
A pressure monitoring system, placed in the eye with an artificial lens during cataract surgery, could provide “a wealth of useful data” to help ophthamologists manage patients with glaucoma, according to Sydney’s Professor Ivan Goldberg.
University of Washington (UW) engineers have designed the low-power sensor that could be placed permanently in a person’s eye, enabling them to track hard-to-measure changes in eye pressure. The sensor would detect pressure changes instantaneously, then transmit the data wirelessly using radio frequency waves.
Eye pressure is believed to behave similarly to a person’s blood pressure, changing perhaps minute by minute. If the pressure in the eye is too high for the optic nerve to function, however, damage to the eye can begin, often with no pain or warning signs. This increased intraocular pressure is the main factor in glaucoma, which causes vision loss and ultimately blindness.
“Oftentimes damage to vision is noticed late in the game, and we can’t treat patients effectively by the time they are diagnosed with glaucoma,” said Tueng Shen, a collaborator and UW Professor of Ophthalmology. “Or,
if medications are given, there’s no consistent way to check their effectiveness.” As a result, many patients with the disease aren’t diagnosed early enough or aren’t on an accurate treatment plan, she added.
Professor Goldberg said this technology, along with other technologies being explored are welcome. “Intraocular pressure (IOP) is a major risk factor for both onset and progression of glaucomatous damage. IOP levels have been investigated for years for diagnosis and management, with ongoing interest in IOP peaks and also fluctuations.
“While IOP is a continuous variable, clinically we sample it and from very limited data, try to understand what treatment might be necessary for the vision of a particular patient to be made safe,” he said.
“Continuous measurements of IOP offer the promise of providing a wealth of useful data. By attempting to provide such information, this technology and the others that are being explored are most welcome.”
Professor Goldberg said the challenges are to ensure accuracy, reliability and validity. “These all have to be proven and it is changes in IOP mostly that are measured. Advances are awaited eagerly,” he added.
Prototype development underway
The researchers published their results in the Journal of Micromechanics and Microengineering and filed patents on an initial prototype of the pressure-monitoring device.
“No one has ever put electronics inside the lens of the eye, so this is a little more radical,” said Karl Böhringer, a UW professor of electrical engineering. “We have shown this is possible in principle. If you can fit this sensor device into an intraocular lens implant during cataract surgery, it won’t require any further surgery for patients.”
The research team wanted to find an easy way to measure eye pressure for management of glaucoma without the need to visit the ophthalmologist. They have proposed that the device could save patients from a second surgery and essentially make their replacement lens “smarter” and more functional.
The prototype uses radio frequency for wireless power and data transfer. A thin, circular antenna spans the perimeter of the device – roughly tracing a person’s iris – and harnesses enough energy from the surrounding field to power a small pressure sensor chip. The chip communicates any shifts in frequency that signify a change in pressure, with a close-by receiver. Actual pressure is then calculated and those changes are tracked and recorded in real-time.
Both cataracts and glaucoma affect a similar aging population so it seems a natural pairing to place a pressure monitoring device in a new lens during cataract surgery, the researchers said.
The team is working on downscaling the prototype to be tested in an actual artificial lens. Designing a final product that’s affordable for patients is the ultimate goal, researchers said.