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At least 1,495 records · Page 83Linked to original sources
PubMed2000

Spectral analysis of adult dancers' sways: sex and interaction vision-proprioception.

In subjects of both sexes with or without dance training, dependence on vision and proprioception for postural control was studied by destabilizing these cues on a free seesaw. Fast Fourier transform processing allowed spectral frequency analysis of the platform sways recorded by an accelerometer. Two frequency bands of the total spectral energy were used: the lower (0 - 2 Hz) and the higher (2 - 20 Hz) frequency bands. Dancers were significantly less dependent on vision but use more proprioception than untrained subjects. Professional dance training appears to shift sensorimotor dominance from vision to proprioception, and this evolution seems more marked for males than females. Female and male dancers had similar dynamic performances, but for males, the better neuromuscular coordination may be associated with biomechanical factors.

Adult↗
PubMed1988

The contribution of vision and of sidedness to responses of the ankle musculature to continuous movement of the base of support.

Eight healthy women were subjected to continuous sinusoidal movements of the base of the platform on which they stood. Each subject was tested once in the anterior-posterior (AP) and once in the lateral movement direction. In the first 30 s of each test, subjects' eyes were open while during the following 30 s their eyes were closed. Bilateral EMG recordings from the Medical Gastrocnemius (MG) and the Tibialis Anterior (TA) muscles were continuously taken from the moment subjects became used to the imposed movement. Results revealed that during AP movements the MG and TA muscles were reciprocally activated and deactivated, thereby continuously stabilizing the ankle joint in advance of the imposed anterior or posterior perturbation. Similarly, during lateral movements each MG muscle was activated in the homologous side of the movement trajectory. These basic postural sets were neither affected by elimination of vision nor by sidedness. However, absence of vision caused decrease of the ratio between the IEMG of the MG muscle to that of the TA muscle during AP movements. This decrease resulted from decrease in the activity of the MG muscles and/or from increased activity of the TA muscles while vision was eliminated. The latter phenomenon occurred to a greater extent in the right leg.

Adult↗
PubMed1995

Diurnal variations in vision and relations to circadian melatonin secretion in multiple sclerosis.

It has long been recognized that symptoms of multiple sclerosis (MS) wax and wane with fluctuations occurring on an hour to-hour basis throughout a 24 hour period. It has been proposed that changes in circadian core body temperature, which alter axonal conductivity, may account for the fluctuations of symptoms in MS. A 51-year-old man with MS is reported in whom visual acuity deteriorated throughout the course of the day only to improve again at night between 10:00 p.m. and 2:00 a.m. These changes in vision were unrelated to rest or physical activity, but appeared to coincide with the circadian secretion of melatonin which is coupled to the circadian temperature rhythms. Since melatonin lowers body temperature, it is hypothesized that the nocturnal rise in melatonin secretion was related to improvement in vision in this patient. This hypothesis is supported by the observation that administration of melatonin (3 mg, orally) at 2:00 p.m., when the patient experienced severe blurring of vision, resulted within 15 minutes in a dramatic improvement in visual acuity and in normalization of the visual evoked potential latency after stimulation of the left eye. Moreover, since the pineal gland is a thermoregulatory organ which functions to prevent excessive rise of body temperature, it is possible that since MS is associated with dysfunction of the pineal gland, these patients may experience diminished capacity to eliminate heat at rest or during physical activity with resultant elevation of body temperatures which may further compromise neurologic functions by causing failure of axonal conduction.

Body Temperature↗
PubMed1975

Loss and recovery of vision with suprasellar meningiomas.

Central visual acuity losses were documented in a group of 23 patients with surgically and histologically verified suprasellar meningiomas. The pattern demonstrated was that of acute, gradual or fluctuating loss in one eye, followed by later loss of central acuity in the other eye. Both optic nerves and chiasm were invariably involved either by stretching or compression. Neither preoperative field abnormalities nor central acuity deficits could be correlated with the anatomical location of the tumor, nor could postoperative changes in vision be correlated with tumor size. Lengthy duration of acuity loss and severe visual deficit did not preclude postoperative recovery of vision. Improvement in sight most frequently occurred within the first several weeks after operation, and further return of vision was not noted after 1 year.

