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Rarebit test principles use stimuli of minimal subtense (ideally smaller than receptive fields),

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

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Rarebit test principles use stimuli of minimal subtense (ideally smaller than receptive fields),

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

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

  3. 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.

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

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

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

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