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PubMed1983

Involvement of GABAergic mechanisms in the optokinetic nystagmus of the frog.

Frog optokinetic nystagmus (OKN) was studied before and after an intravitreal injection of picrotoxin, a specific non-competitive GABA antagonist. In monocular vision, the OKN displayed a directional asymmetry favouring the Temporal-Nasal (T-N) stimulation. In that case, the nystagmus extinction frequency (NEF) is low, about 2 frames/s. In binocular vision, the OKN is symmetrical with a facilitation of performances compared to monocular vision (NEF = 3 frames/s). In monocular as in binocular vision, an intravitreal injection of picrotoxin (between 1 X 10(-4) and 5 X 10(-3) M) provoked the disappearance of the injected eye OKN and a spectacular facilitation in the performances of the intact eye, with the appearance of a N-T component and the increase of the NEF value reaching 7 or 11.5 frames/s according to the experimental conditions. This contralateral facilitation was no longer observed after the optic nerve of the injected eye had been cut, indicating that such a facilitation can only be explained by alterations of a central process triggered by the visual input. It is concluded that GABAergic mechanisms might be responsible for the inhibition of the N-T component in the frog OKN and might be involved in the control of the power of temporal resolution in this animal.

Animals↗
PubMed1991

Functional effects of bilateral form deprivation in monkeys.

Psychophysical methods were used to study the effects of binocular form deprivation, initiated at 1 month of age, on the visual sensitivities of young monkeys. All the monkeys reared with bilateral form deprivation for 7 weeks or longer had reduced spatial contrast sensitivity for both eyes. Although the contrast sensitivity deficits of the bilaterally form-deprived monkeys generally were larger for one eye than the other, the magnitudes of the deficits were small compared with those produced by similar periods of unilateral form deprivation. For other monocular vision functions investigated, temporal contrast sensitivity and increment-threshold spectral sensitivity, the data for the bilaterally form-deprived animals showed only minor variations from those of the control monkeys. However, none of the bilaterally form-deprived monkeys had binocular vision on either measures of binocular summation or stereodetection, even if the animal had normal monocular vision functions. Therefore, these results show that monocular sensory deficits caused by abnormal early visual experience as a result of bilateral form deprivation are much less severe than those caused by unilateral form deprivation. The differences in the severity of visual deficits may be attributed to the consequences of anomalous binocular competition associated with unilateral form deprivation that was minimized during bilateral form deprivation. Thus, these results illustrate that anomalous binocular competition is more detrimental to the developing visual system of infants than direct deprivation per se.

Amblyopia↗
PubMed2005

Lateralized visual behavior in bottlenose dolphins (Tursiops truncatus) performing audio-visual tasks: the right visual field advantage.

Analyzing cerebral asymmetries in various species helps in understanding brain organization. The left and right sides of the brain (lateralization) are involved in different cognitive and sensory functions. This study focuses on dolphin visual lateralization as expressed by spontaneous eye preference when performing a complex cognitive task; we examine lateralization when processing different visual stimuli displayed on an underwater touch-screen (two-dimensional figures, three-dimensional figures and dolphin/human video sequences). Three female bottlenose dolphins (Tursiops truncatus) were submitted to a 2-, 3- or 4-, choice visual/auditory discrimination problem, without any food reward: the subjects had to correctly match visual and acoustic stimuli together. In order to visualize and to touch the underwater target, the dolphins had to come close to the touch-screen and to position themselves using monocular vision (left or right eye) and/or binocular naso-ventral vision. The results showed an ability to associate simple visual forms and auditory information using an underwater touch-screen. Moreover, the subjects showed a spontaneous tendency to use monocular vision. Contrary to previous findings, our results did not clearly demonstrate right eye preference in spontaneous choice. However, the individuals' scores of correct answers were correlated with right eye vision, demonstrating the advantage of this visual field in visual information processing and suggesting a left hemispheric dominance. We also demonstrated that the nature of the presented visual stimulus does not seem to have any influence on the animals' monocular vision choice.

Acoustic Stimulation↗
PubMed1981

Comparison of the effects of dark rearing and binocular suture on development and plasticity of cat visual cortex.

Comparisons were made between the effects of binocular suture and dark rearing in terms of: (1) the state of visual cortical physiology after prolonged deprivation; and (2) the nature of physiological recovery seen when monocular vision was experienced after prolonged deprivation. These comparisons were based on the ocular dominance distribution and receptive field tuning characteristics of visual cortical cells. After prolonged dark rearing, most visual cortical cells were binocularly activated and had non-specific receptive field properties. Monocular vision after dark rearing produced dramatic changes: the majority of cells were responsive only to the open eye and these cells typically displayed orientation and direction selectivity. Prolonged binocular suture, on the other hand, resulted in a high incidence of unresponsive cells and cells with unmappable receptive fields, and a low proportion of binocularly responsive cells. Monocular vision experienced after binocular suture resulted in only slight physiological changes, and there was no evidence for selective development of connections from the open eye. These results indicate that dark rearing and binocular suture have different effects on the development of cat visual cortical cells. Diffuse visual stimulation through the sutured lids (binocular suture) appears to produce permanent developmental effects on cortical physiology, whereas complete deprivation (dark rearing) leaves cortex in a state which can be modified by subsequent visual experience.

