Thresholds for sampled sloan letters are smaller than sample spacing.

Purpose: Although the effect of spatial sampling on the visibility of grating stimuli is well described and well understood, little research has been conducted into the effects of spatial sampling on the visibility of letter optotypes. The purpose of this study was to investigate whether thresholds for spatially sampled Sloan letters were equal to or significantly smaller than the spacing between spatial samples.

Methods: For four visually normal subjects, we measured Sloan letter acuity thresholds, presented on a computer monitor, after the letters had been sampled by sampling arrays with 6.