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At least 991 records · Page 55Linked to original sources
PubMed1997

Screening for depression in older persons with low vision. Somatic eye symptoms and the Geriatric Depression Scale.

The authors compared the sensitivity and specificity of a somatic eye symptoms question with the Geriatric Depression Scale (GDS) to detect depression in older patients with low vision. The sample was 70 patients (65+ years) attending a low-vision clinic. A geriatric nurse-practitioner examined all patients, diagnosed major depression by DSM-III-R criteria, and completed the GDS and an eye symptoms (ES) questionnaire. Twenty-seven patients (38.6%) met criteria for major depression. Although the sensitivity of the ES and GDS were identical (63%), the GDS was more specific (77% vs. 54%) and had higher positive predictive value (63% vs. 46%). Both measures identified patients who were more functionally disabled than patients without ES or depression, but with similar vision. Depression frequently accompanies visual impairment in this population. Inquiring about ES appears to be less specific than the GDS, although neither method is highly sensitive. However these screening tools identify distressed persons whose disability is high relative to the severity of their vision loss.

Aged↗
PubMed2001

Intervention study on acquired color vision deficiencies in styrene-exposed workers.

The main aim of the study was to examine the possible effects of occupational exposure to styrene on color vision function and the course after reduction of exposure. Color vision function was examined in 22 styrene-exposed laminators and 11 control subjects at a boat manufacturing plant. The Lanthony D-15 desaturated panel was used to test acquired dyschromatopsia. In all, six examinations were performed: Monday morning and Thursday afternoon of the same week, before and immediately after a vacation of 4 weeks (altogether, phase 1), and approximately 10 months later (phase 2), after the exposure level of styrene had been reduced. Styrene uptake was objectified by biological monitoring measuring the metabolites mandelic acid and phenylglyoxcylic acid in urine samples taken on Thursday afternoon. In both Thursday examinations, styrene-exposed workers had higher color confusion index (CCI) values compared with controls, which indicated quantitative color vision loss. After an exposure-free period of 4 weeks, a significant decrease of CCI values to normal range was found in laminators. Reexamination 10 months later showed also lower CCI values in exposed workers, indicating a dose-effect relationship. Abnormal CCI values occurred primarily in subjects with an excretion of approximately 500 to 600 mg mandelic acid plus phenylglyoxcylic acid per gram creatinine or more. We concluded that styrene-induced color vision dysfunction is reversible after an exposure-free interval of 4 weeks. The current Biological Tolerance Value of 600 mg mandelic acid plus phenylglyoxcylic acid per gram creatinine, as used in Germany, protects styrene-exposed workers from this subclinical effect.

Adult↗
PubMed2001

Charles Bonnet syndrome in glaucoma patients with low vision.

PURPOSE: To characterize the nature and frequency of Charles Bonnet syndrome in glaucoma patients with low vision. PATIENTS AND METHODS: All patients attending the glaucoma clinic during a period of 10 months who had visual acuity of 20/80 or less in both eyes were included in this study. Each patient was questioned about the occurrence of visual hallucinations. Those who responded positively had a thorough interview relating to the characteristics of the hallucinations. Medical history and social history were taken, followed by a complete ocular examination. RESULTS: Eighty-nine patients met the inclusion criteria. Eleven patients (12.3%), eight men and three women, admitted to having experienced visual hallucinations. Except for one case, the patients did not disclose this experience previously. Eight patients had one repeatable hallucination, and three patients experienced more than one sight. The visions were usually sharp, and the figures were occasionally incomplete. Most hallucinations were chromatic. Frequency of hallucinations varied between daily and weekly, and duration was mostly a few minutes. In addition to glaucoma, nine of the eleven patients had other ocular findings that could have contributed to the reduction of vision. CONCLUSION: Visual hallucinations are not rare in glaucoma patients with low vision. Patients tend to conceal their experience of visual hallucinations, but a discussion of these phenomena with the patient and assurance of their harmless nature will reduce his or her anxiety and concerns.

Aged↗
PubMed1979

Binocular single vision and perceptual processing.

