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PubMedDate not supplied

The X-Chrom lens. On seeing red.

A broadband red filter placed over one eye will have the effect of improving the ability of certain color vision defectives to name colors correctly. A red-tinted contact lens will have the same effect; such a device is marketed under the name, the X-Chrom lens. In this article, the author examines the basic properties of color vision defects, explains the optical effect of the red filter, and reviews several studies which evaluate the effect of the X-Chrom lens. He concludes that while the lens may allow the wearer to achieve a better score on certain color vision tests, it does not actually correct color vision in the natural environment. Deleterious effects of wearing a red filter are also discussed. It is advised that patients wearing the X-Chrom lens be fully apprised of its limitations and of dangers that may be created by the associated visual distortions.

Color Perception Tests↗
PubMed1994

Variation in ophthalmic testing before cataract surgery. Results of a national survey of ophthalmologists.

Little information is available either for the clinical value of many ophthalmic tests performed preoperatively in the evaluation of patients for cataract surgery or for variation in ophthalmologists' use of such tests. To assess variation in ophthalmologists' use of ophthalmic tests, we conducted a national survey of American Academy of Ophthalmology members. Thirty-three percent, 17%, 37%, and 19% of the respondents reported that they "frequently" or "always" perform glare testing, contrast sensitivity testing, potential acuity measurement, and specular microscopy, respectively, in patients being considered for cataract surgery who have no history of eye disease other than cataract. In contrast, 27%, 54%, 24%, and 48% of respondents reported that they never perform each of these four tests in such patients. Two ophthalmologist characteristics--a surgical volume of greater than 200 cataract extractions per year and performance of surgery in an ambulatory surgical center or private office (as opposed to a hospital)--were independently associated with an increased probability of performing each of these four tests frequently or always. Ten percent or less of the respondents reported that they frequently or always perform electroretinography, visual evoked response testing, photography of fundus or anterior segment, B-scan ultrasonography, formal color vision testing, and formal visual field testing in such patients. Thus, there is considerable variation in ophthalmologists' use of glare testing, contrast sensitivity testing, potential acuity measurement, and specular microscopy. A small percentage of ophthalmologists may be overusing several other tests in the evaluation of patients being considered for cataract surgery.

Adult↗
PubMed1997

Accuracy of recall of the legal number plate testing distance by U.K. drivers.

A consecutive sample of 100 drivers attending practice for a routine eye examination were asked to specify the legal vision test distance for compliance with U.K. driving requirements. Also recorded were age, gender, vision uncorrected and acuity. The aim of the study was to investigate the accuracy of estimation by drivers and to determine whether there were any age or gender differences. The results show that 97% of the sample were unable to specify the distance printed in the Highway Code and that 41% underestimated the distance as below 60 feet. This figure is discussed in the context of better education of drivers and the potential role this could have in improving road safety.

Adolescent↗
PubMed2003

Hydrocephalus with visual deficits in a cat.

A 22-month-old male Japanese mongrel cat with a history of dysuria and recurrent generalised tonic-clonic seizure was examined by neuro-opthalmological testing and computed tomography (CT). Vision testing revealed narrowing of the visual field in the right eye, and complete visual deficits in the left eye. Pupillary reactions, and motor and sensory function in the eyelids and the eyes were normal. The cat was diagnosed as hydrocephalus by CT examination, because dilation of the right lateral ventricle, and compression of the right temporal and occipital cortices was shown. The etiology of the hydrocephalus was unclear. Although a unilateral lesion of the upper visual pathway was suspected, a complete homonymous hemianopsia was not shown.

Animals↗
PubMed2002

Risk factors for motor vehicle crashes in older women.

