Robotic Biological Microfistula Implantation for Glaucoma Drainage Surgery (A Preliminary Report)

Abstract

Abstract: : Purpose: To develop a novel anterior chamber approach to drainage surgery aimed at creating a precisely controlled and permanent drainage channel between the anterior chamber and the subconjunctival space. Methods: A bio-engineered microfistula tube (cross-linked gelatin) was implanted via the anterior chamber through the trabecular meshwork and the sclera to create a drainage channel to the subconjunctival space. The microfistula was designed to absorb over a period of months. Accurate implantation of the microfistula was achieved by the use of a specially constructed ultra microsurgical system. This novel surgical approach was tested in 53 normal rabbits and 20 monkeys following laser treatment to elevate IOP. Dynamic monitoring of fluorescein drainage from the anterior chamber using digital video techniques assessed the functional status of the drainage channel. IOP was also monitored as a function of implantation time. The extent of microfistula absorption and tissue reaction were assessed histologically. Results: The anterior chamber remained well formed after surgery. The implanted microfistula tubes were well tolerated and absorbed in 7-9 months, leaving behind a patent drainage channel with minimal scarring. With successful implantation, functional drainage pathways were not only evident between the anterior chamber and the bleb, but direct drainage pathways between the bleb and the aqueous veins and/or lymphatics were present as early as two weeks after surgery. Drainage was maintained for the entire follow up period (in excess of 12 months in some cases). Conclusion: This novel micro drainage surgery produces long lasting drainage pathways with minimal damage to ocular tissues. The avoidance of conjunctival injury at the implantation site appears to avoid the complications of conjunctival scarring which is a common problem in more conventional drainage surgery. Implantation of microfistula drainage devices via the anterior chamber may provide a safer, more widely applicable technique for drainage surgery in glaucoma.

Keywords: anterior segment