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Rarebit test principles - use stimuli of minimal subtense (ideally smaller than receptive fields), - at high & fixed contrast, - check once only for the.

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Presentation on theme: "Rarebit test principles - use stimuli of minimal subtense (ideally smaller than receptive fields), - at high & fixed contrast, - check once only for the."— Presentation transcript:

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2 Rarebit test principles - use stimuli of minimal subtense (ideally smaller than receptive fields), - at high & fixed contrast, - check once only for the presence of function (no thresholding), - in ever-new, non-overlapping locations; - calculate hit rate - briefly exposed (to negate sweep gains);

3 Model of receptive field matrix with 10% ”holes”.

4 Model of receptive field matrix with 10% ”holes”. A macro stimulus can activate several good fields. Micro stimuli (”rare bits”) in ever new positions should on average activate 9 fields out of 10.

5 Key rarebit parameters: Dot size: 0.5 x MAR* * Minimum Angle of Resolution Contrast: high & fixed

6 Main result parameter Hit Rate = Sum of responses Sum of presentations Expected normal hit rate  100% (except at blindspot and in angioscotoma)

7 Case of mild optic neuritis HRP (High-pass Resolution Perimetry) RBP (Rarebit Perimetry) VA = 0.8 = 20/25


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