Non-penetrating very deep sclerectomy with a hydrophobic polymer implant in a rabbit model.

PURPOSE: The aim of the study was to evaluate the influence of an implant made of a terpolymer (PTFE-PVDF-PP) on the condition of rabbit eyes during a one year observation period. METHODS: The implant in the shape of an equilateral triangle (3 mm side length) was manufactured from a thin hydrophobic porous membrane. There were evaluated 40 eyes of 20 rabbits. The animals had non-penetrating very deep sclerectomy (NPVDS) performed, with insertion of an implant in the form of a triangular thin membrane. The control group consisted of 20 eyes where the animals had NPVDS performed without implant insertion. The evaluations included the study of the anterior part of the eye together with photographic documentation. Histopathological examination of the eyes 52 weeks after NPVDS procedure has been made. The process of wound healing was comparable in both groups. RESULTS: The evaluation of the rabbits did not reveal any acute process of intraocular inflammation. After 12 month period of observation, no statistically significant differences in the process of wound healing or status of eyes were found between the groups. An analysis of fibrous connective tissue attachment to the implant showed that its layer was not thick and did not differ significantly from the control. The procedure of very deep sclerectomy and insertion of a polymer implant were well tolerated by the rabbit eyes. CONCLUSIONS: The in vivo results indicate that the hydrophobic implant in the form of a membrane can serve as a sclera implant after further study.

Histopathological Evaluation of a Hydrophobic Terpolymer (PTFE-PVD-PP) as an Implant Material for Nonpenetrating Very Deep Sclerectomy.

PURPOSE: The purpose of the study was to assess the biocompatibility of porous terpolymer (polytetrafluoroethylene-co-polyvinylidene fluoride-co-polypropylene, PTFE-PVDF-PP) membranes as an implant material to be placed during nonpenetrating very deep sclerectomy (NPVDS). Another study objective was to determine whether the polymer membrane under investigation could be used to manufacture a new-generation implant, which would actively delay the process of fistula closure and facilitate aqueous humor drainage. METHODS: Histological response and tissue tolerance of the implant material were assessed. The study was performed on 38 eyeballs of 19 New Zealand white rabbits (19 implanted, 19 control). Histological assessment was carried out between 2 and 52 weeks after surgery. We routinely assessed inflammatory infiltrate, neovascularization, hemorrhage, and stromal edema as well as connective tissue attachment to the implant and adjacent tissues. RESULTS: At 52 weeks of observation, a statistically significant difference was revealed between the study and control groups in terms of resorptive granulation, tissue, and the inflammatory infiltrate. No features of acute inflammatory response to the implant were observed, and there was an absence of histological features of acute inflammatory infiltrates and subsidence of chronic inflammatory infiltrates and resorptive granulation over time. CONCLUSIONS: Slight fibrotic response and insignificant changes in neighboring eye tissues all indicate good tolerance to bioimplant materials. This allows for some optimism regarding the use of hydrophobic terpolymer in the construction of new intrascleral implants. However, the ultimate decision regarding its usefulness and safety in the treatment of glaucoma requires further investigation.

In vivo biocompatibility assessment of (PTFE-PVDF-PP) terpolymer-based membrane with potential application for glaucoma treatment.

The aim of the work was to evaluate the in vivo biological behaviour of polymeric membrane materials for glaucoma implants. The base material was biostable synthetic terpolymer (PTFE-PVDF-PP) with proved biocompability (PN-EN ISO 10993). The samples manufactured in the form a membrane were subjected to chemical and physical treatment to create an open pore system within the polymer matrix. As a porogenic phase biodegradable natrium alginate in a fibrous form was employed. The non-perforating deep sclerectomy technique was performed in a rabbit model. The clinical observations were made after 14 and 30 days. During the study clinical symptoms of a moderate degree were observed, and histopathological changes were typical for foreign body implantation. At the end stage of the study no significant difference in histopathological assessment was found between control and experimental group. Similarities observed in both groups and relatively mild histopathological changes in the tissue surrounding the implant indicate that the observed symptoms come from a deep scleral trauma caused by surgery, and not by the presence of the implant itself.

[Study on polysiloxane resin-based composites for bone surgery application]. / Badania nad przydatnoscia kompozytów wytworzonych z zywic polisiloksanowych dla chirurgii kostnej.

The study aimed at determination of mechanical and biological properties of three types of carbon fibers-based composites differing in matrix as potential materials for bone surgery. Three types of polymethylphenyl siloxane resins (produced by Lucebni zavody, Kolin, Czech Republic) differing with Si/C ratio were used as matrix. Carbon fibers T-300 (Torayca) were used as the reinforcement. The composite samples were manufactured by liquid impregnation of carbon roving followed by thermal curing. The resins were characterized by means of infrared spectroscopy. The strength and Young's modulus of the composite samples were determined in three-point bending test. The MTT tests were led in the presence of line KMA human macrophages and line hFOB 1.19 human osteoblasts. The results presented in this work indicate that mechanical properties of the composites are adequate from viewpoint of bone surgery requirement for load-bearing implants. The viability of macrophages cultures in contact with all examined samples was higher than 85%. The highest viability of human osteoblasts was obtained for composites based on L 901 and L 4102 resins-above 60%. The results suggest that the investigated polysiloxane-based composites are biocompatible, however their possible use as implants needs further study.