Octopus introduces the most advanced progression
Combining structural with functional findings is a key to judge the onset and progress in Glaucoma. Over the past 4 years, Haag-Streit developed the PolarGraph to facilitate structure function correlation and improve Glaucoma diagnostics and follow up. This new function has now been released in the Windows software package EyeSuite Perimetry Advanced, together with additional significant improvements for visual field evaluation.
Glaucomatous changes are characteristic in a way that they are affecting nerve fiber bundles that lead the visual information from the receptors to the optic nerve and further to the visual cortex. Often the functional changes caused by affected nerve fiber bundles show up in different locations of the visual field over time. However, these locations usually are along the same affected nerve fibers. Thus, bundling of the information of test locations along the same nerve fibers leads to a more stable base to identify regional changes and calculate the progression rate. Haag-Streit applied a map, describing the relation between visual field locations and the nerve fiber location at the optic disc to improve visual field diagnostics.
This nerve fiber map, based on findings of Hogan et al, is used in two ways: In the PolarGraph it defines, which angle of the optic disc corresponds with which test locations. The PolarGraph then shows the functionally affected nerve fibers and helps to validate functional findings with structural abnormalities and vice versa.
The ClusterTrend uses the map to group test locations with same or nearby nerve fiber bundles. These groups then yield more stable results than the usual point wise evaluation of test locations while preserving regional information.
A final step was to mathematically identify and signal relevant changes. The research group around Hans Bebie, PhD and Ernst Buerki, MD, addressed this issue by developing a novel method, the population based statistics . This mathematical model allows to identify truly progressing visual fields and visual field areas with more certainty than traditionally applied statistics and increases the doctors safety in judging functional changes.
Because Glaucoma management asks for it
The latest revision in the glaucoma management guidelines makes clear, how important it is to calculate the visual field change to make good therapeutic decisions. Practical recommendations therefore have recently been published . The Haag-Streit EyeSuite Software calculates this rate and allows to correspond with the guidelines. Beyond that, the EyeSuite ClusterTrend and PolarGraph show, which nerve fiber bundles and what areas in the visual field are most affected by the visual field change. This is especially important in two ways:
- Fast regional changes may require a more aggressive therapy but would go underestimated if just looking at (average) global changes.
- Early or subtle functional changes may be misinterpreted as „measurement noise“ unless confirmed with structural findings and vice versa. Exactly this confirmation now is facilitated with the new functions.
Availability
The new functions are available now in the Haag-Streit EyeSuite Perimetry Advanced release version 2.02. EyeSuite Perimetry runs on Windows PCs, is networkable and interfaces to EMR (Electronic Medical Record) systems. It imports and analyzes data of Octopus and HFA perimeters.