Neural limits of visual resolution

Aims: The aim of this thesis was to formulate a model of retinal neural circuitry in humans based on morphological estimates of retinal cone and ganglion cell populations, to compare results based on this model to psychophysical measurements of visual resolution and identify the retinal neural factors that limit visual resolution. Materials & Methods: Total displacement of central ganglion cells from foveal cones was obtained by estimating the length of fibers of Henle in four human retinas along the nasal or vertical hemi-meridians. Quantitative estimates of ganglion cell and cone densities were made using a modified disector method in vertically sectioned human retinas and ganglion cell densities were adjusted for central displacement. High-pass Resolution Perimetry (HRP) thresholds were used as a psychophysical estimate of visual resolution throughout this work. Functional magnetic resonance imaging (fMRI) estimates of the human linear cortical magnification factor were obtained from the literature. Resolution and detection thresholds of computer generated high-pass filtered optotypes were recorded under equal lighting and luminance conditions