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PubMed1989

Vision calibrates sound localization in developing barn owls.

This study demonstrates that continuous exposure of baby barn owls to a displaced visual field causes a shift in sound localization in the direction of the visual displacement. This implies an innate dominance of vision over audition in the development and maintenance of sound localization. Twelve owls were raised from the first day of eye opening wearing binocular prisms that displaced the visual field to the right by 11 degrees, 23 degrees, or 34 degrees. The prisms were worn for periods of up to 7 months. Consistent with previous results (Knudsen and Knudsen, 1989a), owls reared with displacing prisms did not adjust head orientation to visual stimuli. While wearing prisms, owls consistently oriented the head to the right of visual targets, and, as soon as the prisms were removed, they oriented the head directly at visual targets, as do normal owls. In contrast, prism-reared owls did change head orientation to sound sources even though auditory cues were not altered significantly. Birds reared wearing 11 degrees or 23 degrees prisms oriented the head to the right of acoustic targets by an amount approximately equal to the optical displacement induced by the prisms. Birds raised wearing 34 degrees prisms adjusted sound localization by only about 50% of the optical displacement. Thus, visually guided adjustment of sound localization appears to be limited to about 20 degrees in azimuth. The data indicate that when confronted with consistently discordant localization information from the auditory and visual systems, developing owls use vision to calibrate associations of auditory localization cues with locations in space in an attempt to bring into alignment the perceived locations of auditory and visual stimuli emanating from a common source. Vision exerts this instructive influence on sound localization whether or not visual information is accurate.

Animals↗
PubMed1978

[Congenital color vision disorders in persons with mental disorders].

Colour vision was studied in 3000 mental patients (2000 males and 1000 females) with different diseases by means of polychromatic tables and a spectral anomaloscope AH-59. It was established that the frequency of genetically determined pathology of colour vision in patients (9,3% in males and 08,% in females) is similar to the pathology found in the general population and does not depend upon the clinical diagnosis. At the same time there was a large amount of patients with acquired disorders to colour perception (30% of the general pathology of colour vision).

Color Vision Defects↗
PubMed1979

Some influences of vision on susceptibility to motion sickness.

Two experiments were performed to evaluate the influence of vision on susceptibility to motion sickness during exposure to constant patterns of vestibular stimulation. The motion profile involved accelerating subjects at 20 degrees/s2 to 300 degrees/s, maintaining them at that constant velocity for 30 s, and decelerating them to a rapid stop in about 1.5 s. The number of stops tolerated by a subject before reaching the motion sickness endpoint served as his score. In Experiment 1, subjects were tested twice with their eyes open and twice with their eyes blindfolded. They tolerated fewer sudden stops when permitted sight of the experimental chamber. In Experiment 2, the effect of having the eyes-open or closed at different stages of the motion profile was evaluated. Having the eyes open during any stage of the test was more stressful than having the eyes closed, but this was especially true during the sudden stops. The findings are discussed in terms of their general implications for understanding a) situations in which vision alone elicits symptoms of motion sickness, and b) situations involving vestibular stimulation where vision heightens susceptibility.

Acceleration↗
PubMed1988

Are colour vision standards justified for the transport industry?

Colour vision standards are imposed in the road, rail, maritime and aviation industries and are often subject to vigorous opposition by those excluded by the standard. With greater emphasis in recent years on equality of opportunity, it is important that standards of personal fitness, such as colour vision standards, be subject to critical scrutiny. Such appraisal should be able to demonstrate that the community benefit arising from the application of the standard is sufficient to justify the personal and other costs of retaining the standard. This paper reviews the evidence relating to colour vision standards in the transport industries and concludes that a strong case can be made for their retention in public transport.

Accidents↗
PubMed1988

Visual search with non-foveal vision.

Experiments have been carried out to determine free visual search capabilities when an observer uses only peripheral vision. Foveal vision was eliminated by simulating a full foveal scotoma by means of a stabilized retinal image. Observers were asked to search an unstructured field for a single static target. Results from these experiments established that foveal vision plays a more significant role than is generally assumed in even the most basic of search tasks where the primary mechanism for target acquisition is assumed to be detection only. Results are discussed in terms of the visual lobes for the targets of search.