BACKGROUND: Motor vehicle crash and fatality rates are higher per mile driven for elderly drivers, with an exponential increase above age 75. Identifying elderly drivers who are at risk for automobile crashes may help direct interventions to reduce their high rate of injuries and deaths. METHODS: Subjects were 1416 women aged 65 to 84 enrolled in the Portland, Ore. site of the Study of Osteoporotic Fractures. Motor vehicle crash information for the years 1986-1995 for each participant was obtained from the Oregon State Department of Transportation. Items from questionnaires, interviews, and physical examinations were tested prospectively for associations with the occurrence of motor vehicle crashes. RESULTS: About one third of participants (415 of 1416) had a motor vehicle crash during a mean follow-up time of 5.7 years. After adjustment for age and weekly driving mileage, risk factors significantly associated with motor vehicle crashes were a fall in the previous year [hazard ratio (HR) 1.53, 95% confidence interval (CI) 1.26-1.86], a greater orthostatic systolic blood pressure drop (HR 1.11 per 12.5 mm Hg, 95% CI 1.01-1.22), and increased foot reaction time (HR 1.10 per 0.06 second, 95% CI 1.00-1.22). Other neuromuscular tests, functional status, medical diagnoses, vision tests, and cognitive tests did not predict motor vehicle crashes in this study population. CONCLUSIONS: This prospective study with extended follow-up of a large cohort of elderly women has identified crash risk factors that can be measured in the clinical setting. Further study is needed to determine if interventions aimed at these risk factors can decrease the risk of motor vehicle crashes.

Accidental Falls↗
PubMedDate not supplied

Repeatability indices for the Farnsworth D-15 test.

The repeatability of the D-15 color-vision test is considered to be excellent. However, this conclusion is based on a subject pool which contained a large percentage of color-normals. This type of sampling could bias the repeatability results because color-normals rarely fail the test. Furthermore, color-normals usually do not perform the D-15 in the clinical setting. To establish the repeatability of the D-15 for a relevant clinical population, we examined the D-15 results from two different sessions for 116 subjects who had a congenital red-green color-vision defect. The kappa coefficient for intersession agreement indicated that approximately 84% of the subjects obtained the same pass/fail results at both sessions. The type of defect was repeatable on approximately 80% of the subjects. Although the repeatability of the D-15 for color-defective subjects was good, it was lower than the near-perfect agreement reported previously. The coefficients of repeatability for the crossings show that if a person makes less than five crossings then the test should be administered again in order to ensure that the test result is repeatable.

Adult↗
PubMed1999

Assessment of contrast sensitivity in children aged 3 years 9 months - 6 years with normal vision, visual impairment due to ocular disease and strabismic amblyopia.

The contrast sensitivity function was assessed in children and adults with normal vision, visual impairment due to ocular disease, and strabismic amblyopia. The methods used were: the LH contrast vision test and the ability to detect raisins, puffed rice and white and black sugar strands against a white and black background. The aim of the study was to see whether any of the tests could be used in the detection of subnormal vision, and to compare the results between the different groups of patients. The following parameters of contrast sensitivity function (CSF) were measured with the LH-test: the maximum contrast sensitivity, the total area of CSF, and the area of 8 spatial frequency bands. Difficulty in detecting an object with low versus high contrast was measured with the sugar strands. Subjects with subnormal vision due to ocular disease and strabismic amblyopia had lower contrast sensitivity than subjects with normal vision measured as the total area of the CSF or the area of a specific frequency band. However, the maximum contrast sensitivity value that could be measured with the test was not significantly different between the groups. No subject had difficulties in the detection of raisins and puffed rice on a white and black background. Difficulties in detecting sugar strands on a white background were not seen in the normal children, but approximately 65% of the children with visual impairment had difficulties, as did approximately 25% of the children and adults with strabismus. Most of these subjects also had low visual acuity, but there was no correlation between the level of reduction of visual acuity and the difficulty in detecting sugar strands.

Adult↗
PubMed1990

Modified Allen pictures to assess amblyopia in young children.

To produce a test of visual acuity for young children that is more sensitive to amblyopia than current preschool vision tests, the authors surrounded four Allen pictures with "crowding" bars. This modified Allen test was evaluated by measuring acuity of amblyopic children (n = 28) and children (n = 10) and adults (n = 5) with normal eyes. Mean acuities of amblyopic eyes for the modified pictures was 0.8 octaves or nearly three logMar Snellen lines poorer than for the isolated pictures. For nonamblyopic and normal eyes modified picture acuity averaged 0.1 to 0.4 octaves poorer than isolated picture acuity. Average acuities of amblyopic eyes (n = 22) for the modified pictures agreed with line letter acuities. These results suggest that the modified picture test induces contour interaction similar to that of line letter tests, and thus, is a more sensitive test of amblyopia in the preschool child than isolated symbols.

Adolescent↗
PubMed2003

Neuropsychological sequelae of exposure to welding fumes in a group of occupationally exposed men.

