The VisiPlate is an ultrathin, multichannel, nonfibrotic aqueous shunt, which can have significant advantages in glaucoma surgery.
It shunts aqueous humor from the anterior
chamber through a network of open microchannels to the subconjunctival space.
VisiPlate’s metamaterial features a highly
biocompatible alumina plate coated with Parylene C. The device has a 400-nm aluminum oxide plate
coated with a 2-µm-thick layer of Parylene C.
It is corrugated into a pattern of
networked microchannels, forming a hexagonal honeycomb.
The network of highly tunable rectangular
microchannels rather than a large single-lumen tube provides better stability
to aqueous outflow. The VisiPlate design represents a unique approach to
lowering IOP; the numerous microchannels in the device enable slow and
controlled outflow and provide a multitude of pathways for redundancy.
Slow outflow can create a diffuse,
low-lying bleb that avoids tension and results in greater patient comfort than
an elevated bleb.
Additionally, a controlled reduction of IOP
minimizes the risk of early suprachoroidal hemorrhage.
VisiPlate’s thin profile is designed to
limit peri-device flow and provide greater comfort and better aesthetics for
the patient, with less risk of microtraumas from eyelid movement. Additionally,
the nonfibrotic nature of the device minimizes foreign body response and has
the potential to be effective without antifibrotic agents.
The composite structure of the VisiPlate is
flexible and allows the device to conform to the curvature of the globe.
A version of VisiPlate being evaluated in
early feasibility trials is approximately 5 mm wide and 8 mm long.
The implantation of the device is simple,
without the need for patch grafts and gonioscopes. A scleral tunnel is created after
a peritomy and the end of the device is inserted into the anterior chamber. The
device is secured to the sclera. Antifibrotic agents can be used, according to
the surgeon’s preference.
In a rabbit study by Kao et al, the VisiPlate
demonstrated statistically significant (p<0.05) intraocular pressure (IOP)
lowering of 20-40% compared to baseline at each timepoint over three months in nine
implanted eyes.
A recent human VisiPlate study, known as
the VITA trial, initially enrolled 15 patients and currently has 9-month data
on 6 of those patients. On average, those with VisiPlate experienced a 46% drop
in IOP (from 24 mmHg at baseline to 12.3 mmHg), and a reduction in average
medication use from 2.1 medications at baseline to 0.7 medications.
The multichannel design provides several
potential advantages over a tubular design by minimizing the risk of
postoperative hypotony, avoiding peri-device flow, and diffusing aqueous in all
directions in the subconjunctival space to form and sustain a low-lying bleb.
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