Abstract
Purpose :
To examine the efficacy of the recently commercial model of the anterior to back (A2B) shunt (AJL, Bilbao, SP) in lowering intraocular pressure (IOP) after failure of all other IOP-lowering therapies (including antimetabolite filtering and standard tube shunt procedures).
Methods :
Design: Retrospective quality assurance chart review
Inclusion: all individuals who had undergone A2B shunt placement from Jan-Oct 2019 after having failed all other IOP-lowering therapies. Change in IOP and number of medications used was assessed using paired t-test.
Results :
16 eyes of 13 patients were assessed (mean age 57.21; 7M6F). A mean of 2.7 prior incisional glaucoma procedures had been performed on each eye without sustained success, with mean IOP 34.4±2.9mmHg on a mean of 2.2 IOP-lowering drops. At 1, 7, 30, 90, and 180 days after surgery, 100%, 86%, 84%, 100%, and 100% of patients maintained an IOP ≤ 21 mmHg, respectively. At these same time intervals IOP dropped from the baseline value of 34.4±2.9mmHg to 7.3±1.4 (-27.1mmHg, -78%), 14.3±2.5 (-20.1mmHg, -58%), 14.6±1.8 (-19.8mmHg, -57%), 15.2±1.7 (-19.2mmHg, -55%), and 16.8±1.2 (-17.6mmHg, 51%) respectively (p < 0.001). Change in medication at 30, 90, and 180 days dropped from baseline of 2.52 to 0.29±0.16, 0.07±0.07, and 0.11±0.11, respectively (p<0.0001). (Fig. 1)
Conclusions :
The A2B shunt is a silicone glaucoma device designed by Dr. William E Sponsel, that without the need of a bleb, drains aqueous humor from the anterior chamber to the retrobulbar space. The anterior tubing is identical to that used in standard Ahmed, Baerveldt or Molteno implants, but rather than a plate it has a poly-fenestrated large-bore posterior tube that delivers aqueous into the retrobulbar space. The surgical procedure involves a similar protocol to traditional tube shunts but requires approximately 1/3 of the surgical time because it obviates any need for posterior dissection or scleral fixation of a plate. The risk of aqueous leakage or tube/tutoplast exposure is also eliminated because intrinsic properties of retrobulbar fat create a one-way valve system with no risk of aqueous reflux to the limbus. Prior studies have indicated that redirecting aqueous humor into the retrobulbar space is followed by the formation of a retrobulbar lymphatic-like network of micro-canaliculi between adipocytes resulting in a highly effective means of lowering IOP (3 ref upon request).
This is a 2020 ARVO Annual Meeting abstract.