This study compares the neuropsychological function, emotional status, visual function, and illness prevalence of 76 former and current chemical industry welders primarily involved in steel welding, and exposed to welding fumes for an average of 24.9 years with that of 42 unexposed, non-welder controls. Health and occupational history questionnaires were administered, as were the neuropsychological tests included in the World Health Organization Neurobehavioral Core Test Battery, Luria Motor Test, and selected tests from the WAIS-III, and WMS-III. Emotional status tests included the BSI, POMS, BAI, and BDI, and vision tests included the Snellen near visual acuity, Lanthony d-15 color vision, Vistech Contrast Sensitivity, and Schirmer strips. While welders and controls performed similarly on tests of verbal skills, verbal retention, and auditory span, welders performed worse than controls on tests of verbal learning, working memory, cognitive flexibility, visuomotor processing speed, and motor efficiency. Welders had poorer color vision and emotional status, and increased prevalence of illnesses and psychiatric symptoms. The increased symptoms in welders were related to decreased scores on tasks measuring verbal learning, visuomotor abilities, visuospatial abilities, and information processing, and motor efficiency. Within the group of welders, the number of hours welding was negatively related to scores on verbal learning, auditory span, working memory, cognitive flexibility, and motor efficiency.

Adult↗
PubMed1991

Visual dysfunction in Alzheimer's disease: relation to normal aging.

In patients with Alzheimer's disease (AD), compared with age-matched and young healthy control subjects, visual deficits in the following functions were observed: color, stereoacuity, contrast sensitivity, and backward masking (homogeneous and pattern). Critical flicker fusion thresholds were normal, relative to age-matched healthy subjects. For color, the majority of the errors were tritanomalous (blue axis). Color and stereoacuity deficits were unrelated to severity of dementia, in accordance with models of vision that describe these functions as modular rather than diffuse for cortical localization. Although contrast sensitivity was depressed throughout the frequency range in AD, more patients were impaired at low than at high spatial frequencies, contrasting with the observed normal aging pattern of high-frequency loss. Healthy elderly subjects showed depressed critical flicker fusion thresholds and reduced contrast sensitivity at high frequencies, relative to the young group; differences between these groups were not found for the other vision tests. A subset of the AD group received detailed neuro-ophthalmological examination, and no abnormalities were found. This finding, taken together with normal thresholds for critical flicker fusion, suggests that the widespread visual dysfunction reported here is more likely to be related to known pathological changes in primary visual and association cortex in AD than to changes in the retina or optic nerve.

Adolescent↗
PubMed2004

Low contrast vision function predicts subsequent acuity loss in an aged population: the SKI study.

Can vision tests predict subsequent loss of acuity? The association between performance on several low contrast spatial vision measures, glare recovery, color discrimination, flicker sensitivity, stereopsis and ocular disease status at baseline and acuity loss 4.4 years later was examined in a large aged random sample with good initial acuity. In univariate analyses, several vision measures, retinal disease status and age were each significant predictors of subsequent acuity loss. In a multiple regression analysis, only low contrast spatial vision was a significant predictor, but the other vision measures, retinal disease status and age were not. For each doubling of low contrast spatial vision threshold at baseline, individuals were more than two times as likely to suffer subsequent significant visual acuity loss. Tests of low contrast spatial vision are strong predictors of significant subsequent visual acuity loss. These findings have implications for clinical trials, clinical management, and acceptance of these measures into clinical practice.

Aged↗
PubMed2001

Functional MRI as a tool to assess vision in dogs: the optimal anesthetic.

Functional magnetic resonance imaging (fMRI) is a recent advance in neuroimaging that provides a picture of brain activity with excellent spatial resolution. Current methods used to evaluate canine vision are poorly standardized and vulnerable to bias. Functional MRI may represent a valuable method of testing vision in dogs if the impacts of anesthesia on fMRI are understood. Six dogs were scanned during visual stimulation, each under three different anesthetic protocols (isoflurane, propofol, fentanyl/midazolam) to address the questions: (1) Can visually evoked fMR signals be reliably recorded in anesthetized dogs? and (2) Which anesthetic agent permits the least suppression of visually induced fMR signal in dogs? This study confirms that visual stimuli reliably elicit neural activity and fMR signal change in anesthetized dogs. No significant differences in images acquired under the three anesthetics were found, and there was no significant relationship between anesthetic dose and brain activity, within the range of doses used in this study. Images obtained during isoflurane anesthesia were more consistent between dogs than those obtained with the other two agents. This reduced variation may reflect the fact that inhalant anesthesia is more easily controlled than intravenous anesthesia under conditions associated with high field fMRI.

