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PubMed2003

[Phantom vision sensation].

The paper presents the phenomenon of phantom sensation including in particular, a phantom vision. These unusual sensations occur among the blind (or almost blind) and are characterised by the perception of various visual impressions, for example, light, geometrical shapes, buildings, people, flowers etc. The paper presents views explaining the generation of phantom vision. According to Melzack's theory, the occurrence of these sensations is explained in relation to the phenomenon of transforming the neuro-activity of the brain in a specific--for each organ--neuronal network called neuromatrix. Even if some organs do exist but have ceased to function completely (or to a significant degree) and consequently the brain does not receive any sensory stimuli from them, the neuromatrix in brain can generate visual sensations constituting the phantom vision phenomenon. The article also includes commentaries on such visual and mental sensations like hallucinations, Pick's visions and so called "scotoma of the leg".

Humans↗
PubMed2004

Adaptations in horizontal head stabilization in response to altered vision and gaze during natural walking.

The purpose of this study was to determine adaptations in head stability resulting from altered gaze control and vision during over-ground walking. Using over-ground walking permitted adaptations in walking velocity and cadence that are otherwise not possible during treadmill walking or walking-in-place. Gaze control and vision were manipulated by having 20 young adult subjects 1) walk naturally, 2) view a distant, earth-fixed target to enhance the vestibulo-ocular reflex (VOR), 3) view a head-fixed target to suppress the VOR, and 4) walk in darkness. Horizontal head and trunk angular velocities in space, walking velocity and cadence were measured. Root-mean-square head and trunk angular velocities were calculated and frequency analyses determined head-trunk movement patterns. Results demonstrated that when given the opportunity, subjects slowed down and decreased cadence in response to challenging tasks. Despite strongly reduced walking velocity and cadence, walking in darkness proved most challenging for head stabilization, indicating the importance of vision during this process. Viewing the earth-fixed target demonstrated the greatest head stability thereby, facilitating gaze stabilization. However, comparisons between the earth-fixed and head-fixed target conditions suggest a reciprocal relationship where gaze stability also facilitates head stability. This contribution of gaze stability to head stability is more important than vision alone as the head stabilization response was diminished during the VOR suppressed condition.

Adaptation, Physiological↗
PubMed1992

Preschool vision screening in pediatric practice: a study from the Pediatric Research in Office Settings (PROS) Network. American Academy of Pediatrics.

In this cross-sectional study, the vision-screening process is described for 8417 children aged 3 to 5 seen for health supervision in a group of 102 pediatric practices in 23 states and Puerto Rico. Three hundred forty children who failed screening (63% of those who failed) were followed up 2 months after initial screening. The sample was 52% male, 86% white, 9% black, 3% Hispanic, and 1% Asian. Vision screening was attempted on 66% of children overall. Pediatricians' reasons for not screening were "not routine" (44%), "too young" (40%), and "screening done previously" (17%). Younger children were less likely to be screened than older children (39% of those aged 3), and Hispanics were less likely to be screened than other ethnic groups (P less than .001). Thirty-three percent of children received no screening for latent strabismus. Two months later, 50% of parents whose child had failed a vision test were unaware of this fact on questionnaire follow-up. Eighty-five percent of children referred to an eye specialist had made or kept an appointment. It is concluded that pediatricians need to increase vision screening among younger preschool children and communicate more effectively to parents the results of screening failure.

Amblyopia↗
PubMed2005

Mobile phone related-hazards and subjective hearing and vision symptoms in the Saudi population.

OBJECTIVES: Over the past decade utilization of mobile phones has dramatically increased. They are now an essential part of business, commerce, and communication, however, their use may lead to health problems. Therefore, the present study was designed to investigate a link between the use of mobile phones and hearing and vision symptoms in the Saudi population and also to contribute to the increase in social awareness of health problems associated with the use of these devices. MATERIALS AND METHODS: A total of 873 (57.04% of males and 39.86% of females) subjects using mobile phones were invited to participate in the presented study. A structured questionnaire was distributed among them to collect a detailed medical history. The Chi-square test was employed to observe the relationship between duration of calls and hearing and vision complaints. RESULTS: The present study showed an association between the use of mobile phones and hearing and vision complaints. About 34.59% of problems were related with impaired hearing, ear ache and/or warmth on the ear, and 5.04% of complaints with the decreased and/or blurred vision. CONCLUSIONS: It is concluded that the use of mobile phone is a health risk factor, and thus it is suggested that excessive use of mobile phones should be avoided and social awareness increased through health promotion activities, such as group discussions or public presentations and via electronic and printed media sources.

