A New Noninvasively Adjustable Glaucoma Drainage Device

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.