Anesthesia↗
PubMed1989

[Comparison of the Kolling distance vision stereo-test with current stereo-test procedures].

A new type of stereotest for distant vision (after Kolling) is compared with established stereotests for distant (different types of Zeiss Polatest) and near vision (Titmus, TNO, Lang tests) in a total of 203 patients. The Kolling test is based on the three-rod method in accordance with Helmholtz. The apparatus does not require separation of the visual input of the two eyes. This new stereotest is practice-oriented, quick, easy to understand and gives reliable and reproducible results. The test cannot be completed successfully with monocular viewing, if the head is fixed. The results show a good correspondence between the Kolling test and the Zeiss Polatest using disparate outlined figures. The Zeiss Polatest using random-dot patterns turned out to have the strictest criteria for this purpose of all stereotests. Interestingly enough, subjects performed much better in stereotests for near vision (Titmus, TNO tests) than in those for distant vision (Kolling test, different types of Zeiss Polatest). The widespread use of stereotests of near vision in driving tests is therefore problematic.

Adolescent↗
PubMed1988

Comparison of associated heterophoria measurements using the Mallett test for near vision and the Sheedy Disparometer.

The Mallett test for near vision and the Sheedy Disparometer are compared in terms of their ability to measure associated heterophoria. Twenty-two asymptomatic subjects were used. With the Disparometer, ten of these subjects, familiar with making prism vergence measurements, exhibited stable forced vergence fixation disparity curves, and the associated heterophoria values using both instruments were not significantly different. However, the twelve subjects not familiar with making such measurements generated fluctuating, unstable fixation disparity curves, and the associated heterophoria values were significantly different. Repeated trials with the randomly selected naïve subjects led to flatter, more stable fixation disparity curves and lower values for the x- and y-intercepts when using the Disparometer. The Mallett test, however, produced identical values for associated heterophoria in each successive trial. Therefore, the validity of measurements using the Disparometer in a clinical setting is questioned.

Adolescent↗
PubMed1985

Color vision deficiencies in two cases of digoxin toxicity.

Color vision deficiencies are a common sign of digoxin intoxication and color vision testing can be used to diagnose digoxin toxicity. We tested two patients, a 79-year-old man and a 61-year-old man, with digoxin toxicity by means of the Farnsworth-Munsell 100-hue test, AOH-R-R plates, and Ishihara plates. Initial testing disclosed both red-green and blue-yellow color vision deficiencies. These improved when digoxin levels diminished. The deficiencies were superimposed on preexisting acquired and congenital deficits. As serum digoxin levels decreased, the color vision deficiencies lessened on all three tests. The Farnsworth-Munsell 100-hue test gave the best quantifiable measure of color vision deficiencies, but proved difficult to use for routine bedside testing.

Aged↗
PubMed1982

A new assessment of the normal ranges of the Farnsworth-Munsell 100-hue test scores.

We gave the Farnsworth-Munsell 100-hue color vision test to 232 normal subjects between 10 and 80 years of age. One half the subjects underwent binocular testing followed by monocular testing. In the other half monocular testing preceded binocular testing. Performance was better with both eyes than with either eye alone. The worst performance occurred on monocular tests in subjects without previous experience with the task (that is, those for whom this was the first test). The well-known age trend was apparent (children and elderly have the worst color vision). New data are provided for judging the point at which the total error score may be considered pathologic.

Adolescent↗
PubMed1977

Ocular function in cirrhosis of the liver.

The ocular state of 28 ascertained non-alcoholic females with cirrhosis of the liver was assessed. Only twenty were able to go through the complete colour vision test, and among these, three patients (one without, and two with increased level of serum bilirubin) with acquired colour vision defects were observed. Visual acuity, visual field, intraocular pressure, binocular function, slit lamp microscopy, ophthalmoscopy and tear production were normal in all cases. It is concluded that the frequency of colour vision defects in the present sample is increased, and that alcohol abuse is not a prerequisite for colour vision defects in patients with cirrhosis.

Adolescent↗