PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Vision, Monocular”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2006

Why Cyclops could not compete with Ulysses: monocular vision and mental images.

The present research demonstrates that the limitations of congenitally blind people in tasks requiring the processing of mental images are specifically related to the absence of binocular vision and not to the absence of vision per se. We contrasted three different groups of participants: sighted; visually impaired, with reduced binocular vision; monocular, with a normal visual acuity although in one eye only. Visually impaired participants (i.e. blurred vision) show a pattern of performance comparable to that of the sighted. In contrast, monocular participants show a similar pattern of performance to congenitally blind individuals despite being able to see perfectly well. These results shed new light on the relationship between perception and imagery and on the characteristics of sequential and simultaneous processes in the human brain.

Adult↗
PubMed2002

Monocular vision leads to a dissociation between grip force and grip aperture scaling during reach-to-grasp movements.

It has been argued that visual perception and the visual control of action depend upon functionally distinct and anatomically separable brain systems. Electrophysiological evidence indicates that binocular vision may be particularly important for the visuomotor processing within the posterior parietal cortex, and neuropsychological and psychophysical studies confirm that binocular vision is crucial for the accurate planning and control of prehension movements. An unresolved issue concerns the consequences for visuomotor processing of removing binocular vision. By one account, monocular viewing leads to reliance upon pictorial visual cues to calibrate grasping and results in disruption to normal size-constancy mechanisms. This proposal is based on the finding that maximum grip apertures are reduced with monocular vision. By a second account, monocular viewing results in the loss of binocular visual cues and leads to strategic changes in visuomotor processing by way of altered safety margins. This proposal is based on the finding that maximum grip apertures are increased with monocular vision. We measured both grip aperture and grip force during prehension movements executed with binocular and monocular viewing. We demonstrate that each of the above accounts may be correct and can be observed within the same task. Specifically, we show that, while grip apertures increase with monocular vision, consistent with altered visuomotor safety margins, maximum grip force is nevertheless reduced, consistent with a misperception of object size. These results are related to differences in visual processing required for calibrating grip aperture and grip force during reaching.

Adaptation, Physiological↗
PubMed2002

[Functional improvement after vision rehabilitation in low monocular vision after myopic macular degeneration and retinal detachment].

PURPOSE: We present a case of a 62 year-old woman, with a single eye functional vision (VA of 0.16) who improved her vision after following a vision rehabilitation program, which included optical and non-optical devices for daily performance. CONCLUSIONS: A correct optometric evaluation and a training program are key factors to improve quality of life in low vision patients, whose ocular pathology allows no other treatment.

Female↗
PubMed2002

[Time course of changes in cardiac rhythms in successful and unsuccessful solution of visual and motor tasks under the conditions of binocular and monocular visions].

The P. K. Anokhin theory of the general functional system considers integral behaviour as realization of processes aimed at reaching a useful result. Electrograms were recorded in students who were solving visual and motor puzzle tasks. Their results were estimated. There were two groups of subjects: 1) those with normal binocular vision and 2) those with monocular vision. Some specific features were found in cardiac rhythm power in each group. The findings suggest that there are relationships between the results of task solution, the type of visual perception, and heart rate parameters.

Adult↗
PubMed1975

Progressive changes in kitten striate cortex during monocular vision.

Following initial rearing in either total darkness or normal illumination, kittens at different ages were subjected to right-eye closure and various periods of vision through the left eye. After the period of monocular vision, single units in striate cortex were tested for visual responsiveness through each eye. A severe reduction in the proportion of units responsive to the deprived eye occurred over the first few days of monocular vision. Functional abnormalities were variably present after 1 day, marked after 2.5 and 3.5 days, and complete after 10 days. Monocular vision produced very much the same effect on ocular dominance of striate units, provided age and duration of suture were identical, regardless of whether kittens had received prior dark- or light-rearing.

Animals↗
PubMed2002

Acquired monocular vision: functional consequences from the patient's perspective.

PURPOSE: The study is conducted to determine the effect of acquired monocular vision (enucleation, phthisis) on the daily activities of patients. METHODS: Sixty-five patients in a case series completed a 30-question survey evaluating the functional consequences of monocular vision. RESULTS: Patients with sudden visual loss adapted more slowly than those with gradual loss (8.8 versus 3.6 months). Difficulties with depth perception and cosmesis were prevalent. Unexpected consequences included neck pain, strain with reading, employment change, depression, car accidents, and alcoholism. Ninety-one percent of patients had no formal training to help them adapt. CONCLUSIONS: More than previously appreciated, there are many obstacles that patients face in making the transition to monocular vision. Few patients receive any formal instruction to help them adapt, yet many indicate that it would be beneficial.

Activities of Daily Living↗
PubMed2006

Three presentations of monocular vision loss.

