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Margarita G. Todorova, Anja M. Palmowski-Wolfe, Hans Bebie, Josef Flammer, Matthias Monhart; A Comparison Between The Pulsed Ramp And The Normal Staircase Strategy Using The G Test Pattern. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5519.
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Due to the temporal summation, the defect depth of a continuous RAMP presentation is different from a regular short stimulus pulse (100ms or 200ms stimuli). The pulsed RAMP overcomes this problem by dividing the ramp into discrete stimuli of increasing luminosity with an inter stimulus time of 600ms (Palmowski-Wolfe et al). This study was performed in an attempt to test whether the pulsed RAMP strategy, which allows for shorter test duration, overcomes the reduced local resolution of the TOP strategy for application in all pathologies.
A G pattern test using the pulsed RAMP and a normal staircase strategy (NS) were performed using the Octopus 300 perimeter (Haag-Streit AG, Köniz). A total of 33 right eyes were statistically analyzed: controls (n=7); glaucoma patients (n=24) and patients with other than glaucoma pathology (n=2). Depending on the mean defect (MD) of prior visual field tests, the glaucoma group was subdivided into: group 1(MD<2.5dB, N=5), group 2(MD 2.5-6.0 dB; N=6), group 3(MD 6.0-12.0 dB; N=7), and group 4 (MD>12.0 dB; N=6). The mean defect (MD), the square root of loss variance (sLV, corresponding to PSD), the test duration and the pointwise accuracy related to calculated reference fields were evaluated (ANOVA; mixed-factors analysis of variance). These reference visual fields were averaged from pre and post study visual fields data.
The mean examination duration was 8.34min. (SD 2.02) for the RAMP, compared to 13.37min. (SD 2.67) for the NS. MD of the pulsed PAMP correlated well with the NS (r=0.89, Spearman's rank). Only within the glaucoma group with the most severe cases, the correlation was virtually inexistent (p=0.0184). The sLV of the pulsed RAMP correlated well but was on average 1.49 dB higher than of the NS. The absolute mean local deviations evaluated with the pulsed RAMP (r=0.381) deviated more than the NS local deviations when compared with the reference data
The pulsed RAMP stimulus allows for a shorter test duration than the normal strategy but not reaching the average test durations of a SITA, TOP or Dynamic strategy. The RAMP strategy produces an MD that is comparable to the normal strategy and is therefore suitable for the use in follow up. The gain in time however, goes along with reduced local accuracy and the pulsed ramp thus shows no advantage over other already accepted test strategies. Therefore, we recommend to prefer established fast strategies over the pulsed ramp strategy.
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