Stimuli with small binocular disparities are seen as single, despite their differing visual directions for the two eyes. Such stimuli also yield stereopsis, but stereopsis and single vision can be dissociated. The occurrence of binocular single vision depends not only on the disparities of individual stimulus elements, but also on the geometrical relation of different parts of the pattern presented to each eye. A pair of vertical bars with opposite binocular disparities is seen as single if the pair is moderately widely spaced but not if it is narrow. Vertical alignment and identity in length of such bars also increase the occurrence of double vision. It is argued that these effects reflect the extraction of features of the monocular patterns, with these detected monocular features determining the binocular percept. Single and double vision of bars differing in orientation can be similarly analysed. The occurrence of relatively elaborate processing of monocular signals does not exclude the possibility that binocular interaction can occur between signals that have not been so processed. Multiple sites or types of binocular interaction are likely.

Functional Laterality↗
PubMed1984

Variations of colour vision in a New World primate can be explained by polymorphism of retinal photopigments.

The squirrel monkey (Saimiri sciureus) exhibits a polymorphism of colour vision: some animals are dichromatic, some trichromatic, and within each of these classes there are subtypes that resemble the protan and deutan variants of human colour vision. For each of ten individual monkeys we have obtained (i) behavioural measurements of colour vision and (ii) microspectrophotometric measurements of retinal photopigments. The behavioural tests, carried out in Santa Barbara, included wavelength discrimination, Rayleigh matches, and increment sensitivity at 540 and 640 nm. The microspectrophotometric measurements were made in London, using samples of fresh retinal tissue and a modified Liebman microspectrophotometer: the absorbance spectra for single retinal cells were obtained by passing a monochromatic measuring beam through the outer segments of individual rods and cones. The two types of data, behavioural and microspectrophotometric, were obtained independently and were handed to a third party before being interchanged between experimenters. From all ten animals, a rod pigment was recorded with lambda max (wavelength of peak absorbance) close to 500 nm. In several animals, receptors were found that contained a short-wave pigment (mean lambda max = 433.5 nm): these violet-sensitive receptors were rare, as in man and other primate species. In the middle- to long-wave part of the spectrum, there appear to be at least three possible Saimiri photopigments (with lambda max values at about 537,550 and 565 nm) and individual animals draw either one or two pigments from this set, giving dichromatic or trichromatic colour vision. Thus, those animals that behaviourally resembled human protanopes exhibited only one pigment in the red-green range, with lambda max = 537 nm; other behaviourally dichromatic animals had single pigments lying at longer wavelengths and these were the animals that behaviourally had higher sensitivity to long wavelengths. Four of the monkeys were behaviourally judged to be trichromatic. None of the latter animals exhibited the two widely separated pigments (close to 535 and 567 nm) that are found in the middle- and long-wave cones of macaque monkeys.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

Parvocellular neurons limit motion acuity in human peripheral vision.

It is generally believed that the perception of moving targets is mediated by the magnocellular (M) pathway in primate vision, but evidence is emerging that the parvocellular (P) pathway may also play a role in motion perception. Human peripheral vision is susceptible to anomalous motion perception because of spatial aliasing, and in this study we used this fact to determine if the P pathway can mediate information about low- and high-velocity stimuli. Psychometric functions relating visual performance to stimulus spatial frequency were measured for the directional discrimination of drifting sinusoidal gratings presented at 40 degrees eccentricity. Applying the sampling theorem to our results, we estimated that the Nyquist frequency of the limiting sampling array for directional discrimination is 1.7 cycles per degree. This result was compared with the Nyquist limit and spatial filtering properties of M and P ganglion cells in the human peripheral retina, calculated from histological data on their density and dendritic field size. Our results provide evidence to suggest that the reversed motion illusion in human peripheral vision is due to spatial aliasing by the P ganglion cell mosaic. We conclude that the sampling density of P ganglion cells limits veridical motion acuity in human peripheral vision, even for high-velocity targets. This provides further evidence that the P pathway is involved in processing information about motion.

Discrimination, Psychological↗
PubMed1986

Ten years' experience in low vision practice.

The Low Vision Clinic at the Palmerston North Hospital has now been operating for 10 years. Over the course of these ten years a number of factors have emerged which can be as readily applied to general ophthalmological practice as to low vision practice. The philosophy of low vision care is one of which all ophthalmologists should be aware and includes factors to be taken into account when dealing with children, people in the workplace, and everyday factors involved in daily living activities, all of which are equally relevant in routine ophthalmological practice. This paper endeavours to share some thoughts on these factors and also discusses means by which the visually handicapped can be helped in areas where specialist low vision services are not readily available.

