Abstract
Abstract: :
Purpose:To assess the tissue reaction and fibrous capsule formation after implantation of different synthetic materials selected for novel glaucoma implant design. Methods:Adhering to ARVO guidelines regarding experimental animal use and care, 12 NZW rabbits received 1, 2, 3 or 4 different materials in the subtenon space between the extraocular muscles. The materials were (1) hydrophobic PDMS (Baerveldt glaucoma implant, Pharmacia) (control I); (2) ePTFE 3um (Zitex USA, control II), (3) ePTFE (NTF, Japan) untreated and surface treated with 193nm excimer laser radiation in a solution containing Boron to render the surface hydrophilic with fluence of 7, 10, 15, 20 and 25mJ/cm2; (4) ePTFE (Mitex USA) treated at 10, 15, 20 and 25mJ/cm2; (5) hydrophilic pHEMA-MMA26 (Corneal SA, France), (6) pHEMA-MMA34 (Corneal SA, France), (7) pHEMA-VP75 (Corneal SA, France), and (8) hydrophobic PEA-PEMA (Acrysoft, Alcon USA). The animals were examined post surgery at POD 3 and 7, and weekly thereafter. All were euthanized at 12 weeks for histopathology analysis. Results:Postoperative course was uneventful. None of the animals showed signs of inflammatory reaction at the slit-lamp. Histology findings show variable chronic inflammatory cells infiltrates, composed of lymphocytes, histiocytes and giant cells presented in all materials except the hydrogels where the reaction was very mild without giant cells or histiocytes. Variable amounts of fibrous cellular tissue surrounding the implants with the smallest amount in the hydrogel material as well. The amount of inflammation and fibrosis was graded at the light microscope using a three-tier classification system (mild, moderate and severe). Measurements of de novo fibrotic tissue mass is ongoing. Microscope observation shows the hydrophobic PDMS being worse and hydrogels being best tolerated, with very few inflammatory cells and only the shadow of a fibrous capsule.. Conclusions: Hydrophilic polymers may be useful in the design of smaller and more biocompatible glaucoma implants.. Support: Florida Lions Eye Bank; Research to Prevent Blindness; Henri and Flore Lesieur Foundation.
Keywords: 631 wound healing • 474 microscopy: light/fluorescence/immunohistochemistry • 574 sclera