Biomedical subjects

J H Seaber

Publications and source records attributed to J H Seaber.

12 recordsLinked to original sources

PubMed1989

McCollough aftereffects in strabismus and amblyopia.

In strabismic people, the functioning of the deviating eye is impaired. This impairment is binocular in origin since it depends on stimulation of the straight eye; sensitivity and acuity of the deviating eye are usually better when the straight eye is patched than when both eyes are viewing. We investigated interactions between the eyes in strabismic people by using the McCollough color aftereffect as an exploratory procedure. Both normal and strabismic people adapted to black and colored bars and then examined black and white test bars. They reported colors in the achromatic test bars that were complementary to the adapting colors; this is the McCollough aftereffect. Both a monocular McCollough effect and a binocular McCollough effect were induced in people having normal vision. Strabismic people did not show a binocular McCollough effect. Aftereffect strengths were the same in each eye of normal people but were stronger in the impaired eye of strabismic people. A speculation is offered as to why the "non-seeing" eye of strabismic people "sees" the aftereffect better.

Adaptation, Ocular↗

PubMed1987

Incidence and characteristics of McCollough aftereffects following video display terminal use.

After using video display terminals (VDT), some persons notice that achromatic patterns appear faintly colored hours after terminal use. We investigated the incidence of this effect, the McCollough effect (ME), among 125 VDT users. Subjects completed a questionnaire regarding work habits and certain life-style aspects. They were shown photographs of varying spatial frequencies to identify the adapting stimulus responsible for the ME. The incidence of ME after routine use of VDTs was 19.1%. The adapting stimulus was the repeating character lines of the VDT. No aspect of life-style investigated appeared to predispose an individual to develop the ME. Those subjects who developed the ME did not differ from those who did not in age, sleep, caffeine consumption, use of medication, refractive errors, or computer usage, nor did they have a higher incidence of ocular defects or eye strain.

Computer Systems↗

PubMed1982

Traumatic superior oblique palsies.

The differences in the clinical and diagnostic characteristics of 33 consecutive traumatic unilateral (21 patients, 62%) and bilateral (12 patients, 38%) superior oblique palsies were studied. The unilateral palsies had a large hypertropia in primary position, more vertical than torsional diplopia, a compensatory head tilt to obtain fusion, and a positive Bielschowsky head tilt test. In contrast, the bilateral palsies had small hypertropias in primary gaze that alternated on right and left gaze, a large V-pattern esotropia with excyclotorsion that was frequently bilateral, and a compensatory head position with fusion in upgaze. The results of the study indicate that a V-pattern in excess of 25 prism diopters, an excyclotorsion of greater than 10 degrees, or head trauma severe enough to cause loss of consciousness should also signal bilateral involvement. Torsional diplopia was present in only 20% of unilateral palsies vs 75% of bilateral palsies. The Bielschowsky head tilt test was diagnostic in 100% of the patients with unilateral palsy and 83% of the patients with bilateral palsy. It was undiagnostic in the supine position in all patients. Spontaneous resolution occurred in 65% of the unilateral palsies but in only 25% of the bilateral palsies. Surgical correction was successful in relieving persistent symptoms.

Adult↗

PubMed1981

Dyskinetic strabismus as a sign of cerebral palsy.

We found dyskinetic strabismus in 66 patients with cerebral palsy. The most striking feature of dyskinetic strabismus is the fluctuation from esotropia to exotropia under the same accommodative conditions with a slow tonic deviation similar to a vergence movement. With increasing age, exodeviation becomes more prevalent. Dyskinetic strabismus is seen exclusively in cerebral palsy patients. Many of these patients have an athetoid component to their disorder. The association of dyskinetic strabismus with athetosis and upward gaze palsy suggests that the basal ganglia may be the site of the malfunction. The strabismus responds poorly to surgery and the associated athetosis is important in the diagnosis and treatment of cerebral palsy.

Adolescent↗

PubMed1979