For earlier and more reliable diagnosis of glaucoma, engineers are developing a detection device that bridges advanced research and practical applications
Jan. 23, 2012
Three days a week, Dr. Grady Rylander treats patients at the Eye Institute of Austin, a private practice he joined 34 years ago after graduating from The University of Texas at Austin and finishing his residency at UT Health Science Center at San Antonio.
Of the 60 to 90 patients Rylander treats weekly, half are returning patients who have glaucoma, a group of eye diseases that irreversibly damage eyesight and affect 1 in 10 people over age 80 and 1 in 200 people under 50.
Known as the “silent thief of sight,” glaucoma is the second-leading cause of blindness worldwide, largely because the disease is often not detected until it is already advanced. Complicating the chances of early detection are the fact that some forms of glaucoma have no obvious symptoms and that current detection methods are limited in how quickly they can spot warning signs of the disease.
“Glaucoma is treatable if it’s detected,” said Rylander, who also serves as a professor in the Cockrell School of Engineering’s Biomedical Engineering Department. “But there’s no way to repair the damage caused by the disease prior to detection, so the earlier we can identify a patient with the disease the better off that patient will be.”
Working alongside a team of graduate students and his colleague in the Biomedical Engineering Department, Professor Thomas Milner, Rylander is helping develop technology to detect glaucoma much earlier than the current gold-standard-diagnostics used in clinics.
The researchers have created a device that builds on existing technology but is able to show and measure changes in the eye that can’t be seen through current detection methods.
The decade-long collaboration between the two professors combines Milner’s expertise in optics and engineering with Rylander’s insight into the medical field and understanding of what’s practical in a clinical setting.
Rylander, who considers himself an engineer first and physician second, joined the university in 1978 because, he said, he wanted to go where he could help make things better for people through research and teaching. While juggling work at his clinic, Rylander climbed the academic ranks to become a full professor and, eventually, to help found the Biomedical Engineering Department.
He served on the faculty committee that recruited Milner to the university in 1998. The two researchers immediately saw where their research interests could be combined. The glaucoma detection technology is the product of their collaboration.
Although results from two major studies are still being analyzed, preliminary findings on the device’s efficacy are promising. The researchers are hopeful the technology could revolutionize how glaucoma is detected and improve outcomes for patients who have the disease.
“Most people lose most of their sight before glaucoma can even be detected,” Milner said. “So there is a pressing need for this technology and for detecting these diseases earlier.”
Bridging advanced research with practical applications
For decades, the textbook explanation of glaucoma has been that it’s caused by a buildup of pressure in the eye. The buildup occurs when a clear fluid – meant for nourishing eye tissues by passing naturally in and out of a chamber in the front section of our eyes – doesn’t drain quickly enough. The pressure can damage the eye’s optic nerve, which transfers the images we see to our brain for processing.
Because of this, doctors have typically relied on eye and eye pressure exams to check for glaucoma. But these tests aren’t perfect. Pressure in the eye is rarely stable and changes sporadically based on variables such as stress, diet and even time of day (in the morning a person’s eye pressure is typically higher than in evenings). The fluctuation makes it difficult for doctors to reliably read a patient’s eye pressure – so much so that pressure exams don’t detect glaucoma in up to 20 percent of patients who have the disease, Rylander said.
“A pressure check alone is an unreliable and gross under-sampling if a patient only goes to the eye doctor once every three or four years,” Rylander said.
The most revolutionary and popular detection method is a technology known as OCT (optical coherence tomography). Created in the 1990s, the noninvasive technology harnesses light to produce high-resolution, cross-sectional images of the retina and is able to measure the thickness of nerve fiber layers in the eye. Among OCT’s applications, Milner is also using it to develop an imaging technique with the potential to predict, or even prevent, heart attacks.
Although OCT is a major improvement from previous methods used to detect eye diseases, the technology is still limited in how soon it can spot glaucoma. That’s where Milner and Rylander are applying their expertise.
Led by Milner, the researchers have developed a form of OCT, known as polarization sensitive OCT, that produces higher contrast images of the eye and shows in finer granularity whether nerve layers in the retina are decreasing in thickness. Such decreases indicate glaucoma.
The device can also measure how much light is reflected out of the eye – a measurement that, if low, is an indicator of glaucoma. A healthy eye bounces light out of the retina. When the amount of light being reflected drops, Rylander and Milner believe it’s a sign that mitochondria – organelles that act as power plants to cells by supplying them with chemical energy – are sick, damaged or dying because of glaucoma. The researchers relied on the informatics expertise of another colleague in their department, Professor Mia Markey, who helped analyze data and facilitated the importance of light reflectivity in their studies.
Preliminary results from a study on primates and a collaborative clinical study between Duke University and The University of Texas at Austin have indicated that the researchers are correct, though both professors say that more in-depth studies are needed to validate their initial findings.
Dr. Stuart McKinnon, a glaucoma specialist at Duke Eye Center in Durham, N.C., who was involved in clinical tests of the technology, said a problem with current detection methods is that they rely on detecting loss of peripheral vision to diagnose glaucoma.
“But up to 50 percent of the optic nerve fibers may be lost before we detect vision problems,” McKinnon said. “This new device is capable of detecting changes in the structure of these nerve fibers before they disappear, and this represents a major step forward in our understanding of the disease. If we can diagnose glaucoma earlier, we can begin treatment much sooner and prevent vision loss before the patient’s vision is affected.”
While there is a lot of enthusiasm about the technology, Rylander said scientists and physicians still want to see how much earlier glaucoma can be detected with the device.
“That’s a question we hope to answer soon with larger studies,” Rylander said.
The benefit of collaboration
For patients such as Phyllis Ward, the answer to that question makes all of the difference. Ward, 87, was diagnosed with the disease seven years ago during an eye examination at Rylander’s north Austin clinic.
She did not have symptoms of the disease, so without a diagnosis she could have continued living with glaucoma and not known it until her vision was severely damaged.
Since her diagnosis, Ward takes eye drops daily that treat her glaucoma and keep it from progressing. The drops help relieve pressure in the eye by allowing better fluid drainage.
“I’m vigilant about taking those eye drops,” Ward said. “Because eyesight is one of the most important parts of our bodies. I have to take care of it.”
Patients such as Ward make the research both personal and professional for Rylander. He and Milner recognize the benefit of combining their expertise and backgrounds to tackle early glaucoma detection.
“Engineers come up with technology and treatments but we don’t see how these devices are applied and administered by physicians to patients,” Milner said. “So it’s important for engineers to work with clinical physicians, or at least have good knowledge of what the constraints are that physicians and their patients face, be it time, cost or tolerability.”
Through Milner’s collaboration with Rylander, the researchers are able to see both sides of technology creation and technology application.
“A third of the students in our department are pre-med and they’re among the brightest students in the world. When I interact with them there’s always this question of, ‘Should I go into medicine and be a user of instrumentation, or should I be a producer of instrumentation?’” Rylander said. “I try to tell them that really you can do both.”
For more information, contact: Melissa Mixon.