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A.M. Palmowski–Wolfe, M. Todorova, H. Bebie, M. Monhart; A Comparison Between a Pulsed Ramp Strategy and a G1 Test Pattern Using Normal Strategy . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4318.
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Purpose: New perimetric strategies aim at achieving a comparable sensitivity while taking considerably less time to perform than a standard e.g. normal bracketing strategy. One attempt in this direction was a continuous light increment ramp stimulus strategy. However, with longer stimulus duration temporal summation results in an increase in threshold up to a maximum level, thus producing less deep scotoma and/or generally higher thresholds. This problem may be overcome by using a pulsed rather than a continuous ramp stimulus. In this study, a new pulsed ramp stimulus is compared to a normal strategy. Methods: 15 subjects without, with early (MD 2–6), moderate (MD 6–12) or advanced (MD >12) visual field defects underwent visual field testing of their OD in random order with a pulsed ramp strategy and normal strategy using the G1 pattern on an Octopus 301 perimeter (Haag–Streit AG, Köniz). For the ramp stimulus, a sequence of standard stimuli of 100 ms duration was presented in the same location, starting below threshold and increasing in intensity. The reaction time was measured at different locations and used to calculate the true position of the response on the frequency–of seeing curve. The response threshold was used to calculate the starting point of stimulation at neighboring locations. Results however were not interpolated across test points. Mean defect and squared loss variance were compared. Results: The pulsed ramp stimulus allowed for a much faster examination time of, on average, 5:25 minutes versus 14:44 minutes for the normal strategy. Overall, there was a high correlation between the slope of the MD in the normal strategy versus the MD of the pulsed ramp strategy, suggesting a similar defect depth in both strategies. sLV values were slightly higher using the pulsed ramp stimulus in normal subjects. The percentage of false negative and false positive responses was similar for both methods. Conclusions: The pulsed ramp stimulus is a promising method for fast threshold testing while producing similar results to the normal strategy.
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