Animals↗
PubMed1998

Four diopters prism test recording in small angle esotropia: a quantitative study using a magnetic search coil.

PURPOSE: To determine the vergence response, if any, in a homogenous group of patients suffering from strabismus and submitted to environmental induction of retinal disparity with respect to a control group of subjects. MATERIALS AND METHODS: A series of 13 subjects was included in the present study (5 normal subjects and 8 patients suffering from small angle esotropia). The patients were evaluated in an illuminated environment where they were told to stare at a target which subtended a visual angle of 20 degrees and, successively, in the dark using a luminous stimulus which subtended a visual angle of 3.5 minutes. The vergence movements were evaluated using a four diopter base-out prism; eye movements were recorded under conditions of both binocular and monocular vision. Ocular movements were recorded by means of a magnetic search coil; the amplitude and peak velocity of the vergence movements were evaluated by computer analysis. Statistical analysis was performed using the Multiple Anova test for repeated measures. RESULTS: The data obtained in the present study demonstrate that: 1) there is a significant difference between binocular and monocular vision in both groups of subjects; however, the ocular response in the patients affected by strabismus was significantly different from that in the control group of subjects; 2) during monocular vision in the dark, the response of the strabismic patients was highly variable; 3) for both groups of subjects no significant differences were observed in the vergence response when a large-angle stimulus was employed in light conditions nor when a small-angle stimulus was utilized in a dark environment.

Journal Article↗
PubMed1978

Is binocular vision always monocular?

Visual sensitivity of one eye was determined under binocular stimulus conditions yielding apparent fusion, stereopsis, monocular dominance, and monocular suppression. Marked losses in sensitivity accompanied monocular suppression but were not evident during stable singel vision. The results are inconsistent with the hypothesis that supression alone mediates binocular single vision.

Functional Laterality↗
PubMed2004

Difference scaling of gloss: nonlinearity, binocularity, and constancy.

Gloss is an attribute of visual appearance that originates from the geometrical distribution of the light reflected by the surface. We used the maximum likelihood difference scaling (MLDS) procedure (L.T. Maloney & J. N. Yang, 2003) to estimate gloss scales over an extended range. Observers' judgments were obtained for a series of 10 black, coated samples for two directions of illumination, in binocular and monocular vision. The results showed a nonlinear relation between gloss percept and instrumental specular gloss values. Sensitivity is higher at extreme scale values than in the middle. In binocular vision, the sensitivity to gloss is higher than in monocular vision exclusively for high gloss levels. Lastly, we found that gloss difference scales, when expressed in terms of the samples rather than the photometric characteristics, vary little with the direction of illumination. Gloss scaling thus seems to be independent of the geometrical variations of the luminous flux at the surface of the sample. By analogy with the term "color constancy," we call this property "gloss constancy."

Humans↗
PubMed1975

Optic organ and cervical proprioceptors in maintenance of body equilibrium.

Two experiments were made on the functional correlation between the optic organ and the cervical proprioceptors in maintenance of body equilibrium. Experiment I: The effects of weak and strong electric stimulation of the deep nuchal muscles on changes in optokinetic nystagmus and optokinetic after-nystagmus were examined in adult non-albino rabbits with binocular vision. Experiment II: Experiment I was repeated on rabbits with monocular vision giving optokinetic stimulation moving from the side of the blindfolded eye to that of the open eye and applying only weak electric stimulation to the neck muscles. The results obtained were as follows: (1) Experiment I: Weak electric stimulation of the deep nuchal muscles of rabbits with binocular vision tended to promote optokinetic nystagmus with either no significant change or decrease in optokinetic after-nystagmus. Strong electric stimulation had the opposite effects, i.e., it tended to inhibit optokinetic nystagmus and activate optokinetic after-nystagmus. It also produced abnormal optokinetic nystagmus, such as the inversion phenomenon of optokinetic nystagmus and "optokinetic nystagmus firing". (2) Experiment II: Weak electric stimulation of the deep nuchal muscles of rabbits with monocular vision had similar effects to those in experiment I, but promotion of optokinetic nystagmus was less obvious, while activation of optokinetic after-nystagmus was more marked. In addition, the inversion phenomenon of optokinetic nystagmus developed even on weak electric stimulation. From these results the following conclusions were drawn: (1) The cervical proprioceptors can function in two mechanisms causing promotion and break down of equilibrium of the optokinetic system. (2) The cervical proprioceptors, as an organ of equilibrium, can exert two different actions on the optokinetic eye reflexes, i.e., they can promote optokinetic nystagmus and inhibit optokinetic after-nystagmus.