BACKGROUND: Carotid artery disease is estimated to affect 30% of persons older than 50. Risk factors include hypertension, cigarette smoking, hyperlipidemia and diabetes mellitus. Symptoms ascribed to carotid artery lesions with stenosis of the artery or plaque formation include monocular vision loss and transient ischemic attacks. Patients can present with transient monocular vision loss as their initial symptom. CASE REPORTS: Three patients from a geriatric clinic in Wilmington, Delaware presented with different complaints of vision loss with similar overall outcomes. Patient A was an 87-year-old woman who presented with dimming of vision on extreme left head turn. Dilated fundus examination found a retinal arterial emboli in the left eye (O.S.). Carotid duplex examination found 50% to 79% left internal carotid stenosis with no hemodynamic stenosis of the right internal carotid. Patient B was a 78-year-old woman who presented with a right superior altitudinal defect and transient vision loss in the right eye. Dilated fundus examination found retinal arterial emboli in the right eye (O.D.). Carotid duplex examination found 50% to 79% carotid stenosis in both the left and right internal carotids. Patient C was an 84-year-old man who complained of a superior altitudinal visual field defect O.D. Dilated fundus examination found a retinal arterial emboli O.D. Carotid duplex results showed calcified atherosclerotic plaques present at the level of the common carotid artery bifurcations bilaterally, with 50% to 70% narrowing of the right internal carotid artery with no significant narrowing of the left internal carotid artery. CONCLUSIONS: These 3 presentations show that in patients older than 50 who present with chief complaints of monocular vision loss, a differential diagnosis of carotid artery disease must be considered. Patients who exhibit retinal arterial emboli are at increased risk for stroke and vascular death. Appropriate measures for confirming a diagnosis include duplex ultrasound imaging, magnetic resonance angiography (MRA), and carotid angiography. Surgical techniques such as carotid angioplasty and carotid endarterectomy may be recommended.

Aged↗
PubMedDate not supplied

Layer differences in the effect of monocular vision in light- and dark-reared kittens.

We compared the effect of 2 days of monocular vision on the ocular dominance of cells in the visual cortex of light-reared kittens with the effect in dark-reared kittens at 6, 9, and 14 weeks of age, and analyzed the results by layer. The size of the ocular-dominance shift declined with age in all layers in light-reared animals. There was not a large change in the ocular-dominance shift with age in dark-reared animals in any layer, suggesting that dark rearing largely keeps the cortex in the immature 6-week state until 14 weeks or longer, although there was a slight decrease in layers II, III, and IV, and a slight increase in layers V and VI. At 14 weeks, the difference between light- and dark-reared animals was smallest in layer IV, larger in layers II/III, and largest in layers V/VI, suggesting that dark rearing has a large effect on intracortical synapses and a small effect on geniculocortical synapses. There was a significant ocular-dominance shift in layer IV at 14 weeks of age in both light- animals and dark-reared animals, showing that the critical period for ocular-dominance plasticity is not ended at this age. While the ocular-dominance shift after 26 h of monocular deprivation in 6-week animals was similar in light- and dark-reared animals, after 14 h it was smaller in dark-reared animals, showing that ocular-dominance changes occur more slowly in dark-reared animals at this age, in agreement with Mower (1991). Increases in selectivity for axis of movement after 26 h of monocular vision were seen in dark-reared animals at 6 weeks of age, but not at 9 or 14 weeks of age, showing that the critical period for axial selectivity ends earlier than the critical period for ocular dominance in dark-reared animals, as it does in light-reared animals.

Aging↗
PubMed2005

[Sensomotor learning and heart rhythm dynamics under the conditions of monocular vision].

According to P. K. Anokhin's general functional system theory, integral behavior is considered to be realization of processes directed towards achieving a useful result. The subjects of the study were a number of students, whose ECG was recorded while they were trained to fulfill a visual-motor task. Successfulness of learning was estimated. The study demonstrated a connection between the heart rhythm dynamics and the level of learning to fulfill visual-motor tasks.

Adolescent↗
PubMed2001

Behavioural responses of the tiger beetle larva to moving objects: role of binocular and monocular vision.

The larva of the tiger beetle Cicindela chinensis is an ambushing hunter with a body length of 15-22 mm that lives in a tunnel in the ground. It ambushes prey, keeping its head horizontal at the opening of the tunnel. When prey approaches the tunnel, the larva jumps to snap at it. When an object moves beyond its jumping range (approximately 15 mm), however, the larva quickly withdraws deep into the tunnel. These responses are mediated by two of six pairs of stemmata. How does the larva judge the hunting range using such a simple visual system? A previous study suggested that both binocular and monocular vision are used for distance estimation. Range estimation by binocular vision was further confirmed in the present behavioural observations: larvae jumped towards objects beyond the normal hunting range when virtual images of such distant objects were formed close to the larva using prisms or a narrow window. A possible mechanism involved in range estimation by monocular vision was also examined in behavioural experiments. The depth of the image in the retina appears to play a role in distance estimation because a larva with one functional stemma, the other stemmata being occluded, changed its response to a very distant object from an escape to a predatory jump when a concave lens was placed above its head. Two alternative ideas, based on optical and morphological data, are proposed to explain this behavioural change by the one-stemma larvae. First, as for myopic people, the larva might see clearly only objects that are close. Second, an infinitely distant object might produce a focused image only on the central part of the retina, whereas an object within hunting range (<15 mm) might do so on surrounding regions of the retina. The latter idea implies that the region of the retina at which the larva perceives a clear image is concerned with which type of behaviour is released, a predatory jump or an escape. We conclude that visual information about hunting range in the tiger beetle larva is extracted both peripherally by the spatial pattern of image clarity and centrally by binocular vision.

Animals↗