| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4034111 | Vision Research | 2011 | 13 Pages |
The first physiological process influencing visual perception is the optics of the eye. The retinal image is affected by diffraction at the pupil and several kinds of optical imperfections. A model of the eye (Thibos & Bradley, 1999), which takes account of pupil aperture, chromatic aberration and wavefront aberrations, was used to determine wavelength-dependent point-spread functions, which can be convolved with any stimulus specified by its spectral distribution of light at each point. The resulting retinal spectral distribution of light was used to determine the spatial distribution of stimulation for each cone type (S, M and L). In addition, individual differences in retinal-image quality were assessed using a statistical model (Thibos, Bradley, & Hong, 2002) for population values of Zernike coefficients, which characterize imperfections of the eye’s optics. The median and relatively extreme (5th and 95th percentile) modulation transfer functions (MTFs) for the S, M and L cones were determined for equal-energy-spectrum (EES) ‘white’ light. The typical MTF for S cones was more similar to the MTF for L and M cones after taking wavefront aberrations into account but even with aberrations the S-cone MTF typically was below the M- or L-cone MTF by a factor of at least 10 (one log unit). More generally, the model presented here provides a technique for estimating retinal image quality for the S, M and L cones for any stimulus presented to the eye. The model is applied to some informative examples.
► A model of pupil aperture, chromatic aberration and wavefront aberrations was used to determine retinal images. ► Included individual differences in the eye’s optics, using the distribution of Zernike coefficients in normal population. ► Determined normal-population median as well as extreme (5th/95th percentile) MTFs for S, M and L cones for EES ‘white’ light. ► Even with wave aberrations, typical S-cone MTF is well below the M- or L-cone MTF by a factor of at least 10 (one log unit). ► The model is applied also to chromatic stimuli in several informative cases.