Humans↗
PubMed1998

Impact of vision impairment on functioning.

PURPOSE: The aim of the present study was to determine the impact of vision loss on the activities of adults. METHODS: Focus groups were conducted that were either disease specific, such as for people with age-related macular degeneration, diabetic retinopathy, glaucoma or those with congenital vision impairment, or according to previous involvement in rehabilitation services. Discussions were recorded and transcribed. Because many people were retired, leisure activities and personal independence were paramount. RESULTS/CONCLUSIONS: Younger people were concerned with gaining or continuing in employment or with educational opportunities. The age at onset of vision loss and the cause and duration of vision loss influence its impact. There appears to be a greater level of handicap in people with comorbid eye disease and related disease, such as diabetes.

Activities of Daily Living↗
PubMed2003

Repeatability of the C-100 colour vision test.

BACKGROUND: The C-100 colour vision test has been shown to have a high validity for diagnosing the type of red-green colour vision defect, however, there is little information on the repeatability of the test. This study examines the repeatability of the C-100 in classifying the colour vision defect as either protan or deutan. METHODS: The C-100 was administered on two occasions to 58 subjects with congenital red-green colour vision defects. The sessions were separated by a minimum period of 10 days. RESULTS: The repeatability of the C-100 was high with a kappa coefficient of agreement for diagnosis of 0.96. The few discrepancies were misclassifying protans as deutans. CONCLUSION: The C-100 is a highly repeatable test in terms of separating protans from deutans. However, if a discrepancy occurs, it is more likely to be a protan misclassified as a deutan rather than vice versa.

Adult↗
PubMed2004

Spectacle use and reduced unaided vision in third grade students: a comparative study in different educational settings.

BACKGROUND: The development of myopia is influenced by hereditary factors, environmental factors and gene-environment interaction. Reading and near-work activity are associated with myopia and myopic progression. This study sought to determine and compare the prevalence of reduced unaided vision and spectacle use among third grade Israeli students from three different educational settings. METHOD: A sample of 917 students (mean age 8.5 years, range seven to 10 years) was drawn from the three Israeli educational streams: secular, Orthodox and ultra-Orthodox. Children in the ultra-Orthodox education pathway begin studying at the age of three years and their daily reading involves sustained near work with increased accommodative effort accompanied by head-rocking movements. Reduced distance vision was used to indicate the likely development of or an increase in the amount of myopia. Spectacle lenses were measured to determine the prevalence of myopia. RESULTS: Of the 917 students studied, 103 (11.2 per cent) wore spectacles (14.2 per cent of the males and eight per cent of the females); 82.5 per cent of those who wore spectacles were myopic. Males from ultra-Orthodox schools had the highest rate of reduced unaided vision (72.5 per cent) compared with males from secular schools (27.3 per cent), males from Orthodox schools (59.3 per cent) or with females from all three groups (average of 34.8 per cent, p < 0.0001, chi squared). Males had a higher rate of reduced unaided vision, especially in the Orthodox and ultra-Orthodox schools. CONCLUSIONS: Our study suggests that Jewish ultra-Orthodox males have a higher prevalence and degree of myopia. The study habits of young children, including exposure to prolonged near tasks, high accommodative demands and possibly optical defocus induced by body sway, may contribute to the development of myopia.

Accommodation, Ocular↗
PubMed2004

The handicap of abnormal colour vision.

All people with abnormal colour vision, except for a few mildly affected deuteranomals, report that they experience problems with colour in everyday life and at work. Contemporary society presents them with increasing problems because colour is now so widely used in printed materials and in computer displays. Equal opportunity law gives them protection against unfair discrimination in employment, so a decision to exclude a person from employment on the grounds of abnormal colour vision must now be well supported by good evidence and sound argument. This paper reviews the investigations that have contributed to understanding the nature and consequences of the problems they have. All those with abnormal colour vision are at a disadvantage with comparative colour tasks that involve precise matching of colours or discrimination of fine colour differences either because of their loss of colour discrimination or anomalous perception of metamers. The majority have problems when colour is used to code information, in man-made colour codes and in naturally occurring colour codes that signal ripeness of fruit, freshness of meat or illness. They can be denied the benefit of colour to mark out objects and organise complex visual displays. They may be unreliable when a colour name is used as an identifier. They are slower and less successful in search when colour is an attribute of the target object or is used to organise the visual display. Because those with the more severe forms of abnormal colour vision perceive a very limited gamut of colours, they are at a disadvantage in the pursuit and appreciation of those forms of art that use colour.

