Abstract
Purpose :
Similar to traditional glaucoma surgery, microinvasive bleb surgery (MIBS) involves the creation of a filtering bleb to shunt aqueous humor from the anterior chamber to subconjunctival space. In this study, we investigate the bleb histopathology of a novel titratable aqueous shunt device and compare findings with a commercial pediatric aqueous shunt in post-mortem New Zealand White (NZW) rabbit eyes from a separate study.
Methods :
The titratable aqueous shunt was implanted via a fornix-based conjunctival flap dissected in the supranasal quadrant in six NZW rabbits (12 eyes in total) with adjunctive mitomycin-C (0.4 mg/mL soaked sponges placed for 3 minutes). Eyes were enucleated at Day 20 (2 eyes), Day 22 (2 eyes) and Day 32 (8 eyes). The anterior and posterior sections of the globes were examined for signs of inflammation and fibrosis and then compared with those of two left rabbit globes from two NZW rabbits implanted with the commercial aqueous shunt for 30 days. All devices were removed prior to histologic evaluation.
Results :
In the commercial aqueous shunt group, 2 of 2 eyes had a thin fibrous pseudocapsule overlying the device with no signs of fibroblastic proliferation. In both eyes the site where the tube of the device entered the anterior chamber was visible at the peripheral cornea. In the titratable aqueous shunt group, there were no signs of fibroblastic proliferation adjacent to the bleb or device entrance site at the limbus in 11 of 12 eyes. The bleb space, visualized in all eyes with separation of the episcleral tissue from the sclera, ranged in size from shallow and diffuse to large. One eye had signs of fibroblast proliferation adjacent anteriorly and posteriorly to the bleb, which was moderate in size with a small surrounding fibrous layer. There were no signs of an inflammatory cell reaction in any eye.
Conclusions :
Historically, few studies compare the histopathological features of MIBS devices with those of traditional glaucoma drainage devices. We found the novel titratable aqueous shunt to be comparable to the tube shunt in their lack of inflammatory cell reaction and scarring. An early feasibility clinical trial in humans is currently in progress.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.