Biodegradable material for glaucoma drainage devices - A pilot study in rabbits.

Purpose: To study the morphological and histological characteristics of the fibrous capsule formed around a novel biodegradable glaucoma drainage device (GDD) implant made of oxidized regenerated cellulose (ORC) after 1 and 3 months of its implantation.

Methods: It was a prospective, interventional, preclinical experimental study using New Zealand white rabbits. All animals underwent GDD implantation with a novel biodegradable device. The device's body was made of ORC and attached to a silicone tube, connecting the body to the anterior chamber. Histopathology (hematoxylin and eosin/Masson's trichrome staining) and immunohistochemistry (Alpha-Smooth Muscle Actin expression) characteristics of the bleb formed around the novel device were noted at 1 and 3 months.

Results: One month post implantation, the biodegradable material produced a significant foreign body type of reaction evidenced by the exuberant infiltration by macrophages, lymphocytes, and multinucleated giant cells. The granulomatous response subsided by 3 months with disorganized collagen deposition on Masson's trichrome staining. The silicone tube was an internal control, and histopathology demonstrated well-organized collagen deposition around it at 3 months. Immunohistochemistry for α-smooth muscle actin also demonstrated more myofibroblast transformation at the site of the tube than the biodegradable implant.

Conclusions: Our results indicate that the tissue response around a biodegradable GDD was different from the response to conventional devices. A diffuse, loose vascularized mesh was observed to develop, which may be more compatible with sustained IOP control over a longer period, in contrast to the usual thick and dense capsule formed around the non-biodegradable devices.