Color Vision Defects↗
PubMed2005

The effect of abnormal colour vision on the ability to identify and outline coloured clinical signs and to count stained bacilli in sputum.

AIM: To determine if medical practitioners with congenital colour vision deficiencies (CCVD) are less able to identify and delineate the extent of coloured abnormal signs than those with normal colour vision. METHOD: Twenty-two medical practitioners with CCVD and 17 with normal colour vision, matched for age and gender, were shown 10 photographs. They were asked to identify and outline the extent of the clinical sign in eight that were of vomit or stool (six of these showing fresh blood), one of a skin rash and for one to mark the position of bacilli in sputum stained by the Ziehl-Neelsen method. RESULTS: There were statistically significant differences between the CCVD practitioners and those with normal colour vision in their ability to outline abnormalities in five of the six photographs that showed fresh blood, in the photograph of a rash and in marking the position of bacilli in the photograph of a stained slide. CONCLUSION: Medical practitioners with CCVD are handicapped in their evaluation of the presence and extent of coloured clinical signs. Medical schools should ensure that students with CCVD are aware of their deficiency and know its severity, so they can take special care in clinical practice.

Bacillus↗
PubMed1997

Routine ultrasound screening in pregnancy and the children's subsequent growth, vision and hearing.

OBJECTIVE: To test a hypothesis of no association between ultrasound exposure in early fetal life and growth or impaired vision or hearing during childhood. DESIGN: Follow up of eight to nine year old children born to women who participated in a randomised controlled trial on ultrasound screening during pregnancy. SETTING: Nineteen antenatal care clinics run by three central hospitals in Sweden from 1985 to 1987. POPULATION AND METHODS: Of 4637 eligible singleton pregnancies, 3265 (71%) were followed up through a questionnaire sent to their mothers. Analyses were performed both according to randomised groups and to ultrasound exposure. MAIN OUTCOME MEASURES: Parents' report of vision and hearing tests as recorded on child's record card. Parents' report of their child's weight and height at 1, 4 and 7 years of age. RESULTS: Reduced hearing was reported by 3.4% in the screening group compared with 3.5% in the nonscreening group (odds ratio [OR] 1.0; 95% confidence interval [CI] 0.67-1.41). The same prevalences were found when analysed according to ultrasound exposure (OR 1.0; 95% CI 0.67-1.42). Reduced vision was reported by 6.3% in the screening group compared with 7.8% in the nonscreening group (OR 0.8; 95% CI 0.60-1.03). Corresponding figures for ultrasound exposed and unexposed were 6.2% and 8.0%, respectively (OR 0.8; 95% CI 0.58-1.00). No statistically significant differences in body weight or height at 1, 4 or 7 years of age between screened and not screened children or between exposed and unexposed were found. CONCLUSION: This study found no association between ultrasound exposure in early fetal life and growth or impaired vision or hearing during childhood.

Adult↗
PubMed2004

Low vision service delivery: an audit of newly developed outreach clinics in Northern Ireland.

Recent publications recommend that low vision services are multi-professional; easily accessible; freely available to all those with visual impairment; monitored by professional and patient groups, and responsive to user feedback. These standards were applied when developing low vision outreach services in Northern Ireland in 1999/2000. Results are reported of the complete clinical audit cycle, coupled with a patient satisfaction telephone questionnaire, which was used to evaluate the service. Of the 48 patients randomly selected from the list of clinic attendees, 28 (58%) were female, 27 (56%) over 80 years of age and 38 (78%) had a primary ocular diagnosis of age related macular degeneration (AMD). Of the 46 low vision aids issued at patients' first appointments, 30 (67%) were illuminated stand magnifiers and 29 (63%) had magnification levels of x5 or less. A total of 46 (96%) patients reported that they had benefited from low vision services.

Aged↗
PubMed2005

Impaired vision and the ability to take medications.

