Optimizing diagnostic technologies to address glaucoma progression in clinical practice

November 8, 2008

The consequences of uncontrolled glaucoma progression can be severe. Technology companies have risen to the challenge with sophisticated diagnostic devices, but it falls to the average clinician to make the best use of these tools in monitoring patients' disease status over the years.

The consequences of uncontrolled glaucoma progression can be severe. Technology companies have risen to the challenge with sophisticated diagnostic devices, but it falls to the average clinician to make the best use of these tools in monitoring patients' disease status over the years.

Imaging devices have a number of potential applications in the glaucoma practice, according to David S. Greenfield, MD, professor of ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine. These devices can be used for documentation, measuring optic disc size, staging, risk assessment, glaucoma diagnosis, and monitoring of progression.

For the most part, the instruments live up to their potential and are ready for routine use in the clinical practice for all of these tasks except monitoring progression, said Dr. Greenfield at a continuing medical education symposium held during the American Academy of Ophthalmology annual meeting. The dinner symposium was held Saturday evening at The Foundry at Puritan Mill in Atlanta.

He rated the capability of the devices as a "maybe" rather than a solid "yes." He described the relative merits of confocal scanning laser ophthalmoscopy (Heidelberg Retinal Tomograph, Heidelberg Engineering), a scanning laser polarimetry device (GDx VCC, Carl Zeiss Meditec), and optical coherence tomography.

Another speaker, Robert Weinreb, MD, discussed using functional testing to complement structural testing. He noted that the rate of progression can be estimated by assessing risk. Given that the rate of progression is highly variable among patients with glaucoma, individualizing the perimetric rate of progression is beneficial in monitoring patients, planning treatment strategy, and identifying patients at risk of developing significant field loss that could affect their daily activity. Dr. Weinreb is Distinguished Professor of Ophthalmology and director of the Hamilton Glaucoma Center, University of California San Diego. He also served as program chairman for the evening.

A software package (Glaucoma Progression Analysis) for visual-field examinations (Humphrey Field Analyzer, Carl Zeiss Meditec) is one tool for predicting progression. It compares current and previous perimetry results and uses a set of symbols to plot the likelihood of progression, Dr. Weinreb said. The results can be summarized on a single page. The package now includes a metric for visual field loss; the calculation process for the visual field index reduces the contribution of cataract to vision loss.

Optic disc examination and imaging also are valuable in patient management and detection of progression, particularly for assessment of the optic nerve and the retinal nerve fiber layer, said Christopher Girkin, MD, MSPH. Dr. Girkin is professor of ophthalmology at the University of Alabama at Birmingham.

According to Dr. Girkin, evidence-based medicine supports the use of imaging to assess the risk of developing glaucoma. Prediction studies have been produced and more are in progress. There is little validation of imaging methods to define glaucomatous progression, although longitudinal studies are under way. He predicted the emergence of new technologies that will require further longitudinal validation.

Neeru Gupta, MD, PhD, discussed functional assessment and optic nerve imaging and what they reveal about retinal ganglion cells. Dr. Gupta is professor of ophthalmology and vision sciences and director of the glaucoma unit at Keenan Research Centre, Li Ka Shing Knowledge Institute, St. Michael's Hospital, University of Toronto, Ontario.

This continuing medical education activity was jointly sponsored by the New York Eye and Ear Infirmary and cme², in partnership with Ophthalmology Times, and was supported through an unrestricted educational grant from Pfizer Ophthalmics.

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