Adolescent↗
PubMed1992

Color vision in dominant optic atrophy.

The color vision of seven patients with dominant optic atrophy in four different families was studied with the following color vision tests: the Standard Pseudoisochromatic Plates part 2, the Lanthony Tritan Album, the Velhagen Pflügertrident plates, and Farnsworth Panel D 15, the Farnsworth-Munsell 100 hue test, the Nagel anomaloscope, and the Besancon anomalometer. In the first family, the mother, one of the sons, and one of the grandsons were affected. The mother had a deutantritan defect; the son and the grandson both had an undefined red-green and a tritan defect. In the third family, the mother and the son were affected. Only the color vision of the son could be examined. He had a tritan defect. In the fourth family, the mother and the daughter were affected. Both had a deutan defect. In the diagnosis of dominant optic atrophy, it must be remembered that not only blue color vision defects occur, but that other kinds of defects are also possible.

Adult↗
PubMed2006

Color vision assessment: fail rates of two versions of the Farnsworth lantern test.

INTRODUCTION: The Farnsworth lantern test has long been used to assess the color vision of those seeking to enter the aviation industry and other occupations that require recognition of signal lights. A new version of the Farnsworth lantern, the Optec 900, is now produced because the original version is no longer manufactured. This paper reports the pass/ fail rates of a production model of the new version compared with an original one. METHODS: There were 100 male subjects with abnormal color vision who were given 3 runs with each lantern test. Their color vision deficiency was diagnosed using a battery of tests including the D15 test and the Nagel anomaloscope. RESULTS: A total of 19% passed the new lantern test compared with 24% for the original Farnsworth using the usual fail criteria. The pass rates become 17% and 21%, respectively, when adjusted for the expected proportions of the types of abnormal color vision. There was agreement between the two lantern tests for 89% of subjects: 8% passed the old Farnsworth and failed the new version, and 3% failed the original Farnsworth and passed the new. There was a practice effect: when one lantern was passed and the other failed, the lantern passed was, with one exception, given second. Both lantern tests passed subjects who made no errors on the first run who subsequently made many errors when given further runs. Only 4% of subjects made no errors on all runs. CONCLUSION: The Optec 900 can be considered equivalent to the Farnsworth lantern and might be preferred because it is slightly more stringent, reducing the risk of passing those who will make errors with signal lights. The practice of passing applicants who make no errors on the first run should be abandoned since 10% of those who pass in this way make many errors when additional runs are given.

Adolescent↗
PubMed2006

[Visual acuity and binocular vision in children with pseudophakia].

PURPOSE: To evaluate the results of cataract surgery in children with IOL implantation. MATERIALS AND METHODS: Our research involved 106 children (156 eyes) with congenital and traumatic cataract, in age from 18 months to 18 years, who underwent cataract surgery with intraocular lens implantation. We evaluated visual acuity for far vision and binocular vision after surgery. RESULTS: Visual acuity over 0.5 in unilateral congenital cataract was found in 27.25%, in traumatic cataract in 73%, whereas in bilateral congenital cataract visual acuity over 0.5 we received in 75% of operated children. Full binocular vision was obtained in children with good visual acuity (0.5 and more), with appropriate alignment of the eyes: 13.1% in unilateral congenital cataract, 45.4% in traumatic cataract and 55% in congenital bilateral cataract. CONCLUSIONS: Cataract surgery with intraocular lens implantation results in increase of visual acuity and in achievement binocular vision, if surgery is carried out in the early period, after it had been diagnosed.

Adolescent↗
PubMed2007

Can color vision defective subjects who pass the farnsworth lantern test recognize surface color codes?

