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Previous studies have shown that most patients with bilateral macular disease use a single retinal area during fixation which is typically located near the edge of the central scotoma. Through frame-by-frame playback of videorecordings showing the target's image on each patient's fundus, we evaluated the sequences of eye movements the patients make during(More)
To explain the veridical percept of the spatial ordering of objects and the generation of eye movements to peripheral targets, Lotze (1885 Microcosmos. Edinburgh: T. & T. Clark) proposed that there is a position label (local sign) for each retinal element. To estimate the precision of local sign information, we measured absolute localization thresholds at(More)
Two new, cost-effective thresholding algorithms for use in extracting binary images of characters from machine-or hand-printed documents are described. The creation of a binary representation from an analog image requires such algorithms to determine whether a point is converted into a binary one because it falls within a character stroke or a binary zero(More)
Increment-threshold spectral sensitivity functions were determined during the dominance and suppression phases of binocular rivalry. The shapes of the functions obtained during the dominance phase exhibited three maxima at approximately 440, 530, and 610 nanometers and resembled functions obtained for nonrivalrous control conditions. However, the functions(More)
We present a neural network model of short-term dynamics of the human horizontal vergence system (HVS) and compare its predictions qualitatively and quantitatively with a large variety of horizontal disparity vergence data. The model consists of seven functional stages, namely: (1) computation of instantaneous disparity; (2) generation of a disparity map;(More)
Contrast sensitivity functions (CSFs) were determined on a large group of patients with macular degeneration to better assess qualitative aspects of their residual vision. Contrast sensitivity was also determined through the telescopic low-vision aids of selected patients. In general, the patients have a substantial loss of contrast sensitivity for all(More)
PURPOSE Prolonged near work is considered to be an environmental factor leading to the development of late-onset myopia. Accommodation may be the specific mechanism underlying the association between near work and late-onset myopia. To determine whether late-onset myopes have abnormal accommodation, we compared accommodative static responses and dynamic(More)
Increment-threshold spectral sensitivity functions were determined for normal observers during binocular rivalry and for esotropic observers during strabismic suppression and under viewing conditions that normally induce binocular rivalry. Depending on the spatial and temporal properties of the test stimulus, the normal observers exhibited a(More)
PURPOSE Infantile nystagmus (IN) has been reported to decrease with convergence. However, previous studies reported equivocal results regarding a corresponding improvement in acuity with near viewing. The aim of this study was to determine whether visual acuity improves with near viewing in patients with IN. METHODS In the first experiment, visual(More)
In foveally fixating patients resolution acuity is approximately the same when measured with a Snellen chart (Snellen acuity) or when estimated from the high frequency cutoff of the contrast sensitivity function (CSF) (grating acuity). In contrast, with peripheral viewing, normal patients have better grating than Snellen acuity. This suggests that grating(More)