One of the only treatments for glaucoma currently is lowering internal eye pressure. But a miniature eye implant developed at Stanford could combine with a smartphone to advance the way doctors measure and lower a patient’s eye pressure.
Weekly visits to eye specialists for monitoring and control of increasing pressure within the eye are a way of life for millions who battle glaucoma, and hope to stave off blindness.
The tiny new eye implant could allow patients to take more frequent readings from the comfort of home. Daily or hourly measurements of eye pressure could help doctors tailor more effective treatment plans.
Internal Optic Pressure
Internal optic pressure (IOP) is the main risk factor associated with glaucoma. A continuous loss of specific retina cells and degradation of the optic nerve fiber is the result.
The precise mechanism linking IOP and the damage remains unknown, but in most patients IOP levels are correlated with the rate of damage.
Similar to blood pressure, internal optic pressure can vary day-to-day and even hour-to-hour. Other medications, body posture, or even a necktie that being knotted too tightly can affect it.
If patients are tested on a low IOP day, the test can give a false impression of the level of the disease and affect their treatment in a way that can eventually lead to worsening vision.
Critical Data Flow
The new implant was developed by Stephen Quake, Stanford University professor of bioengineering and applied physics, in collaboration with ophthalmologist Yossi Mandel of Bar-Ilan University in Israel.
The device is made up of a small tube. One end is open to the fluids that fill the eye; the other end is capped with a small bulb filled with gas.
As the IOP increases, intraocular fluid is pushed into the tube; the gas pushes back against this flow. When IOP fluctuates, the meniscus, the barrier between the fluid and the gas, moves back and forth in the tube.
Patients would be able to use a custom smartphone app or a wearable technology, like Google Glass, to snap a photo of the instrument at any time. The photos would provide a critical wealth of data that could steer treatment.
For example, in a previous study, researchers found that 24-hour IOP monitoring resulted in a change in treatment in up to 80 percent of patients.
Simplicity is Key
Prior to testing in humans, however, the scientists say they need to re-engineer the device with materials that will increase the life of the device inside the human eye. Because of the implant’s simple design, they expect this will be relatively feasible.
“I believe that only a few years are needed before clinical trials can be conducted,” said Mandel.
Surprisingly, the implant does not distort vision. When subjected to the vision test used by the U.S. Air Force, the device caused nearly no optical distortion, according to the researchers.
“For me, the charm of this is the simplicity of the device,” Quake said. “Glaucoma is a substantial issue in human health. It’s critical to catch things before they go off the rails, because once you go off, you can go blind. If patients could monitor themselves frequently, you might see an improvement in treatments.”
The implant currently is designed to fit in a standard intraocular lens prosthetic, which many glaucoma patients often get when they have cataract surgery, but the scientists are looking at ways to implant it on its own.
An implantable microfluidic device for self-monitoring of intraocular pressure
Ismail E Araci, Baolong Su, Stephen R Quake & Yossi Mandel
Nature Medicine (2014) doi:10.1038/nm.3621
Top Photo by Abe Kleinfeld