Monitoring of pressure inside the eye is key to early detection of glaucoma, a group of conditions that damage the optic nerve, and a leading cause of blindness in the US where it affects around 2.2 million people, according to the Glaucoma Research Foundation. Now engineers at the University of Washington in Seattle are designing a sensor that can be fixed permanently inside the eye and continuously monitor hard-to-measure changes in eye pressure.
The team foresees a future - not too far away - where the human eye encapsulates its own high-tech information center, keeping a close watch on important health changes and issuing warnings of when it is time to see the eye doctor.
The prototype the engineers are working on would be implanted along with an artificial lens when a patient has cataract surgery. Once in place, the sensor detects pressure changes in the eye immediately, and transmits the data wirelessly using radio frequency waves.
Eye pressure fluctuates over the day, much in the same way as blood pressure. If the pressure inside the eye gets too high it can begin to damage the optic nerve - often with no pain or warning sign. Increased intra-ocular pressure is the main factor in glaucoma.
The team foresees a future where the human eye encapsulates its own high-tech information center, keeping a close watch on important health changes.
The engineers describe their new device - which incorporates a pressure sensor and radio chip, and an antenna that circles the perimeter of the artificial lens - in a paper published in the Journal of Micromechanics and Microengineering. Patents on the initial prototype design have already been filed.
The device itself just has to handle raw data. The heavy computational work can then be done in another device that receives the data - such as a handheld device or possibly even built into a smartphone, says the team.
Senior author Karl Böhringer, a professor of electrical engineering and bioengineering, says no one has ever embedded electronics inside the lens of the eye before, and their prototype shows it is possible in principle. The added benefit, he explains is:
"If you can fit this sensor device into an intraocular lens implant during cataract surgery, it won't require any further surgery for patients."
Cataracts and glaucoma affect a similar aging population so it makes sense to pair the procedures, says the team.
Glaucoma damage is often spotted too late
When they started their work the researchers were looking for an easy way to measure eye pressure. At present there are two ways to do this, and both require a visit the ophthalmologist. This means patients at risk for glaucoma get to have their eye pressure measured a few times a year, at the most.
But if the ophthalmologist could insert a pressure monitor directly into the eye, then pressure would be tracked continuously. This could be done during cataract surgery - a procedure undergone by some 3 to 4 million Americans every year to correct blurred vision or glare caused by a hazy lens.
Co-developer Tueng Shen, a professor of ophthalmology, says they are working on making the device simple and reliable, and well-suited for clinical use, and adds:
"We want every surgeon who does cataract surgeries to be able to use this."
She says often the damage to eyesight is noticed too late for treatments to be effective. Also, if medications are given, there is no effective way to monitor the results. She adds that there is a need for techniques to diagnose glaucoma earlier and ensure patients are on the correct treatment plan.
The current prototype is too big to fit in a lens, but the team is confident it can downscale the technology. The engineers have already tested that it works when embedded in the same flexible silicon that artificial lenses are made of.
The Coulter Foundation and the University of Washington funded the research.
In February 2014, Medical News Today reported how researchers from the University of California, Los Angeles have developed a nanodiamond-embedded contact lens that delivers glaucoma drugs more effectively to improve the treatment of the condition.
Written by Catharine Paddock PhD