Blindness↗
PubMed2004

Intermittent vision and one-handed catching: the effect of general and specific task experience.

In Experiment 1, 15 skilled and 15 less skilled participants performed 1-handed catching in 4 conditions. For both groups, catching performance deteriorated significantly when no visual information was available for 40 ms between 20-ms visual samples (20/40) and continued to decline with subsequent increases in the duration between visual samples (i.e., 20/80 and 20/120). In Experiment 2, 50 participants performed a pretest and a posttest in a 20/80 condition, separated by 4 blocks of practice (N=80). Participants who practiced with intermittent vision (20/40, 20/80, and 20/120) exhibited a significant improvement between pretest and posttest. Although general practice with intermittent vision enabled some adaptation, posttest performance did not equal performance in the 1st block of continuous vision.

Adult↗
PubMed1998

A maximum motion technique for assessment of color vision defects.

Several luminance-matching methods, such as flicker fusion and the minimum motion technique (MMT), are capable of detecting certain forms of abnormal color vision. We present evidence that the heterochromatic fusion nystagmus (HFN) luminance matching technique can discriminate among normal trichromats, protanopes, and deuteranomals. The HFN luminance matching technique has the advantage that it provides a positive indication of isoluminance (maximization of motion) as opposed to the MMT and flicker fusion methods, which indicate isoluminance by the minimization of motion and flicker, respectively. We tested 16 normal trichromats, 6 protanopes, and 4 deuteranomals with the HFN technique. Results indicate that HFN is a useful tool for examining color vision. Because the HFN stimulus elicits reflexive eye movements (optokinetic nystagmus) that follow the apparent motion of the stimulus, HFN luminance matching will be particularly useful in animal and infant research, where other color vision tests are difficult to implement.

Adolescent↗
PubMed1998

Living with low vision. What you can do to help patients cope.

Patients with irreversible vision loss are understandably distressed, but physicians can help guide them to successful independent living. In this practical article, Dr Faye discusses the causes of low vision, offers tips for working with visually impaired patients in the office setting, and describes rehabilitation programs for such patients. A list of resources on low vision is also included.

Activities of Daily Living↗
PubMed1996

Night vision testing in unoperated eyes.

BACKGROUND: We previously described a simple test which evaluates image degradation in post-excimer laser (PRK) patients under scotopic conditions. After refractive surgery, corneal haze, ablation zone decentration, ablation zone/pupillary diameter disparity, and under-correction each result in a characteristic pattern on the Night Vision Recording Chart. METHODS: Using the same method, further studies evaluated night vision image degradation in 118 un-operated emmetropic, myopic, hyperopic, and astigmatic eyes and in 26 contact lens wearers. RESULTS: Scotopic image degradation increases with myopic refractive error, image displacement increases with astigmatism, and contact lens wearers have more image degradation that with spectacle correction. CONCLUSION: Our Night Vision Recording Chart offers a simple, reproducible method to characterize image degradation under scotopic conditions.

Contact Lenses↗
PubMed1995

Considerations in evaluation and treatment of the child with low vision.

Habilitation of infants and children with visual impairments should be based on a thorough understanding of their visual capabilities and limitations. Comprehensive evaluation of visual function includes measurement of visual acuity, contrast sensitivity, visual field, color vision, adaptation, visual sphere, accommodation, and oculomotor functions. It is best completed through a team approach that uses therapists, special educators, and physicians. A complete evaluation also includes examination of the effect of other motor functions on the use of vision. Nearly all aspects of a child's vision can be measured in play situations with tests that are easy to use. However, further education of nonphysician team members in refractive errors, optics, and function of optical devices may be necessary to ensure an accurate and thorough evaluation.

Adaptation, Ocular↗
PubMed1995

Low vision rehabilitation for a patient with a traumatic brain injury.

