Design and validation of a telemetrically drived implantable glaucoma drainage device

Glaucoma is one of the leading cause of irreversible blindness in the world and it usually occurs when the pressure inside the eyes gradually rises, permanently damaging the optic nerve. Medications and filtering surgery are two possible therapies available for patients suffering from this disease. In the same perspective, glaucoma drainage devices allowing a better outflow of the aqueous humor have been developed to address most of the problems present with the classic surgical techniques. However none of the implants currently available on the market have been able to date to address the problems related to the postoperative hypotony, the long-term fibrosis formation as well as the requirements to adjust filtration to the specific needs of the patients. In this context a new adjustable glaucoma drainage device is being currently developed that allows a continuous control of the outflow resistance. Its optimization and validation depends on previous outflow facility and resistance measurements. Thus 5 enucleated eyes from white New-Zealand rabbits have been perfused with a saline solution using a micropump before surgery and after implantation of a microtube (V-50 ${Ex-PRESS}^{TM}$ ). The resulting outflow facilities were respectively 0.35 and 1.31 $\mu$ l/min/mmHg when the compliance was not altered by the filtering surgery and the microtube insertion. The tube composing the device showed a resistance equivalent to $23\times{10}^{-3}$ mmHg/ $\mu$ l/min with an internal diameter equal to 250 $\mu$ m. From a theoretical point of view the linear relation between the adjustment of the resistance and the intraocular pressure has been verified. This relation was obtained by crushing the tube with a disc acting within the implant. The energy required to crush the tube was estimated to be at least ${10}^{-6}$ Nm. These results support the idea that the construction of an adaptable glaucoma drainage device is possible opening the doors to an automatically driven sensor device

A New Noninvasively Adjustable Glaucoma Drainage Device

Adan Villamarin

Glaucoma is an irreversible disease affecting the eye, leading to progressive loss of vision and eventually to total blindness. It is often related to high intraocular pressure (IOP), which results from increased outflow resistance to aqueous humor. The first line of treatment to stop or slow down the progression of the disease is based on medication, but when this fails one has to resort to invasive methods, such as filtering surgery. Filtering surgery, including drainage implants or aqueous shunts, aims in reducing intraocular pressure by creating an additional outflow conduit to aqueous humor. However, even if filtering surgery is effective in lowering intraocular pressure, it is often associated with several complications that could potentially lead to further damages impairing the sight. The origin of most complications can be traced to a fundamental mechanism: poor flow control. Among others, hypotony (IOP < 5 mmHg) is one of the most frequent complications after glaucoma filtering surgery. Hypotony is a consequence of very low outflow resistance, leading in some severe cases to anterior chamber flattening or choroidal detachment, among others. Consequently, modifications to glaucoma drainage devices and new surgical techniques were developed to minimize the rates of early post-operative hypotony. Unfortunately, these techniques are poorly reproducible and not fully predictable. At present, there are no real alternatives at hand to clearly improve the success rate of filtering surgery outcomes. In view of the aforementioned problems related to filtering surgery, a new glaucoma drainage device has been developed. This draining implant has the same function like any of the current drainage devices but with the specific additional feature of an adjustable resistor to the aqueous humor egress. The device is non-invasively adjustable allowing for a non-traumatic change of the resistance during the entire post-operative period. In vitro tests realized on enucleated rabbit eyes and in vivo tests on rabbits have shown the efficacy of the implant in reducing the pressure by selectively adjusting the resistor. Biocompatibility tests have also been performed to ensure the safety of the device for human use. The ease of use and the reproducibility of the measurements indicate that the novel implant can be potentially of great utility in filtering surgery, offering great flow control, reducing complications rates and leading to better clinical outcomes.

EPFL2014

Initial Clinical Results of the eyeWatch: a New Adjustable Glaucoma Drainage Device Used in Refractory Glaucoma Surgery

Stéphane Bigler, André Mermoud, Sylvain Roy, Nikolaos Stergiopulos, Constantinos Stergiopulos, Adan Villamarin

Precis: In this study, we report clinical results after implantation of an adjustable glaucoma drainage device. The intraocular pressure (IOP) profile was efficiently controlled postoperatively as the resistance to aqueous humor outflow was finely adjusted. Purpose: The main purpose of this study was to evaluate the safety and efficacy of the new adjustable glaucoma drainage device eyeWatch used in conjunction with a Baerveldt glaucoma implant in refractory glaucoma. Patients and Methods: This was a multicentric, prospective, noncomparative clinical trial. Patients older than 18 years of age suffering from refractory glaucoma after failed surgeries, with IOP of >= 20 mm Hg, in whom a further glaucoma procedure using an aqueous shunt was planned, were enrolled in this study. The primary outcome was the success rate, defined as an IOP 20% from baseline, IOP >= 6 mm Hg. Secondary outcomes were mean IOP, visual acuity, number of antiglaucoma medications, number, and type of complications. Results: Fifteen patients were included. The mean follow-up time was 15.6 +/- 3.5 months. The mean baseline IOP decreased from 26.2 +/- 6.8 mm Hg before surgery to 11.9 +/- 2.8 mm Hg at 12 months (P

LIPPINCOTT WILLIAMS & WILKINS2019

A New Noninvasively Adjustable Glaucoma Drainage Device

Adan Villamarin

EPFL2014