A team of researchers in the Department of Biomedical Engineering, led by Aaron Fleischman, PhD, is developing an “intelligent” contact lens to measure intraocular pressure (IOP) throughout the day. This technology could help clinicians better manage patients who have glaucoma, the second leading cause of blindness in the United States.
Building on a capacitive pressure sensor previously designed by Dr. Fleischman and his team, they now seek to imbed a similar sensor (called the Tonochip IOP sensor) in an integrated contact lens, dubbed the iLens, to do just that.
Reducing IOP—fluid pressure within the eye—is the most effective way to manage glaucoma. Paramount to safely draining the collected fluid that leads to increased IOP is the ability to first accurately assess pressure levels.
Currently, IOP is measured through a test called applanation tonometry (AT), in which pressure is applied to the cornea. AT has several limitations, however. For one, its measures may be affected by the thickness of the cornea and the stiffness and curvature of the eye. Perhaps more importantly, while IOP changes continuously throughout the day, AT takes only one measurement at a single point in the day, thus missing potentially dangerous fluctuations in IOP.
The iLens, Dr. Fleischman explains, would offer solutions to many of these limitations.
“As we see it, the iLens will be an extended wear contact lens that is comfortable—easily conforming to the shape of the eye—aesthetically pleasing and easy to monitor,” he says. While the patient wears the contact lens, an external antenna reader that is connected to the sensor in the lens will continuously measure pressure, able to monitor and detect potential changes in IOP at all times the lens is being worn.
Dr. Fleischman’s vision for the iLens and its potential uses and benefits does not end here, though. “Our ultimate hope is that the iLens be used not just to detect disease-signaling IOP changes, but also to enable smart delivery of glaucoma medications.”
While glaucoma can be treated with eye drops, they can be difficult to administer and, as a result, usually only a small percentage of the solution is absorbed into the eye. Dr. Fleischman says the Tonochip would be a necessary element to create a smart contact that could dispense medication directly in response to real-time IOP.
“Using an iLens to measure IOP regularly can detect fluctuations and enable treatment, by either delivering a personalized eye drop regimen through the lens or enabling clinicians to treat fluctuations as they arise,” notes Dr. Fleischman. “It would also allow patients to observe their own IOP more regularly, which could encourage better compliance with eye drop regimens.”
The iLens integrated contact lens is one example of the research carried out in Dr. Fleischman’s lab, which concentrates on the use of micro- and nano-technology in biomedical applications. This involves shrinking high-functioning large systems into small computer-like chips for implantation or minimally invasive procedures, which enables new capabilities and technologies for unmet medical needs.