Piervincenzo Rizzo is developing a new glaucoma test with an NIH grant

Glaucoma is a disease of the optic nerve often characterized by high pressure in the eye caused by a buildup of fluid. One way to screen for and monitor the disease is to measure that intraocular pressure using a tonometer, a device that shoots a puff of air or probe to measure pressure on the eye's surface.

The levels of fluid in the eyes naturally wax and wane throughout the day, however, so a single test doesn't show the whole picture.

"When you go to a doctor, they take one-point measurement," said Piervincenzo Rizzo, professor of civil and environmental engineering in the Swanson School of Engineering. "But really, you don't know if you are in a peak or in a valley" as far as your average eye pressure goes.

Drawing on his experience in nondestructive evaluation and structural health monitoring - engineering disciplines focused on testing and evaluating structures without affecting their performance or integrity - Rizzo decided he could build a better tool. The National Eye Institute, part of the National Institutes of Health, has awarded him and his team a $403,633 grant to develop one.

The improved tool will be portable, inexpensive and easy for patients to use several times throughout the day without a trained specialist on hand.

Imagine throwing a tennis ball at a wall. "The way the ball bounces back can tell you something about the wall," Rizzo said. If the wall is rigid and hard, for example, you'd expect the ball to bounce back faster than if it were thrown at a soft and squishy wall.

Rizzo's device works similarly. It consists of a series of small metal spheres inside a tube. The top sphere is lifted, then dropped, sending a traveling wave through the spheres to the patient's closed eyelid, where it bounces back up to a sensor, which analyzes the waveform, determining the density of the patient's eye.

To go from tennis-ball-sized to eyeball-sized, Rizzo enlisted the help of Samuel Dickerson, professor of electrical and computer engineering in the Swanson School, to shrink the electronic components and write the algorithms that process the signals in the return wave.

"We did this four or five years ago in a huge macrostructure," Dickerson said. "We're eyeball sized now."

With a smaller device, the team has been able to test the new technology on a synthetic eyeball filled with water to simulate pressure. And it worked.

"Now the project is making this into an instrument that we can take to Ian Connors' lab and get some real data on human eyes in a real, finalized instrument," Dickerson said.

Connor is the division chief of the glaucoma and cataract service at UPMC Vision Institute and an associate professor of ophthalmology in Pitt's School of Medicine.

Sometimes, Connor said, he'd see patients with obvious progression of their glaucoma, but with seemingly normal intraocular pressure. Sometimes that led to a 12-hour day of hourly testing for the patient. "Then you bring them in, and you discover that in the middle of the day, they're spiking up to some much higher number," Connor said, "You never would have known that if you weren't measuring them throughout the day."

The benefit to his patients of a portable, easy-to-use device is clear.

"In the lab, the methodology seems to work," Rizzo said. "So now we will make this device portable and test it on people to see if we can see the signals, and then analyze them."