The client described in this article had undergone intensive rehabilitation for physical and cognitive deficits that resulted from an anoxic encephalopathy. Her recovery was good in all areas except visual functioning. Her reading and writing deficits were initially thought to result from visual-perceptual problems. A low vision evaluation identified the deficits as resulting from a macular visual field loss. Warren (1993) has proposed that an intact visual field is one of the basic components of vision that must be present before higher visual processing can occur. Until the macular perimetry was performed on this client, the extent of her central field loss was unknown, and the treatment that focused on the higher level visual processing was unsuccessful. The low vision program targeted the central field loss as the probable cause for her difficulties and an effective treatment protocol was established. The client was instructed regarding the nature of her visual field deficit and was trained in methods to compensate for this deficit. Although she has not returned to work as of this writing because of financial disincentives, the training resulted in a measurable and functional improvement in the client's ability to read continuous print text, a task she had not performed in 4 years, and in her ability to perform all writing tasks needed for daily living.

Adult↗
PubMed1999

Human cone pigment expressed in transgenic mice yields altered vision.

Genetically driven alterations in the complement of retinal photopigments are fundamental steps in the evolution of vision. We sought to determine how a newly added photopigment might impact vision by studying a transgenic mouse that expresses a human cone photopigment. Electroretinogram (ERG) measurements indicate that the added pigment works well, significantly changing spectral sensitivity without deleteriously affecting the operation of the native cone pigments. Visual capacities of the transgenic mice were established in behavioral tests. The new pigment was found to provide a significant expansion of the spectral range over which mice can perceive light, thus underlining the immediate utility of acquiring a new photopigment. The transgenic mouse also has the receptor basis for a novel color vision capacity, but tests show that potential was not realized. This failure likely reflects limitations in the organizational arrangement of the mouse retina.

Animals↗
PubMed1976

A training sequence for low vision patients.

A structured training program for teaching low vision patients to efficiently use their optical aids for reading tasks is presented. The arguments for the use of this particular training sequence is supported through the sample patient histories. The training sequences can be developed in any low vision practice and the materials are readily available. The importance of training in a low vision program is emphasized.

Adolescent↗
PubMed1976

The role of eye pathology in low vision evaluation.

The low vision patient's ultimate function and ability to profit from his rehabiliation are influenced by his eye disease. A discussion of low vision patient management uses as a basis the observation that greater success is evidenced when the low vision patient is treated in the context of his eye disease, visual acuity and his subsequent adjustment problems. The diagnosis, visual acuity and the visual field are explored as elements of a functional classification. The author classifies eye diseases according to the pattern of visual field loss: no loss of visual field; central or macular field loss; peripheral or perimacular field loss. Visual characteristics are then elaborated and case management is suggested in the context of each category.

Eye Diseases↗
PubMed1976

Training low vision patients.

The importance of training low vision-patients to use low vision aids is discussed. The team approach is emphasized and the advantages of the additional expertise considered. Specific procedures and techniques are are recommended to enhance the chances for success of the training program and it is concluded that training is an important aspect of follow-up care which should be made an intergral part of low vision care.

Aged↗
PubMed1999

Loss of vision from distant haemorrhage: report of four cases.

To describe the occurrence of visual loss from ischaemia of the optic nerve following distant haemorrhages. Four patients who sustained vision loss following distant haemorrhage, presenting to the neuro-ophthalmic clinic of the department of Ophthalmology, Addis Ababa University, from 1995 to 1997 were evaluated. The clinical presentation, management and prognosis are discussed. Post-haemorrhagic vision loss, other than being a rare occurrence, is under-reported due to the fact that these patients are very sick with massive blood loss and hence little attention is given to the vision loss by attending physicians and sometimes even the patients themselves. It is hoped that this paper will increase awareness about this condition among physicians attending to patients with severe bleeding and thus facilitate early diagnosis and referral.

Abortion, Spontaneous↗
PubMedDate not supplied

Measuring the effectiveness of bioptic telescopes for persons with central vision loss.