OBJECTIVES: To assess relationships between vision (contrast sensitivity, stereopsis, visual acuity) and a performance-based measure of ability to implement new medications. DESIGN: Cross-sectional analysis; prospective cohort study. SETTING: Community-based. PARTICIPANTS: Three hundred thirty-five participants aged 73 to 82 in Year 3 of the Women's Health and Aging Study II, a representative sample of the two-thirds least-disabled community-dwelling women. MEASUREMENTS: Hopkins Medication Schedule Pillbox Ratio, a joint measure of accuracy and time, and a performance-based measure of ability to implement a prescription. Participants received written and verbal instructions for taking two medications and were directed to place pills in a pillbox accordingly. Vision assessments: contrast sensitivity (Pelli-Robson letter sensitivity chart), stereopsis (Randot Circles), and visual acuity (Early Treatment Diabetic Retinopathy Study eye chart). RESULTS: Forty-four percent (148/335) of women incorrectly placed one or both medications. Each vision measure was positively associated with Pillbox Ratio scores and varied with cognition and time to completion. Better visual acuity, contrast sensitivity, and stereopsis were each associated with better performance in women with poor cognition who filled the pillbox quickly. Additionally, better visual acuity was associated with better performance in participants with good cognition who filled the pillbox slowly; better stereopsis was associated with better performance in participants with poor cognition who filled the pillbox slowly and whose stereoacuity was below normal. CONCLUSION: Visual acuity, contrast sensitivity, and stereopsis should be considered potential risk factors for impaired ability to implement a medication regimen in older adults. Future research should investigate the role of vision, including contrast sensitivity and stereopsis, on performance of other instrumental activities of daily living.

Aged↗
PubMed1997

The impact of cataract surgery on low vision patients. A population based study.

PURPOSE: To assess the impact of cataract surgery on low vision patients. METHODS: Self-estimated ability to perform visually demanding tasks before and after cataract surgery and expectations and satisfaction with the surgery were analysed in all low-vision patients (n = 52), who during a one-year period underwent surgery at Norrlands University Hospital in Umeå, Sweden. Self-administered questionnaires were used and the records of the patients were studied. RESULTS: The majority (81%) of the low vision patients reported an improved ability to perform visually demanding tasks after surgery. The number of patients who were unable to read newspaper-size print decreased significantly, from 44% to 21% after surgery. The subjectively improved visual ability as well as the augmentation of VA of the operated eye were both significantly related to satisfaction with the outcome of surgery. CONCLUSION: Most low-vision patients with significant cataract benefit from surgery, both subjectively by increased ability to perform visually demanding tasks as well as by an improved visual acuity. Particularly patients with loss of peripheral visual fields subjectively gain in orientation ability. It is important to reduce unreasonable expectations about the outcome of the surgery.

Activities of Daily Living↗
PubMed2001

Vision, visual needs, and quality of life of older people in rural environments: a report and synthesis of a meeting.

Vision as an aspect of rural aging was a major portion of the First International Conference on Rural Aging. Various perspectives on the relationship of vision to rural aging were presented in two symposia, two paper sessions, one workshop and the poster session (a total of 28 presentations). In summarizing this rich and varied material, the author emphasizes that: (a) vision is important to maintaining a healthy, active life as one ages; (b) impaired vision is generally preventable or treatable; (c) well-designed community programs can assist in prevention and treatment; and (d) assessing the effects of these programs requires evaluation of patients' quality of life. More research is needed to refine strategies for creating, maintaining and evaluating community-based eye care programs and integrating them with existing public health or other community programs.

Aged↗
PubMed2004

Nonmetro residence and impaired vision among elderly Americans.

PURPOSE: Nonmetro and metro elderly people are contrasted in their risk of having (relative to lacking) an impairment in distance vision and in near vision. METHODS: Using the 1995-1996 panel (Wave 2) of the Asset and Health Dynamics Among the Oldest Old (AHEAD) Survey, the prevalence of 5 eye-threatening conditions (cardiovascular disease, cataract, diabetes, glaucoma, and hypertension), a variety of medical treatments for these conditions, the number of talks/visits with doctors in the 2 years before Wave 2, and several relevant demographic characteristics of the 6,817 respondents were controlled. FINDINGS: Nonmetro and metro elders have the same risk of impairment in distance vision. After controlling for other factors, nonmetro elders have a higher risk than their metro peers of an uncorrected impairment in near vision (probably presbyopia). CONCLUSIONS: Nonmetro elders may confront more impediments to updating their corrective lenses for presbyopia. Implications for public health policy are discussed.

Aged↗