Congratulations to Elahi and colleagues in describing a unique and revolutionary method in controlling chronic hypotony in Baerveldt tube (BVT) surgery. The Eyewatch device is the first truly adjustable glaucoma drainage device. The magnetically controlled compression wheel within the Eyewatch device allows external, clinic-room adjustment to the flow of the device and titration of intraocular pressure. The initial result of its efficacy as a primary tube-shunt surgery was recently published and larger multi-center study result would follow in the next year. Although not every patient undergoing glaucoma tube surgery would require the precise control of flow that the Eyewatch has to offer, the ability to potentially reduce or eliminate hypotony in tube surgery has to be described as a major surgical advancement. We have debated for years between the choice of a valved and non-valved drainage device; even with the twice-demonstrated IOP superiority of the BVT against Ahmed valve in ABC and AVB studies, many surgeons continued to champion the Ahmed based on its safety and its reduced risk of hypotony.
The Eyewatch device is the first truly adjustable glaucoma drainage device
This case report yet again highlighted the issue with BVT and hypotony. As the author describes, many methods have been reported to combat chronic hypotony; it often starts with viscoelastic injection in the anterior chamber, followed by insertion of intralumenal stent in the anterior chamber or tying of the tube with nylon sutures. All these interventions, in my humble opinion, can be best described as 'educated guess work' in terms of the amount of viscoelastic required, size and length of the intraluminal stent or the tightness of the tube tie. Any subsequent IOP increase or spikes have to be cushioned with medications or laser suture lysis (hoping not to over-do it resulting in hypotony again). Fortunately, this case report has described one of the most sensible way to titrate a non-titratable BVT, by retro-fitting an Eyewatch to it. This allows fine control of flow in those few patients who have brittle inflow-outflow balance and hopefully finally rid of the curse of chronic hypotony. I congratulate the authors for their imaginative approach to dealing with a well-known BVT complication.