The goal of glaucoma surgery is to control intraocular pressure (IOP) to prevent progression of vision loss. One way to achieve this, after exhaustion of medication options, is by use of glaucoma drainage devices. The Baerveldt Glaucoma Implant (BGI; Abbott Medical Optics, Inc., Santa Ana, CA) is one of the more commonly used devices. The BGI does not have a valve restricting aqueous flow in the early period after implantation. Thus, either an obturator that is removed postoperatively or tube ligature must be used to prevent hypotony until an adequate bleb has formed. However, during flow restriction, IOP control is difficult, potentially resulting in IOP spikes above target and necessitating the use of IOP-lowering medications. Also, an additional step is required to remove flow restriction, increasing risk to the patient and cost.
The eyeWatch is a potentially useful device for patients with refractory glaucoma who require a nonvalved glaucoma implant for glaucoma control
Roy et al. analyzed the use of the eyeWatch device, a device implanted with the BGI that allows for adjustable flow resistance. The eyeWatch allows variable compression of the tube draining aqueous from the anterior chamber using a magnetic rotor and is adjusted with an external control unit, the eyeWatch Pen, containing a magnet and compass to read the rotor position. Fifteen eyes from 15 patients were included in this study. Patients included were 18 years or older with refractory glaucoma after previous filtering surgeries, with an IOP > 20 mmHg on maximally tolerated medical therapy. Patients with secondary glaucomas or related previous eye surgeries were excluded. BGIs with surface areas of either 250 or 350 mm2 were implanted. Complete success was defined as IOP ≤ 18 or ≥ 6 mmHg and IOP reduction of 20% with no IOP-lowering medications at last visit. Overall success was the same except with or without IOP-lowering medications. Additional surgery requiring a trip to the operating room was defined as a failure, but procedures at the slit lamp were not considered reoperation (e.g., bleb needling, paracentesis, etc.).
IOP decreased from 26.2 ± 6.8 mmHg at baseline to 11.9 ± 2.8 mmHg at 12 months, a 54% decrease (P < 0.001). Mean number of glaucoma medications also decreased from 3.0 ± 0.7 at baseline to 0.8 ± 0.9 at last visit, a 73% reduction (P < 0.001). Mean endothelial cell count and central corneal thickness were not different at baseline and last visit. Best-corrected visual acuity also remained stable. The failure rate was 7%, and four eyes had complications, two conjunctival wound leaks and two choroidal detachments. Three resolved spontaneously, with one wound leak requiring surgical revision. No slit-lamp interventions were required. Five patients with the device underwent magnetic resonance imaging (MRI) with no complications during or after imaging, but this may vary depending on the size of the MRI magnet.
The eyeWatch is a potentially useful device for patients with refractory glaucoma who require a nonvalved glaucoma implant for glaucoma control. Further and larger studies will be necessary to investigate efficacy and safety fully.