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At least 883 records · Page 49Linked to original sources
PubMed1983

The H1-antagonist mequitazine: studies on performance and visual function.

The effects of single oral doses of mequitazine (5 and 10 mg), terfenadine (60 mg) and triprolidine (10 mg) as active controls, and placebo were evaluated on visuo-motor coordination, digit symbol substitution, critical flicker fusion and dynamic visual acuity, and on subjective assessments of mood and well-being in six normal female volunteers. The study was double-blind. Mequitazine (5 mg) impaired visuo-motor coordination 7.5 h after ingestion (considered to be a chance result), but there was no effect on digit symbol substitution, critical flicker fusion threshold or dynamic visual acuity. Mequitazine (10 mg) impaired visuo-motor coordination and reduced the number of substitutions on the digit symbol substitution test. Terfenadine (60 mg) had no effect on performance or on subjective feelings. Triprolidine (10 mg) impaired visuo-motor coordination, reduced the number of substitutions on the digit symbol test, lowered the critical flicker fusion threshold and reduced dynamic visual acuity. Mequitazine (5 mg) and terfenadine (60 mg) are likely to prove acceptable H1 antagonists when sedation must be avoided.

Adult↗
PubMed2003

Objective measurement of visual function in glaucoma.

Of the objective (electrophysiological), functional tests of glaucomatous damage, three hold the most promise. Some evidence suggests that the pattern electroretinogram, the photopic negative response of the electroretinogram, and the multifocal visual-evoked potential can detect early glaucomatous damage, damage that may be missed on static automated achromatic perimetry. However, in their current forms, these tests can supplement, but cannot replace, static automated achromatic perimetry. Further, the multifocal visual-evoked potential is the only one of these tests that supplies topographic information about local damage. In addition, we still lack a complete understanding of the relation between these tests and the underlying damage to ganglion cells. In this context, it has recently been suggested that the signal in the multifocal visual-evoked potential response may be linearly related to the loss of ganglion cells. Finally, more information is needed about these tests from longitudinal or prospective studies.

Electroretinography↗
PubMed2003

Effects of scleral search coil wear on visual function.

PURPOSE: The scleral search coil is widely regarded as the gold standard measurement technique for eye movements. The effect of wearing scleral search coils on human vision has not been systematically studied. However, there are anecdotal reports of degraded visual acuity, mild eye irritation, and an increase rise in intraocular pressure (IOP). The current study was conducted to investigate the effect of scleral search coil use on visual acuity and ocular integrity. METHODS: Six subjects were examined; all had previously worn search coils. Two drops of topical anesthetic were administered before insertion of the coils. Coils were inserted by hand and secured by applying mild pressure. The coils were removed after 45 minutes or on request of either the subject or the clinician. Before, during (at 15-minutes intervals), and after the coil was worn, the following measurements were taken for both eyes: tonometry (noncontact), corneal topography, biomicroscopic examination, visual acuity (monocular Snellen), and an eye-discomfort rating. RESULTS: Scleral coils produced a variety of effects, including ocular discomfort, hyperemia of the bulbar conjunctiva, increased IOP, buckling of the iris, grade 2 and 3 corneal staining, and reduction in visual acuity. Effects appeared as early as 15 minutes after insertion of the coils. All observed effects seemed to be transient and dissipated after coils were removed. CONCLUSIONS: Scleral coils may not be appropriate for all subjects. The findings suggest that there is a need for thorough subject prescreening and that clinicians should consider the risk/benefit ratio. Acute reduction in visual acuity may confound search coil findings. More research is needed to determine the maximum wearing time for properly screened subjects.

Adult↗
PubMed1991

Cortical development and visual function.

Hypotheses are advanced regarding some of the processes underlying the development of an accurate retinotopic map in striate cortex, and the development of cortical magnification. In the first case it is suggested that competitive pruning of afferent synapses may be important in the increase in grating acuity seen in infancy, and that this process may be disrupted in anisometropic amblyopia. In the second it is argued that the development of vernier acuity in infancy may reflect changes in cortical magnification, and that this may be due to increasing functional independence of the columnar units in striate cortex.

Humans↗
PubMedDate not supplied

[An experiment in using Sternberg's paradigm in studying cognitive visual functions in man].