Animals↗
PubMed1992

Correlations of memory and learning with vision in aged patients before and after a cataract operation.

The connection between memory and learning with vision was investigated by studying 100 cataract operation patients, aged 71 to 76 years, 25 of them being men and 75 women. The cataract operation restored sufficient acuity of vision for reading (minimum E-test value 0.40) to 79% of the subjects. Short-term memory was studied with series of numbers, homogenic and heterogenic inhibition, and long sentences. Learning was tested with paired-associate learning and word learning. Psychological symptoms were measured on the Brief Psychiatric Rating Scale and personality on the Mini-Mult MMPI. Memory and learning improved significantly when vision was normalized after the cataract operation. Poor memory and learning scores correlated with monocular vision before the operation and with defects in the field of vision, due to glaucoma and exceeding 20%, postsurgery. Monocular vision and defects in the visual field caused a continuous sense of abnormalness, which impaired old people's ability to concentrate on tasks of memory and learning. Cerebrovascular disturbances, beginning dementia, and moderate psychological symptoms obstructed memory and learning on both test rounds. Depression was the most important psychological symptom contributing to poor memory and learning scores after the cataract operation. The memory and learning defects mainly reflected disturbances in memorizing.

Aged↗
PubMed1989

[Monocular and binocular vision following lens implantation in traumatic cataract].

Lens implantation after surgery for traumatic cataract is a major help in rehabilitating the patient. Most such patients are still at work. Surgical problems result from injuries to the cornea, iris, lens, and vitreous body. If possible a posterior chamber lens should be implanted in the bag. In 35 patients, 24 posterior chamber lenses and 11 anterior chamber lenses were implanted. In 27 cases the traumatic cataract had been caused by perforating injury and in eight by contusion. In 28 patients there was a significant improvement in visual acuity by the day they were discharged. At short focus more than one-half of the patients had simultaneous vision with striated glasses, and two-fifths at long focus. Two-fifths of all patients attained stereoscopic vision at both short and long focus. The binocular functions were worse in most of the cases where the visual acuity of the injured eye was 0.4 or less.

Adult↗
PubMed2003

A case of acute loss of binocular vision and stereoscopic depth perception. (The misery of acute monovision, having been binocular for 68 years).

PURPOSE: There are few personal reports in the literature, by knowledgeable vision scientists, of the loss of binocular vision. This case is reported. CASE REPORT: This 68 year old retired pediatric ophthalmologist suffered an almost total loss of vision, OD, as a result of a sudden massive hemorrhage into the vitreous body from a bridging retinal vessel, which remained after repair of a spontaneous large horseshoe retinal tear. This caused significant problems with both remaining monocular vision, cognition, and space perception. It was surprisingly disabling. A diary is included. RESULT: The author now appreciates better: 1. that the overlap and cross compensation of monocular vision is quite significant; 2. that monocular depth perception may be impaired by any type of intervening optical media; 3. that a two dimensional world is very different and vastly inferior to a three dimensional world. COMMENT: Such problems are not ordinarily expected or described in these circumstances, but considering what is in the literature, they may be more common and serious than assumed by eye care professionals, and should be taken into consideration in rendering eye care in similar situations. Loss of binocular vision results in a significant handicap even when the vision remaining in the good dominant eye is normal. It is truly remarkable to this victim that so many mature patients are willing to accept this situation in the form of surgical or optical monovision to avoid spectacles for presbyopia.

Acute Disease↗
PubMed1978

Monocular peripheral vision as a factor in flight safety.

The performance of static visual identification tasks and simulated operational flying tasks, by nine binocular pilots and nine adapted monocular pilots, was measured in a unique operational visual simulator. It was hypothesized that, with head free to move, and adapted monocular pilot would perform as well as a binocular pilot, while an unadapted monocular (simulated by covering an eye) would perform less well. Other hypotheses were advanced. The static primary central task required sequential identification of dial readings. The dynamic primary central task involved simulated aircraft landing operations. During each set of primary tasks, a set of secondary peripheral visual tasks was performed. Results of the primary tasks and times of execution of the secondary tasks were subjected to analysis of variance. Factors included head position (fixed or free), stimulus location in peripheral field, eye state (seeing eye, blind eye), and type of central task (static, dynamic). All hypotheses were validated.

Accident Prevention↗
PubMed2003

Intermittent vision and one-handed catching: the temporal limits of binocular and monocular integration.

