Purchase this article with an account.
F.A. Ennis, C.A. Johnson; The Contrast Level for Equality of Detection and Resolution Acuity Thresholds Is Not Constant in Peripheral Vision . Invest. Ophthalmol. Vis. Sci. 2003;44(13):74.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: High-pass resolution perimetry (HRP) uses a fixed stimulus-contrast level for determining detection thresholds that are interpreted as sampling-limited resolution thresholds, suggesting that they provide a measure of retinal ganglion cell density. This is based on the assumption that, at the contrast level used, detection and resolution thresholds are equivalent for this procedure. If this assumption is correct, then contrast detection thresholds for stimuli at the resolution limit should be equal across retinal locations and subjects. Methods: We measured resolution acuity thresholds for grating stimuli at two retinal eccentricities in three subjects. For each of these six combinations, contrast detection thresholds were then measured for a grating of fixed spatial frequency, equal to the corresponding resolution threshold, and for a high-pass ring of fixed size, scaled to the corresponding resolution threshold. Results: The contrast thresholds thus recorded varied significantly between retinal locations and between subjects. Conclusions: Our findings indicate that a fixed contrast level does not produce results that correspond to sampling-limited resolution thresholds, and the assumption that detection and resolution thresholds are equivalent at any fixed contrast level for all retinal locations is not valid. We conclude that HRP thresholds cannot be interpreted as sampling-limited resolution thresholds, and this is not overcome by adjusting the fixed contrast level.
This PDF is available to Subscribers Only