While there has been tremendous developments in imaging technology over the last few years there has been relatively little development in visual field technology. In ophthalmology, threshold tests (SITA) and the 24-2 test pattern are almost universally used for the detection and management of glaucoma. SITA dates back to 1997 and the 24-2 test was present in the first Humphrey Visual Field Analyzer which came out in the 1980's. Recent research has highlighted the high variability in threshold estimates at damaged locations in the visual field and proposed that the current threshold test limit the range of intensities to where reliable estimates of thresholds can be obtained. Further research has shown that the 24-2 test pattern can miss small defects that fall within the central 10 degrees and that more stimuli should be placed in this functionally important region. Optometrist have always had a major role in the detection of glaucoma. They have tended to rely upon supra-threshold tests with a variety of different test patterns. The supra-threshold test increments are usually fixed and do not take into account the relationship between variability and eccentricity. Small modifications to supra-threshold tests could improve the compatibility of supra-threshold and threshold tests. Following a discussion of these issues the presentation will highlight recent developments designed to address these issues and improve the overall performance of visual field tests for the detection and management of glaucoma. Learning Objectives
- To make delegates aware of the high variability of threshold estimates at damaged location in the visual field of glaucomatous eyes.
- To highlight how small central defects within the central 10 degrees can easily be missed with widely used 24-2 test patterns. To review proposed changes to thresholds tests that address both the variability and sampling issues.
- To review the test increments used in supra-threshold perimetry and how these can be adapted to match the changes in variability with eccentricity.
- To review the test patterns used in supra-threshold perimetry and how these could be modified to improve compatibility with those used in ophthalmology.
David Henson, Emeritus Professor and Clinical Advisor, University of Manchester/Elektron Eye Technology