The aim of this research was to examine the temporal limits of binocular and monocular integration useful for one-handed catching. Participants performed 20 one-handed catching trials in 12 conditions (N = 240) defined according to the type of viewing (binocular, monocular) and the manipulation of the visual sample (continuous, intermittent). Catching performance deteriorated significantly when there was no visual information available for 80 ms between 20-ms visual samples provided simultaneously to each eye. However, there was no change in catching performance when continuous monocular vision was available for 80 ms between the binocular samples. Performance under monocular viewing decreased significantly when intermittent samples were separated by less than 20 ms. These results confirm that the equivocality in previously reported temporal limits of binocular integration is due to the different arrangement of the intermittent vision conditions and hence the information available between intermittent samples.

Adult↗
PubMed1985

Plasticity in cat visual cortex restored by electrical stimulation of the locus coeruleus.

It has been proposed that the presence of noradrenaline (NA)-containing terminals and NA-related receptors within the visual cortex is necessary to maintain the high level of neuronal plasticity in the immature visual cortex of kittens. In the present study we wanted to show whether electrical stimulation of the locus coeruleus (LC), which contains the somata of these cortical NA fibers, can restore neuronal plasticity to the normally aplastic visual cortex of juvenile and adult cats. We consistently found a significant loss of binocular cells in the visual cortex of mature animals which had monocular vision for only 12 h dispersed over 6 days (2 h a day, otherwise kept in the dark) in combination with concurrent LC stimulation. This result was interpreted as indicating that endogenous NA released from NA terminals restored susceptibility to monocular vision in the mature visual cortex. We next examined how long the restored plasticity lasts in the same animals after the LC stimulation was ended. The animals revived from the first recording session were either returned to the same daily schedule of brief monocular exposure (light/dark = 2/22 h) as before, or subjected to the usual monocular lid suture and kept in a cat colony environment (light/dark = 16/8 h). The LC electrodes had been removed and no more electrical stimulation was delivered at this stage. In the animals subjected to reiteration of brief monocular exposure, the state of reduced binocularity gradually returned to normal over a period of 2-3 weeks after stopping LC stimulation. We calculated that the revived plasticity disappeared at an average rate of a 22% loss every 7 days. This result sharply contrasted with the result obtained in the animals subjected to usual monocular lid suture. In this test the state of reduced binocularity continued for at least the next 3 weeks, suggesting that the restored plasticity was sustained throughout a period of 3 weeks (longest term tested). The different results obtained in the two paradigms may be explained by the different strength of binocular imbalance in the two tests imposed on the visual cortex in which neuronal plasticity was restored partially.

Animals↗
PubMed1994

Vision evaluation in people with Down's syndrome.

We tested the colour vision of 72 people with Down's syndrome using the Ishihara test and an anomaloscope. We found that 13 of the subjects, 6 males and 7 females, had defective colour vision according to Pickford's classification. In monocular vision 10 eyes were protan (five simple, three extreme and two deviant), one eye was simple deuteranomalous and the remaining eyes were normal: in binocular vision four of the subjects were protan (two simple and two deviant), two subjects were deutan (one simple and one deviant) and the rest were normal. Many of our subjects had lens opacities, strabismus, nystagmus, hypermetropia, high myopia and astigmatism, confirming literature reports. The contrast sensitivity function measured with the VCTS test showed a considerable loss of low-frequency sensitivity in our subjects compared to a normal population, which was more marked in the more severely impaired subjects.

Adolescent↗
PubMed2000

Distortions in definite distance and shape perception as measured by reaching without and with haptic feedback.

Psychophysical studies reveal distortions in perception of distance and shape. Are reaches calibrated to eliminate distortions? Participants reached to the front, side, or back of a target sphere. In Experiment 1, feedforward reaches yielded distortion and outward drift. In Experiment 2, haptic feedback corrected distortions and instability. In Experiment 3, feedforward reaches with only haptic experience of targets replicated the shape distortions but drifted inward. This showed that outward drift in Experiment 1 was visually driven. In Experiment 4, visually guided reaches were accurate when participants used binocular vision but when they used monocular vision, reaches were distorted. Haptic feedback corrected inaccuracy and instability of distance but did not correct monocular shape distortions. Dynamic binocular vision is representative and accurate and merits further study.

Adult↗
PubMed1993

Monocular nystagmus caused by unilateral anterior visual-pathway disease.

The authors examined five young children with monocular vision loss who developed monocular nystagmus. The nystagmus was of fast frequency and small amplitude in all fields of gaze. In four children, successful treatment of the cause of the vision loss resulted in cessation of the nystagmus. No child showed signs of spasmus nutans, or of optic nerve or chiasmal tumor. The evaluation of the young child with unilateral nystagmus should begin with a careful eye examination.

Eye Diseases↗