SFS is a safe and effective newly designed filtering drainage device in lowering IOP when performed together with trabeculectomy.