INTRODUCTION: The International Civil Aviation Organization requires that pilots be able to distinguish the colors used in air navigation and in particular be able to identify the colors of signal lights. Most national aviation authorities use a lantern test to assess the ability of applicants for a pilot's license who have abnormal color vision to recognize the colors of signal lights. However, color-coding is now widely used in aviation systems other than signal lights. Color is used in tarmac markings, maps, manuals, and electronic flight instrument displays. These color codes can use 10 or more colors, many more than the 3 to 5 used for signal lights. This study investigated whether people with defective color vision (DCV) who pass the Farnsworth lantern test can recognize the main colors used for surface color codes. METHODS: There were 99 subjects with DCV who were tested using the Optec 900 version of the Farnsworth lantern test and also named the colors of a set of 10 surface colors that varied in shape (dots and lines) and size (3 sizes; angular diameters 0.27, 1.0, and 2.4 degrees; angular widths 0.14, 0.27, and 0.50 degrees). A control group of 20 subjects with normal color vision also named the surface colors. RESULTS: Of the DCV subjects, 19% passed the Farnsworth lantern test, of whom 74% made no errors with the surface colors. The other 26% made few errors (up to 5 errors in 120 presentations) and those errors were mostly to confuse red, orange, and brown. The subjects with normal color vision made no errors naming the surface colors. CONCLUSION: Those who pass the Farnsworth lantern test can recognize the colors of a 10-color surface color code with few or no errors. This is because the small (2.9-min arc) stimulus of the lantern test presents a more difficult task than the larger surface colors.

Adolescent↗
PubMed1991

Low vision rehabilitation. Finding capable people behind damaged eyeballs.

Loss of vision is a common physical impairment in America today. Comprehensive low vision rehabilitation programs can have dramatic results in increasing the independence and productivity of affected persons. Rehabilitation efforts must be tailored to the type of vision loss and to specific functional implications. Every effort should be made to enhance the residual vision. Activities of daily living, orientation and mobility, and psychological concerns must be addressed.

Activities of Daily Living↗
PubMed1991

[Assessment of vision using a computer].

1. The authors elaborated and tested a computer method for assessment of vision. This method is compatible with the basic procedure for assessment of vision and its variability. 2. The authors recommend to supplement values of vision by the parameter of line steepness. This parameter is independent on the value of vision and gives the number of normalized lines on which the number of correctly assessed optotypes declines from 95 to 5%.

Adult↗
PubMedDate not supplied

Low vision: the forgotten treatment.

Low vision is subnormal visual acuity or abnormal visual field resulting from a disorder in the visual system that cannot be corrected with ordinary eye glasses or by medical or surgical intervention. The major causes for low vision are macular degeneration, diabetic retinopathy, glaucoma, and cataracts. Low vision devices are often helpful for all of these causes. A low vision comprehensive visual rehabilitation examination usually includes initial interviews with patients and their families, with an emphasis on the patients' goals and realistic expectations of what they want to achieve.

Aged↗
PubMed1990

Color vision defect as first symptom of progressive cone-rod dystrophy.

A 15-year-old girl complained of color vision difficulties and was found to have an acquired color vision defect with no other abnormalities in the eyes. After 9 years, in addition to the color vision defect, there was gradual loss of visual acuity in both eyes, small central scotomas in the visual fields, elevation of the cone and rod thresholds in the dark adaptation, and decreased response in the photopic and scotopic electroretinogram. The diagnosis of a progressive cone-rod dystrophy was made. It is unusual for cone-rod dystrophy to begin with a distinct color vision defect only; the case report is presented.

Adolescent↗
PubMed1990

The experience of a university-based low vision clinic.

An open low vision clinic has been in operation at University of Wales College of Cardiff, Department of Optometry for 5 years. This paper describes the demography and visual characteristics of 218 consecutively presenting patients. A detailed survey of the aids prescribed is conducted. A significant proportion of low vision patients required only simple aids (56.8%) and low magnification (71.6%). It is suggested that these patients could be assisted in an optometric practice. In addition, visual acuity, distance or near is not a good indicator of eventual visual performance with an LVA. Therefore, it was concluded that all patients having measurable form vision should receive a low vision assessment.

Adolescent↗
PubMed1989

[The development of stereoscopic vision in the first months of life].