Sternberg's technique of additive factors was used. Subjects had to define whether the test and the standard stimuli were identical or not by pressing one of two buttons. Reaction time was shorter in the trials with identical stimuli than in the trials with different ones. Three factors were shown to underly the difference. First, the duration of comparison of visual images under the same and different conditions was not equal. Second, there were fewer comparisons in the trials with identical stimuli. Third, the duration of comparison of stimuli and the number of comparisons could affect other stages of perceptual task.

Adult↗
PubMed1996

Long-term fluctuation of relative afferent pupillary defect in subjects with normal visual function.

PURPOSE: To determine whether the relative afferent pupillary defect (RAPD) remains constant over time in normal subjects. METHODS: Seventeen normal subjects were tested with infrared pupillography and automated perimetry in four sessions over 3 years. The changes in RAPD and visual field asymmetry between testing sessions were compared. RESULTS: The range of RAPD was 0.0 to 0.3 log unit, and the difference in the mean deviation between the eyes on automated static perimetry was 0 to 3 dB. Eight subjects repeatedly had an RAPD in the same eye. There was no correlation between the RAPD and the visual field asymmetry at the same visit. Changes in the magnitude of the RAPD between any two sessions were typically small (median, 0.08 log unit; 25th percentile, 0.04 log unit; 75th percentile, 0.15 log unit). CONCLUSIONS: Some normal subjects may show a persistent but small RAPD in the absence of detectable pathologic disease. Therefore, an isolated RAPD in the range of 0.3 log unit that is not associated with any other significant historical or clinical finding should probably be considered benign.

Adult↗
PubMed1989

Objective investigation of visual function using a nondestructive zoom-FFT technique for evoked potential analysis.

We describe an ultra-high resolution technique for recording evoked potentials (EPs) that are thousands of times smaller than the total EEG power. We report that two superimposed visual stimulus patterns, one modulated at F1 Hz and the other at F2 Hz, can generate 20 or more EP frequency components, each of which is contained within a bandwidth of no more than 0.004 Hz. We have developed a theoretical method for calculating the amplitudes and phases of these various cross-modulation components for different arrangements of model neurons. The relative amplitude of the various cross-modulation components seems to be a 'signature' of the particular neural model and this offers a way of testing theoretical neural models against EP data. As an illustration we compare the nonlinear EP components evoked by dichoptic stimulation with unpatterned flickering light against several models of binocular interaction. These nonlinear binocular interaction terms may offer a means of investigating binocularity in amblyopic children or infants who have low acuity in one or both eyes.

Electronic Data Processing↗
PubMedDate not supplied

Visual functions of drivers involved in traffic accidents.

Eye functions were studied in 56 drivers who had recently been involved in traffic accidents. There were 17 women and 39 men in the study group, aged 20-87 years. The traffic accidents had happened in intersections and city streets, in parking places and on highways. In seven drivers, a visual impairment was found: two drivers had strabismus and low visual acuities in one or both eyes, two had considerable hyperphoria, and three had a deutan color vision defect. However, comparing the type of accident to the defective eye functions showed no probable correlation.

Accidents, Traffic↗
PubMed1989

Interocular asymmetry of visual function in heterozygotes of X-linked retinitis pigmentosa.

Heterozygotes of X-linked retinitis pigmentosa were studied with full field rod and cone electroretinography and light adapted kinetic perimetry. Twelve parameters from the electroretinograms (ERGs) and two parameters from the kinetic visual fields of both eyes of 22 heterozygotes were measured and statistical comparisons made with results from female control subjects. Rod and cone ERG amplitude parameters were significantly lower and cone timing delayed in the heterozygotes. Most of the ERG parameters that were abnormal in measured value also showed significantly greater interocular differences compared with controls. Kinetic visual fields with both V-4e and I-4e test targets were smaller in heterozygotes than in controls. Only with the I-4e target, however, were interocular differences significantly larger in the heterozygotes. For the I-4e target and many of the ERG parameters, using the interocular difference in conjunction with the measured parameter value from a single eye significantly increased the efficacy of discrimination between heterozygotes and controls; for some ERG parameters, the interocular difference alone provided the best separation of the two groups.

Adolescent↗