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It is estimated by means of electron microscopy that the optic nerve of the turtle Pseudemys scripta elegans contains 394,900 fibers of which approximately 80% are myelinated. The total fiber count agrees well with counts obtained from electron microscopic studies on other turtle species. There are, however, differences among these species in the percentage(More)
In order to test a model of peripheral vision, various contrast sensitivity functions (CSF's) and fundamental eccentricity constants (FEC's) [see J. Opt. Soc. Am. A 8, 1762 (1991)] were applied to real-world, wide-field (6.4 degrees-32 degrees eccentricity) images. The FEC is used to model the change in contrast sensitivity as a function of retinal(More)
A technique is described for producing variable-resolution images whose spatial detail decreases as a function of distance from their centers. These images can be matched in some sense to the normal spatial inhomogeneities of the human visual system, as well as to various abnormalities in spatial discrimination. A set of images was generated with a series(More)
Intraocular scatter of monochromatic light was assessed in three subjects (ages 21, 38, and 43) using the equivalent veil technique. For an annular stimulus of 3 deg inner and 8 deg outer diameter, the scattered illuminance at the center averaged 1.2% of the surround and was independent of wavelength from 420 to 650 nm. These results are inconsistent with(More)
Saccaadic response preferences and latencies were measured using dual targets presented at 5, 10 and 15 deg along the horizontal meridian in either one or both visual hemifields. In the unihemifield condition, subjects exhibited a strong preference (about 95%) in favor of the target presented closer to the original fixation point. Further, the presence of(More)
An integrated system is described which we have found useful for efficiently collecting and analyzing both static and dynamic accommodation data using the Canon Autoref R-1 refractometer. The system consists of hardware modifications and software designed to both facilitate the measurement of accommodation and to process the resulting data. Several features(More)
The directional sensitivity (DS) of the red (pi 5), green (pi 4), and blue (pi 1) color mechanisms was measured for both the horizontal and vertical pupil meridians, thus localizing the peak of each pi-mechanism DS function within the two-dimensional pupillary aperture. In the horizontal meridian, there were greater differences among observers in DS(More)