Fovea Centralis↗
PubMed1986

Binocular vision: its influence on the development of visual and postural reflex eye movements.

The time course for the development of binocular vision is similar to the time course for the development of mature, symmetrical, monocular optokinetic nystagmus in response to movements of the visual field in the nasalward or temporalward direction. If binocular vision does not develop normally, then the monocular optokinetic response remains immature, or asymmetric. This paper examines the connection between the development of symmetrical OKN and binocular vision, and relates how disturbances in visual development affect the ability of postural reflex eye movements to adapt to changes in the visual environment.

Adult↗
PubMed1986

Spectral sensitivity for observers with protanomalous, extreme protanomalous and protanopic colour vision.

Contemporary models of colour vision include a channel for luminosity arising from a combination of some or all of the cone outputs. Accordingly any alteration, reduction or loss at the cone level ought to affect the shape of the spectral sensitivity curve, yet there have been few reports of any significant differences being found between the curves of protanomalous and protanopic subjects. A modified minimum flicker technique was used to determine the spectral sensitivity curves of observers with protanomalous, extreme protanomalous and protanopic vision. Significant differences were found among the mean curves of these categories of vision from 550 nm upwards.

Adolescent↗
PubMed1987

Contribution of electroretinography to diagnosis of color vision deficiencies.

The role that electroretinography (ERG) has played in the past and might play in the future in the study of color vision deficiencies is discussed in this paper. First, an example is given of how Copenhaver and Gunkel concluded in 1958 the absence of the green cone system in deuteranopia before Rushton, with the more direct method of densitometry, reached the same conclusion. Padmos and van Norren showed in 1971 that chromatic adaptation did not change a dichromat's spectral sensitivity curve, which fits the model of a loss system. A comparison between dichromats' spectral sensitivity curves based on the rapid off-response and recent data on single monkey receptors showed a slight but systematic discrepancy, indicative of a rod contribution in the off-response method. Carriers of color vision deficiencies might be more readily detected with an ERG than with a psychophysical method. The early receptor potential (ERP) seems a less suitable means to study color vision deficiencies. The blue cones form an interesting subject of study since they seem to be the most vulnerable cone type. With an ERG method a localization of acquired tritan deficiencies is possible. A recent finding is that blue cones are substantially more sensitive to light damage than either rods, or red or green cones.

Color Vision Defects↗
PubMed1987

Vision loss in age-related maculopathy: primary care referral guide.

The primary care practitioner is frequently the first professional to whom the elderly patient will complain of blurred or distorted vision. The authors focus here on the leading cause of vision loss in the elderly--age-related macular degeneration (ARMD)--and the role of primary care in its detection and in referral for treatment. An overview of ARMD is presented, with discussion of pathophysiology, various forms of the disease, and available treatments. The importance of referral of these patients at the primary care level is noted. The authors also comment on patient education, low vision aids, and eye care for the disadvantaged.

Aged↗
PubMed1987

Impact of cataract surgery with lens implantation on vision and physical function in elderly patients.

We conducted a prospective study of 293 elderly patients undergoing cataract surgery with intraocular lens implantation to determine the impact of the surgery on vision and on subjective and objective measures of patient function. Visual acuity in the surgical eye improved from a mean of 20/100 before surgery to 20/40 four months after surgery; improvement was maintained at one year. Positive changes occurred in some subjective measures of patient function, such as reported activities of daily living and patient report of vision-dependent activities, but these changes were modest. The most marked changes in patient function occurred in objective measures of function. Mental status had improved not quite significantly at four months but significantly at one year. Timed manual performance improved dramatically and significantly at four months and one year. Cataract surgery was associated with improved vision and improved objective function in most patients by four months after surgery, and these improvements were maintained at one year.

Activities of Daily Living↗
PubMed1987

Effects of atropine and 2-PAM chloride on vision and performance in humans.