Dynamic random dot patterns generated on a TV screen by a special pattern generator are proven to be adequate stimuli for testing stereopsis. The registration of transient visual evoked cortical potentials (VECP) to these random dot stimuli offers objective proof of stereopsis. Using different disparities in older people a typical amplitude behaviour in the dynamic random dot stereo VECP with maximum amplitudes to medium sized disparities was found. Compared to 20 adults and 30 children with normal vision, in 26 children with negative TNO- and Titmus-tests for stereoscopic vision treated for strabismus no dynamic random dot stereo VECPs could be recorded. The development of stereoscopic vision in the first 12 months of life was investigated in five babies. First positive components in the dynamic random dot stereo VECP could be found in the 4th to 6th months of life in all children. From these results the assumption, that stereoscopic vision develops in later childhood, must be revised in favour of a much earlier period of infancy.

Adult↗
PubMed1989

[Recent trends and developments in the clinical study of color vision--the 2-comparison method].

Modern anomaloscopes with four independent light channels (i.e., the Besançon Anomalometer which was presented in 1980 at the DOG) allow accurate examinations of color vision. In our routine clinical examination, we use two metameric equations: the red-green Rayleigh equation and the blue-green Moreland equation. This two-equation method permits the diagnosis of congenital and acquired color vision defects in a precise quantitative way. In both equations the goal of the examination is to measure the absolute matching range. The diagnosis is abnormal color vision if the absolute matching range is shifted and/or enlarged in one or both of the two metameric equations. A computer-controlled clinical examination of color vision, which will make the procedure simpler and shorter for the patient, is presently being developed.

Adolescent↗
PubMed1988

A new perimetric color vision analyzer.

A new apparatus was developed for mapping the extrafoveal color vision, the perimetric color vision analyzer. A yellow test object with varying degrees of saturation is presented on a cathode ray tube color display in a random sequence at one of 10 points around the fixation spot. The background is a mosaic pattern consisting of gray spots of the same size and shape as the test object, with various luminances. Background patterns with or without a test object are presented alternately. The subject is instructed to press a key when he detects a yellow object in the background pattern. The luminance of the test object is in the same range as the background gray spots. Since the luminance of background spots is changed synchronously at random when the test object appears, the subject can detect the test object only by the difference in color saturation. The results show the color contrast sensitivity at every designated point in the central visual field. The clinical application of the perimetric color vision analyzer revealed extrafoveal color defects which could not be evaluated with conventional color vision tests. It also showed that in some chorioretinal and optic nerve disorders the topographic pattern of color contrast sensitivity disagrees with that of luminance contrast sensitivity measured with automated static perimetry.

Adult↗
PubMed1987

Blue-yellow vision deficits in patients with diabetes.

Home blood glucose monitoring has been introduced as a means to achieve good control in patients with diabetes mellitus. Many patients use color-reagent strips and color comparisons to determine blood glucose levels. Intact color vision in the blue-yellow range is necessary for accurately interpreting these strips.Blue-yellow vision deficits occur as a consequence of eye disease and are not genetic or sex-linked. We evaluated blue-yellow vision acuity in 70 diabetic patients and in 19 age-matched control subjects. The patients with diabetes were subdivided according to their degree of retinopathy as follows: no disease (N = 14), nonproliferative diabetic retinopathy (N = 16), proliferative diabetic retinopathy (N = 14) and postlaser-treated (N = 26). None of the control group had deficits. Each group of diabetic patients had a statistically significant increase in color vision deficits compared with the controls. In the laser-treated group, deficits occurred in most patients, were more severe and were significantly increased over all other diabetic subgroups. These deficits may impair visual interpretation of home blood glucose monitoring strips.

Aged↗
PubMed1986

Eye-movement-dependent loss in vision and its time course during vergence.

The attenuation of vision that has long been known to accompany saccadic eye movement has a significant component that is not attributable to visual masking or image smear, and this suppression of vision is now associated with nonsaccadic movement. The purpose of the present experiment was to determine the time course of visual suppression during a vergence eye movement. Suppression was evaluated psychophysically in human observers by measuring their loss of sensitivity to a brief, full-field decrement of light during 6 degrees-9 degrees convergence. Vergence-related suppression was similar in total duration and amplitude to saccadic and blink-related suppression. Since these other forms of oculomotor activity are vastly different in speed and total duration, it is unlikely that suppression results directly from the activity itself. Instead, these results support the hypothesis that a common, more centrally originating, suppression of vision occurs during eye movements, including saccades, eyeblinks, and vergence. Thus, while vision during eye movements can often be reduced through masking and smearing effects, the movement-dependent visual suppression measured in these experiments is a more generally occurring event.

Convergence, Ocular↗