Abstract
Purpose :
Thickening of the fibrous capsule formed around a glaucoma drainage device impedes aqueous outflow and causes failure of these devices over time. The material used as the end plate has been shown to be a major modifiable factor for inflammatory response of the bleb. We aimed to study the histopathological characteristics of the fibrous capsule formed around a novel biodegradable glaucoma drainage implant.
Methods :
8 New Zealand white rabbits, weighing between 2 to 3 kg were implanted with an indigenously designed biodegradable glaucoma drainage device made of Oxidized Regenerated Cellulose in the sub-tenon’s space and the silicon tube inserted into the anterior chamber. Rabbits were euthanized in 2 batches of 4 each at intervals of 1 month / 3 months and their enucleated eyes subjected to histopathological and immunohistochemical studies to determine the healing response.
Results :
One month post implantation, the biodegradable material produced a significant foreign body type of reaction evidenced by exuberant infiltration of macrophages, lymphocytes and multinucleated giant cells. Early fibrogenesis was recognized by myofibroblast trans-differentiation on α-SMA (alpha-smooth muscle actin) immunohistochemistry, but no well-established fibrosis (stained with Masson's trichrome) was observed. No fibrous capsule formation was noted at one month in any of the four eyes. Oxidized regenerated cellulose was seen to persist in small amounts even at three months on polarizing microscopy, but there was a marked decrease in the inflammatory reaction around it. Myofibroblasts decreased in density with the formation of small wisps of fibrosis which was scanty and disorganized.
Conclusions :
The type of healing response against a biodegradable glaucoma drainage device is more favorable towards forming a diffuse permeable filtering matrix which could produce blebs that are poly-cystic and may be diffusely filtering, though the same requires further functional validation over a longer period of time.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.