Participants in UC Davis' landmark glaucoma study celebrate study's completion and findings
Michael Gallagher was nearing the end of his career as a pilot with the U.S. Air Force when, during a routine physical, he learned he had elevated pressure inside his eyes and was at risk for glaucoma, a leading cause of blindness. Not long afterward, from a newspaper article, he learned something else — UC Davis was participating in a nationwide glaucoma study and was looking for people who had high eye pressures but normal vision.
"I just said, 'Wow! That has my name all over it,'" Gallagher recalled.
Gallagher and 116 other people in the Sacramento area eventually signed up, giving UC Davis the largest patient base of the 22 centers that participated in the Ocular Hypertension Treatment Study. Begun in 1994, the OHTS examined 1,636 people 40 to 80 years of age over an almost 15-year period. Now, after the publication of 30 research papers, the development of a validated prediction model for glaucoma and conclusive proof that daily use of pressure-lowering eye-drops can delay or prevent the disease, the $30 million to $40 million clinical trial is ending.
According to James D. Brandt, professor of ophthalmology and lead investigator of the glaucoma study at UC Davis, the OHTS has been one of the most quoted studies in the scientific literature — not just in the U.S. but worldwide. All the more reason, he said, that the study's close should be an opportunity to say thanks to those who made it possible — the patients who, twice yearly, underwent extensive eye exams and visual tests.
"They enabled us to answer some very fundamental questions regarding ocular hypertension and glaucoma," said Brandt, who during the course of the study discovered, among other things, that people with thinner corneas are at greater risk. "Without them volunteering their time, we wouldn't have been able to achieve all that we have achieved."
To mark the end of the study, the UC Davis Health System Eye Center (formerly the Department of Ophthalmology and Vision Science) hosted a reception for study participants.
Brandt gave an address on the significance of the study and its contribution to the understanding of glaucoma. Other speakers included Claire Pomeroy, vice chancellor of human health sciences and dean of the School of Medicine, and Ann Bonham, executive associate dean of Academic Affairs.
"It is only through the dedication of such committed patients that we are able to understand long-term diseases and develop new treatments for chronic conditions like glaucoma," said Michael Kass of Washington University in St. Louis, who served as principal investigator of the OHTS. He also praised Brandt for his "leadership" and for his investigations of the impact of cornear thicness on the diagnosis and management of glaucoma. "He was the person who suggested measuring corneal thickness. It was not part of the original protocol," Kass said.
Kass also mentioned that UC Davis played a key role in another sense — serving as a center for the reading and analysis of thousands of visual field tests for the study.
The OHTS first made news in 2002 when researchers revealed that pressure-lowering eye drops reduced by more than 50 percent the development of primary open-angle glaucoma, the most common form of the disease, in study participants. Until then, doctors did not know if treating elevated eye pressure before glaucoma developed could delay the onset of the disease.
Researchers also found evidence that personal risk factors, such as older age and African descent, as well as ocular risk factors, such as higher eye pressure, anatomy of the optic nerve, and thinness of the cornea, were associated with the development of glaucoma in study participants.
UC Davis Health System Eye Center
The ultimate goal of the UC Davis Health System is to find cures for blinding eye diseases and towards that end, clinical trials are essential. Conducting human subjects research gives us an opportunity to use the latest, most promising treatments in the form of drugs, devices, or procedures in an effort to cure or manage ocular diseases.
We also conduct a multitude of studies that do not involve drugs or devices, but may collect data through questionnaires, patching, blood and surgical specimens, and imaging.
Our clinical trials cover all subspecialties, including Glaucoma, Cornea, and Vitreo-Retinal Disease.Click here to learn more
The study was back in the news in 2004 with the finding that pressure-lowering eye drops can delay or prevent glaucoma in almost 50 percent of African-Americans who are at higher risk for developing the disease. Researchers said that 8.4 percent of African-American participants who received eye drops developed glaucoma. In comparison, 16.1 percent of the African-American participants who developed glaucoma did not receive the daily eye drops.
Since 2004 there have been other findings, such as that hemorrhages on the optic disc increases the risk of developing glaucoma and that corneal thickness affects the measurement of how patients respond to what is still the only available preventative treatment — pressure lowering eye drops.
Both Kass and Brandt said additional research discoveries would be made public beginning in November. Kass added that it may take another year, perhaps even another two years, before all the findings are published.
"Big studies like this go slowly," Kass said.
As for Gallagher, he's one of the lucky ones. Some fifteen years after doctors first noticed that he had elevated eye pressures, he's showing no signs of glaucoma. That might have something to do with the fact that the retired pilot, now 63, has unusually thick corneas, "the thickest we've ever seen," according to Ingrid Clark, coordinator of the OHTS for UC Davis.
Gallagher, a resident of Portland, Ore., attended the reception, that attracted at least 50 of the volunteer subjects. Rowena Hubbard, 73, of El Dorado Hills and Scotty Walton, 53, of Roseville, also attended. Neither Hubbard, who has a family history of glaucoma, nor Walton, who is African American, has developed the disease. Both, like Gallagher, are taking eye drops on a daily basis.
Whether any of them does get the disease can't be known for sure. What is clear is that the OHTS has been a long-term commitment for all concerned.
"I like to joke that we've all grown old together," Brandt said.
The Ocular Hypertension Treatment Study was funded by the National Eye Institute and the National Center on Minority Health and Health Disparities, two components of the federal government's National Institutes of Health.