PURPOSE: 1) To evaluate a vision rehabilitation program aimed at training persons with central vision loss to use a bioptic telescope for improving life skills, including driving and 2) to compare the outcomes of subjects who are given bioptic telescopes and training, with subjects who are prescribed telescopic lenses without training. METHODS: Twenty-five subjects ranging in age from 16 to 78 years were included in the study. Each subject was randomized to one of three groups: Group 1 received bioptic telescopes and training during the first approximately 3-month-long period of the approximately 6-month-long study; Group 2 received lenses and training during the second approximately 3-month-long period of the study; and Group 3 received the lenses for approximately 3 months without any training. An assessment battery consisting of clinical vision tests, functional tasks evaluated by an orientation and mobility specialist, driving skills evaluated by a kinesiotherapist specializing in driver's education, and psychophysical measures was administered to Groups 1 and 2 at baseline, and at approximately 3 and 6 months, and to Group 3 at baseline and at approximately 3 months. The tasks were categorized into 6 major functional categories: Recognition, Mobility, Peripheral Identification, Scanning, Tracking, and Visual Memory. Training consisted of 5 weeks of laboratory-based training focusing on skills within these 6 categories, and 8 weeks of on-road driving training. RESULTS: There was significant improvement in all task categories with use of the telescopes. There was improvement in all task groups with training, though a significant difference between the trained and untrained groups existed only in the Recognition, Peripheral Identification, and Scanning Categories, but not in Mobility, Tracking, or Visual Memory. When the tasks involving driving-related skills were analyzed separately, training also had a significant effect. CONCLUSION: There was significant improvement in visual skills with the use of a bioptic telescope. This improvement was greater with training in the use of the lenses in a number of visual skills categories including driving-related skills.

Adolescent↗
PubMed2000

Color vision: a sensitive indicator of exposure to neurotoxins.

In the last 15 years an increasing number of studies have investigated color discrimination in workers exposed to various neurotoxins. Color vision was generally evaluated using the Lanthony D-15 desaturated panel (D-15 d), a test suited to identify mild acquired impairments, that can be easily performed at the workplace. In most studies, results were quantitatively expressed using the method of Bowman or that of Vingrys and King-Smith: the former is the most widely reported, while the latter gives information on the type of color defect. Applying D-15 d, or other color perception tests, impairment in color vision was observed among workers exposed to several solvents (styrene, perchloroethylene, toluene, n-hexane, and carbon disulfide), or to solvent mixtures, and also to metals like mercury. Chemical related color vision loss is a sub-clinical early effect, and in most studies proved dose-related. For styrene and perchloroethylene, and also for solvent mixtures, an impairment was observed at exposure levels lower than the current occupational limits, suggesting that these limits may be inadequate for a proper protection of visual function of workers.

Carbon Disulfide↗
PubMed2000

Veterans Affairs Multicenter Low Vision Enhancement System (LVES) study: clinical results. Report 1: effects of manual-focus LVES on visual acuity and contrast sensitivity.

PURPOSE: The Department of Veterans Affairs LVES Study is a multicenter study to determine the effectiveness of the Low Vision Enhancement System (LVES) as a visual rehabilitation device. The purpose of this study was to explore the efficacy of the Beta 1 manual-focus LVES for improving visual acuity and contrast sensitivity. METHODS: Patients whose visual acuity was 20/80 or worse in the better eye from any disease, who did not have significant visual field loss, who had previous low vision experience and were capable of working with the LVES were enrolled in a comprehensive prospective multicenter clinical evaluation. Initially, corrected spectacle visual acuities were measured using a standardized ETDRS chart. Contrast sensitivities were also measured with spectacle correction using a standardized Peli-Robson chart. These results were then compared to the acuities and contrast sensitivity obtained with the LVES at optimal magnification. Also, visual acuities were measured using an Eschenbach 3x spectacle-mounted binocular telescope, then compared to the acuities obtained using the LVES set at the lowest magnification (3x). RESULTS: All patients who completed the study demonstrated an improvement in visual acuity, with a median improvement of six lines of Snellen equivalent acuity using the LVES. Improvement in visual acuity was the same in both ARMD and non-ARMD causes of vision loss. Mean contrast sensitivity improved in 52 of 58 patients tested, with a mean improvement of 0.49 log units. CONCLUSION: The LVES significantly improves both visual acuity and contrast sensitivity in visually impaired patients who fall within the study criteria. Up to 10-fold improvement in visual acuity and up to 1.80 log units improvement in contrast sensitivity were noted in the study group when the LVES was used.

Adult↗