These experiments assessed the time course and severity of effects of atropine and 2-PAM chloride on selected visual functions, physiological measures, and a tracking performance task. Atropine up to 4 mg X 70 kg-1 body weight and 2-PAM Cl in doses up to 1200 mg X 70 kg-1 body weight were administered intramuscularly in a double-blind Latin square design. A long lasting and dose-related increase in pupillary diameter and decrease in accommodative amplitude with accompanying loss of near visual acuity was found following atropine administration. These functions returned to baseline 2 d after injection. Distance acuity, contrast sensitivity, color vision, and intraocular pressure showed no changes after atropine. Tracking performance was significantly decreased by 4 mg of atropine. The changes in vision function cannot readily explain the tracking performance loss, since the tracking involved a distant visual target while the atropine produced degradation of near vision. Most of the physiological tests, tracking performance and all visual functions were unaffected by 2-PAM Cl.

Accommodation, Ocular↗
PubMed1985

Patient use of low-vision aids after retinal detachment surgery.

Patient use of low-vision aids to improve postoperative vision was evaluated in 32 eyes after successful repair of retinal detachment that involved the macular area. Despite best-corrected postoperative visual acuity ranging from 5/155 to 10/38, both distance and near vision could be improved in all cases using telescopic and microscopic systems, respectively. Patient acceptance of the telescopic systems was 62%, and of the microscopic systems, 96%.

Adult↗
PubMed1985

[Practical experiences with very young children with vision disorders].

Very low vision or blindness affects the sensori-motor development of children. During infancy other exteroceptive stimuli like tactile and auditory stimuli, are being used as a substitute for the loss of vision. The very early motor signs of young neurologically normal infants, are based on this phenomenon. From a retrospective study of 30 very young low vision and blind infants some early motor signs are mentioned, as they can be used in diagnosis and treatment programs.

Acoustic Stimulation↗
PubMed1985

An itinerant model for delivery of clinical low vision services in a rural community.

In 1976, a premise was developed that resulted in the inception of a mobile low vision service in the State of New Hampshire. Today, the New Hampshire Association for the Blind continues to provide low vision service throughout the state using a mobile clinical van and a training staff who provide training in aid use within the home. The model has proved effective in dealing with the special needs of the low vision population in a rural area.

Community Health Services↗
PubMed1985

Gradual loss and recovery of vision in temporal arteritis.

Visual loss in temporal arteritis is usually sudden and irreversible. In this article, we describe a patient who complained of slowly progressive visual loss in one eye, eventually followed by loss of vision in the other eye and ophthalmoparesis. A biopsy specimen confirmed the diagnosis of temporal arteritis. Steroid therapy resulted in almost total recovery of vision. The gradual loss and recovery of vision is attributed to reversible ischemia of the optic nerve. This case broadens the spectrum of temporal arteritis to include complaints of progressive visual loss over several months.

Aged↗
PubMed1985

[Binocular vision in congenital glaucoma].

We have studied binocular vision in a group of 189 patients suffering from congenital glaucoma, before and after treatment, as well as the elements upon which vision depends. Therapeutic modalities, including occlusion are discussed. We insist on the possibility of recovering binocular vision in congenital glaucoma.

Amblyopia↗
PubMed1979

[The prism loupe spectacles used as low vision aid and in microsurgery (author's transl)].

In 1970 Biessels developed and constructed the new binocular prism loupe spectacles, mainly as improved low vision aids. They were derived from the Zeiss 8 x 20 prism binoculars, however, with different lenses and mechanical parts. They are quite different from the Galilean telescopic spectacles, hitherto available, with their lower mangifications, short working distances, chromatic aberration, and peripheral unsharpness. The Biessels prism loupes with variable magnification up to 12 times, and working distances of 18 to 30 cm, are mounted into spectacles. They provide for a comfortable stereoscopic vision with normal convergence. The visual field is virtually 20 cm at 25 cm distance, and sharp to the edges. The weight of a complete binocular prism loupe, including the frame, is from 100 to 110 grammes. In the past 7 years more than 500 of such visual aids have been delivered to low vision patients, half of them binocular, also 40 operating spectacles for microsurgery, all of them with great success. Here we report on the technical details and good results.

Eye Diseases↗
PubMed1979

Managing the low vision patient.

The low vision child has long been neglected by the professional community. A self-analysis of the usefulness of optometric service must be made as to professional attitudes and the understanding of the low vision aids as well as the patient that is expected to wear them. Once these hurdles are overcome, the optometrist is more able to help the low vision child become a productive, contributing member of society.

Child↗