title: Variation in ocular modulation and phase transfer functions with grating orientation.
abstract: For circular pupils of diameters < or = 2 mm the optical performance of the eye in monochromatic light is effectively diffraction-limited, so that its modulation transfer function (MTF) is essentially independent of grating orientation and its phase transfer function (PTF) is close to zero. For larger pupils, however, the wave aberration of the eye usually exceeds the Rayleigh quarter-wavelength limit. It is shown that the monochromatic MTF may then display marked variation with orientation and the associated PTFs can be non-zero. The exact effects vary markedly with the individual subject. In white light additional asymmetries may occur due to transverse chromatic aberration.
authors.affiliation: Department of Optometry and Vision Science, Glasgow College, UK.
authors.forename: G
authors.initials: G
authors.lastname: Walsh
authors.forename: W N
authors.initials: WN
authors.lastname: Charman
mesh_terms: D015350:Contrast Sensitivity / Q000502:physiology*; D006801:Humans; D007498:Iris / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology*; D012399:Rotation