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Biomedical subjects

J M Wolfe

Publications and source records attributed to J M Wolfe.

65 records · Page 4Linked to original sources
PubMed1981

Is accommodation colorblind? Focusing chromatic contours.

Two adjacent regions define an edge if they differ in either color or luminance. If the difference is purely chromatic, the edge is said to be isoluminant. Isoluminant contours are often perceptually unstable. Perhaps some of this instability could be explained if isoluminant contours were difficult to bring into focus. To test this hypothesis, a vernier optometer was used to measure the accuracy of steady-state accommodation for the vertical boundary of a red-green bipartite field. This edge was presented at optical distances of 0, 1.5, 3.0, and 4.5 diopters, with brightness contrasts between the two hemifields of 0% (isoluminant), 15%, 58%, and 100%. Accommodation was essentially unresponsiveness to the isoluminant edge and exhibited increasing focusing accuracy with increased brightness contrast. Control experiments replicated this finding for red-orange, green-blue, and white-white fields. These results imply that luminance contrast is a necessary stimulus for monocular accommodation. Inappropriate accommodation may be a factor contributing to the perceptual instability of isoluminant patterns.

Accommodation, Ocular↗
PubMed1980

Quick assessment of preferential looking acuity in infants.

A simple and rapid method for assessing the visual acuity of infants can be a valuable tool for eye care specialists as well as for researchers in vision. We have developed a preferential looking (PL) procedure that uses simple equipment to obtain measures of PL acuity in a few minutes. Infants ranging in age from 2 weeks to 1 year can be tested. Sessions on infants without any visual problems are completed in less than 5 min. Computer simulations of the technique show that the fast procedure attains almost 80% accuracy in assessing infants' PL acuity thresholds. When PL acuity thresholds obtained by the 60-trial method of constant stimuli were compared to those obtained by the fast method on the same infants, they were identical on 70% of the sessions and only off by one-half octave in an additional 20% of the sessions. Interobserver reliability was also high. The ease and rapidity of the procedure make it appropriate for use in the clinic.

Age Factors↗
PubMed1979

Evidence for separable binocular processes differentially affected by artificially induced anisometropia.

Two measurable effects are produced by viewing a large disk rotating about the line of sight: a perceived displacement of the apparent horizon (tilt) and cyclotorsion of the eye (torsion). Previous results in our laboratory (see Refs.) using dichoptic presentation techniques show that both effects demonstrate binocular enhancement in normal subjects. Further, stereoblind subjects maintain enhancement for the oculomotor effect, torsion, but not for the perceptual effect, tilt. In this study we have found that this stereoblind pattern of results can be produced optically in normals by introducing a three diopter myopia in one eye. This renders the subject stereoblind and causes suppression of the artificially myopic eye. In this condition torsion still shows enhancement; tilt does not. This procedure may be useful in isolating causes of stereoblindness and in locating different sites of binocular interaction.

Adult↗
PubMedDate not supplied

Vocal cord dysfunction mimicking a severe asthma attack.

Vocal cord dysfunction is a rare type of airway obstruction that may mimic an acute asthma attack. We present a case of a patient who arrived in the Emergency Department (ED) in acute respiratory distress, with a history of severe asthma requiring previous intubation, who was diagnosed with vocal cord dysfunction by bronchoscopy in the ED.

Adult↗