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Shawn R. Lin, Isabella N. Lai, Sanjeev Dutta, Kuldev Singh, Robert T. Chang; Comparison of Fixation Target Stability for RareBit and Humphrey Visual Field Tests. Invest. Ophthalmol. Vis. Sci. 2012;53(14):198. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To compare fixation stability and fatigue when testing with the Humphrey Field Analyzer (HVF, static fixation target) versus RareBit perimetry (RBP, kinetic fixation target) using a video gaze tracker.
Fourteen healthy subjects were tested in one eye using an ASL Mobile Eye Tracker as they completed both HVF 10-2 and RBP Central Field tests. All video gaze data was recorded at a rate of 30 Hz. Fixation stability was calculated as the distance in degree minutes from the fixation target to the subject’s actual gaze. In order to determine fixation fatigue for each test, the amount of unfixated time (eyes closed or >20º from target) was measured for each subject. Subjects were also surveyed to find out which test they preferred.
The kinetic RBP test resulted, on average, in 18% better fixation stability relative to the HVF test (p=0.02). A total of 9 out of 14 study subjects demonstrated better fixation stability with the kinetic RBP target, 3 showed approximately equal fixation stability with both tests, and 2 had better fixation stability with the static HVF target.Subjects spent a significantly longer amount of time unfixated during the HVF test (10.0 seconds) relative to the RBP test (0.9 seconds) (p=0.002). Eighty six percent of study subjects reported a preference for the RBP field test.
The use of a RBP kinetic fixation target is associated with more consistent fixation stability and less fixation fatigue during visual field testing than the HVF static target. The reduced fatigue with RBP may, at least partially, account for the greater comfort reported with this test relative to the HVF test.
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