New software is being bannered by Carl Zeiss Meditec (Dublin California) as providing physicians with far greater insight concerning how to diagnose for glaucoma and track the natural progression of the disease.
Traditional tests and software face a wide array of problems when used in detecting the progression of glaucoma, according to the company. These problems can include a patient’s eyes being severely dry on testing day, but not on another; a cataract forming between the time of the first and second test; or the inability to successfully sample the same location of the eye for each test.
These factors can produce results that vary greatly from one visit to the next because of these values and can detract from the true picture of the eye and the presence of glaucoma.
Carl Zeiss Meditec, a developer of glaucoma care products and a subsidiary of Carl Zeiss Meditec AG (Jena, Germany), has developed a solution that it says can overcome these variables that skew results. It has released its Humphrey Field Analyzer II-I (HFA II-i) with a new software upgrade, Guided Progression Analysis (GPA).
GPA is currently being shipped in the U.S., with a launch date in April internationally
“The new component to the device is the software,” Tom Fitzmorris, group product director for glaucoma of Carl Zeiss Meditec, told Medical Device Daily. “But the HFA has been available for several years now.”
HFAs — devices that measure vision and perception found in most eye doctor’s offices, but usually characterized as “clunky” — were introduced in 1984.
With the addition of GPA software to this nearly 25-year-old technology, the HFA II-i’s standard printout presents each glaucoma patient’s baseline fields (the measurement of a person’s visual field) and the disease staging vs. time, rate of progression and most recent test result — all on a single page — significantly reducing past test printouts.
GPA incorporates a statistical approach that takes into account measurement variability, scan quality and the patient’s age; progression analysis of average in retinal nerve fiber layer (RFNL); and slope of change.
Glaucoma is a degenerative disease of the optic nerve. Most types of glaucoma progress without obvious symptoms, which is why glaucoma is often described as the “sneak thief of sight.” Visual damage is largely irreversible and may lead to blindness.
Fitzmorris said that a common misconception is that the measurement for high eye pressure is the sole and definitive sign of glaucoma. Rather, he said that the “high pressure” reading acquired is merely an “indicator” of being at risk for the disease.
‘I think what we have to take into account is that we’re a device maker and we’re not practicing medicine here,” Fitzmorris said. “But what we hope we’re doing [with GPA] is providing a clearer picture on a patient’s visual field to give doctors a better chance at making a more accurate diagnosis.”
The software also gives a reading of the visual field index — a measure of the individual’s entire scope of vision — which can be interpreted and used with the software to project three to five years out of where a patient will be visually. The visual field index is measured in percentages. “For instance if a person is at 80% [for their visual field] at the age of 25 and in three years will be at 70%, then that is a pretty significant drop,” Fitzmorris said.
According to the company, a measure of 0% on the visual field index means perimetric blindness. The visual field index is plotted against age and extrapolates a rate of change of up to five years as opposed to any events during the exam. Results are presented through a linear graft that plots percentage lost over the years with expected rate in the next few years.
“The goal of our investment in new glaucoma technologies is to preserve eyesight for the nearly 60 million people worldwide suffering from this disease,” said Jim Taylor, Carl Zeiss Meditec president/CEO. “The HFA II-i with new GPA software helps doctors closely monitor their glaucoma patients and ensure that each patient is receiving the best course of treatment to prevent vision loss. We are proud that our Humphrey Field Analyzers have been a standard of care for nearly a quarter of a century and we are committed to continuing our efforts to provide new capabilities through new products and upgrade opportunities.”
The HFA II-i’s GPA program is based upon data gathered from a 15-center international clinical trial and its progression event analysis was used as an endpoint in the Early Manifest Glaucoma Trial.
The GPA software also is available for the GDx Scanning Laser Polarimeter and the Stratus OCT with Advanced Serial Analysis.
A 2006 study in the British Journal of Ophthalmology estimates that 60.5 million people will be affected worldwide by 2010, increasing to 79.6 million by 2020 as the population ages.