Refinement of Glaucoma Testing, Treatment Expected from US, UK Study

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An Indiana University School of Optometry researcher’s ongoing work to improve testing for and treatment of one of the world’s leading causes of blindness will advance with support from a $2.35 million grant from the National Institutes of Health.

IU School of Optometry Professor William H. Swanson will lead a research group that will conduct patient studies at optometry clinics in Bloomington, Indianapolis and New York City. Coupled with data from the United Kingdom, Swanson’s team will work to improve methods for screening and testing for the presence, progression and pattern of damage due to glaucoma, a disease the National Eye Institute says affects 70 million people worldwide.

Swanson came to IU in 2006 from State University of New York State College of Optometry, where he remains an adjunct research professor. He holds a Ph.D. in biophysics and theoretical biology from the University of Chicago.

"Dr. Swanson’s recruitment was made possible by the 2003 Commitment to Excellence (CTE) award to the School of Optometry,” said Sarita Soni, Interim Dean of the School of Optometry.

The goals of the CTE proposal were to strengthen patient-based disease research at the School of Optometry, the school’s Borish Center for Ophthalmic Research (BCOR) and IU Bloomington, and to better position the School of Optometry and the BCOR to compete for NIH-funded, patient-based research in ocular diseases and treatments.

“Dr. Swanson is precisely the type of faculty member we had in mind when the CTE proposal was developed,” Soni added. “And I am grateful that IU Bloomington saw it fit to invest in the School of Optometry.”

Swanson’s research has already led to reconsideration of the widely held view that peripheral vision defects do not occur until after extensive loss of the ganglion cells. Ganglion cells transmit visual information from the retina to the brain.

Corroborated both independently and collaboratively by researchers in London, England, Swanson found widespread misinterpretation in comparisons of glaucoma patient data based on “inappropriate statistical analyses” that did not account for differences in units of measurement, lack of an independent variable and differences in dynamic range.

“This issue has now been raised by a number of laboratories and there is increasing awareness of the need to compensate for differences in linear versus logarithmic units,” Swanson said of incorrect conclusions based on comparing structural (linear) and functional (logarithmic) measures in glaucoma patients.

Swanson’s research path will now move toward optimizing and reducing variability in the perimetry testing that is used to find certain patterns of vision loss, especially early changes in vision caused by nerve damage from glaucoma. Regular perimetry tests are also used to monitor whether or not treatment for glaucoma is preventing further vision loss.

Perimetry, or visual field testing, measures central and peripheral vision, as a subject sits and looks inside a bowl-shaped instrument called a perimeter. The subject pushes a button each time a flash is seen while a computer notes the site of each flash and whether or not the subject pressed the button when the respective flash occurred. A resulting printout then displays areas of vision loss.

With a new quantitative model for creating statistical methods that accurately compare different clinical measures, along with development of a next generation of perimetry for glaucoma patients called contrast sensitivity perimetry (CSP), Swanson’s work can focus on optimizing protocols for CSP testing in clinics, on testing the new model’s predictions in a large database and on developing a better understanding of the relations between how glaucoma damage is measured by CSP and other clinical methods.

One hope researchers have is that close analysis of the data from a United Kingdom study group—450 glaucoma patients, some of whom have gone untreated—could reduce both health care costs and side effects to patients associated with overtreatment. Data will also be gathered from 100 additional patients tested at optometry clinics in Bloomington, Indianapolis and New York City.

“This research will produce a deeper scientific understanding of perimetry and will lead to improved methods for using perimetry in clinical studies, treatment trials and care of individual patients,” Swanson said. “The potential public health benefit is substantial, given the large number of patients with glaucoma.”

Working with Swanson at Indiana University will be Dr. Victor Malinovsky, a clinical professor at the IU School of Optometry’s Community Eye Care Center in Bloomington, Dr. Bradley Sutton, a clinical associate professor at the IU Indianapolis Eye Care Center, and Dr. Julie Torbit, a clinical assistant professor also at the IU Indianapolis Eye Care Center.

Collaborating with IU will be Dr. David Crabb at the Applied Vision Research Centre in the Department of Optometry and Visual Science at City University London, Dr. Mitchell Dul, director of the Glaucoma Institute at the SUNY State College of Optometry, and Drs. David Garway-Heath and Rizwan Malik, both of the Glaucoma Research Unit of Moorfields Eye Hospital in London.

Source:  Indiana University

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