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Quantifying adaptation and fatigue effects in frequency doubling perimetry.
Andrew John Anderson1, Allison Maree McKendrick
1Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia. aaj@unimelb.edu.au
Investigative Ophthalmology & Visual Science
|January 26, 2007
Summary
The "second-eye effect" in perimetry, where the second eye tested shows reduced sensitivity, diminishes over time. This adaptation, not fatigue, highlights the importance of steady binocular adaptation for accurate visual field testing.
Area of Science:
- Ophthalmology
- Visual Neuroscience
Background:
- Frequency doubling perimetry (FDP) is a common visual field test.
- A known phenomenon is the
- second-eye effect,
- where thresholds are typically higher (indicating reduced sensitivity) when testing the second eye compared to the first.
Purpose of the Study:
- To investigate the temporal evolution of the
- second-eye effect,
- in frequency doubling perimetry.
- To examine systematic changes in visual thresholds within the first eye during perimetric testing.
Main Methods:
- Four subjects underwent FDP testing using 0.5-cyc/deg gratings at 18 Hz, with thresholds tracked at 10-second intervals using a
- method of a thousand staircases.
- ], [
- Subjects performed sequential monocular testing after initial binocular adaptation.
- Baseline monocular thresholds and tests with translucent patching were also conducted for comparison.
Main Results:
- The
- second-eye effect,
- initially raised thresholds by 6 dB, decreasing to 4 dB by the end of the test.
- A
- first-eye effect,
- was observed, with thresholds increasing by approximately 2 dB during the first eye's test session.
Conclusions:
- Steady binocular adaptation is crucial for achieving reliable and stable perimetric thresholds.
- The observed effects are attributed to adaptation processes rather than visual fatigue, emphasizing the need for appropriate testing protocols to avoid misinterpretation.
