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PubMed2005

Aviation-relevent epidemiology of color vision deficiency.

INTRODUCTION: The Colour Vision Study Group of Transport Canada undertook a prevalence review to ascertain the degree and type of color vision deficiency (CVD) common in different populations. This was performed as a first step toward establishing whether a bone fide occupational requirement for color vision in aviation can be determined. LITERATURE SEARCH: Peer-reviewed articles with large populations and appropriate methodology for measuring CVD were assessed. Those pertaining to congenital CVD were cross-sectional prevalence studies with greater than 100 subjects assessed with a combination of pseudoisochromatic plates (PIPs) and Farnsworth D15 and/or an anomaloscope. Of 162 papers reviewed, 36 met these criteria for inclusion in the congenital CVD section. Acquired CVD papers were included based on the quality of color vision tests employed. CONGENITAL CVD: Data on congenital and acquired CVD are presented separately in parts 1 and 2. Part 1 demonstrates that although the prevalence numbers for North American and European populations are consistent with those reported in reference texts, congenital CVD is actually less prevalent in Asian, African, and Native populations. Therefore, the reported overall 8% prevalence of CVD in men applies only to Euro-Caucasians and is significantly lower in other racial groups. Possible evolutionary implications of dichromatism in humans are explored. ACQUIRED CVD: In this section the current understanding of acquired color vision deficiency, with an estimated prevalence ranging from 5 to 15% (51,95), is reviewed. Acquired CVD is frequently associated with significant impairment of visual acuity and/or visual field. However, many ocular diseases and drugs do primarily affect color vision, independent of other visual function, and one must remain vigilant to their presence. CONCLUSION: Congenital CVD is present in a consequential percentage of men, but considerable variability exists in different populations (2-8%). Acquired CVD may elude detection, but if severe is also associated with loss of visual acuity and/or visual field. Senescence remains the most common and increasingly prevalent cause for acquired CVD.

Animals↗
PubMed2005

[Development and evaluation of psychometric tests of the Chinese-version of low vision quality of life questionnaire].

OBJECTIVE: To develop and evaluate a Chinese language vision health related quality-of-life (VRQoL) questionnaire. METHODS: The low vision quality of life questionnaire (LVQOL) was translated and adapted into the Chinese-version low vision quality of life questionnaire (CLVQOL). The systematic protocols were set as 3 forward translations, 2 committee reviews and 1 back-ward translation. The CLVQOL was performed in 100 randomly selected people with low vision (primary group) and 100 people with normal vision (control group). Ninety-four participants from the primary group completed the CLVQOL and repeated 2 weeks later (test-retest group). The results were compared with patient demographics and the internal consistency reliability, test-retest reliability, item-internal consistency, item-discrimination validity, construct validity and discrimination validity of the CLVQOL were calculated. RESULTS: The review committee agreed that the CLVQOL replicated the meaning of the LVQOL and was sensitive to cultural adaptations. The Cronbach alpha coefficient and the split-half coefficient for the four scales and total CLVQOL scales were 0.75 to 0.97. The test-retest reliability as estimated by intraclass correlation coefficient was 0.69 to 0.95. Item-internal consistency was > 0.4 and item-discrimination validity was generally < 0.40. The varimax rotation factor analysis of the CLVQOL identified four principal factors. All of the scores of four subscales and the total score of CLVQOL of the primary group were lower than those of the control group, both in patients and local residents. CLVQOL scores were highly correlated with visual acuity. CONCLUSIONS: The CLVQOL is a culturally specific VRQOL measure instrument. CLVQOL can satisfy conventional psychometric criteria, can discriminate visually healthy populations from low vision patients and is valuable in the clinical practice and in the screening of the community populations.

Adult↗
PubMed1990

The relationship of retrobulbar hematomas to vision in cynomolgus monkeys.

An experimental model has been developed to measure the effect of retrobulbar hematomas on functional vision in cynomolgus monkeys. In this model, functional vision was quantitated using flashed evoked visual potentials in five monkeys following creation of retrobulbar hematomas. In one monkey used as a control, functional vision remained impaired for 180 minutes following induction of retinal ischemia by increased intraorbital pressure. In two monkeys in which increased intraorbital pressure was relieved by anterior chamber paracentesis following 15 minutes of retinal ischemia, flashed evoked visual potential promptly returned to baseline level. In two additional monkeys in which increased intraorbital pressure was relieved following 30 minutes of retinal ischemia, flashed evoked visual potentials improved but never returned to baseline levels. This study demonstrates the usefulness of flashed evoked visual potentials in measuring functional vision in cynomolgus monkeys. This experimental model should prove useful in evaluating the effects of increased intraorbital pressure on functional vision and the effect of intervention on impaired vision due to retrobulbar hematomas. Further studies with larger numbers of animals are needed to clarify these preliminary studies and document longer-term effects of retinal ischemia secondary to retrobulbar hematomas.

Animals↗
PubMed1990

Vision characteristics of individuals identified as Irlen Filter candidates.

Individuals with "scotopic sensitivity syndrome" have been reported to have visual symptoms including eye strain, headaches, blurred vision, double vision and words moving on the page. This study was designed to investigate Irlen's claims that these symptoms are unrelated to vision anomalies. She suggests that the use of Irlen tinted lenses/filters relieves these symptoms and results in improved reading performance. Thirty nine subjects (age 10-49) were recruited by advertising for a study of Irlen Filters/Lenses. Before the Irlen screening all subjects received an optometric examination. The results of this study demonstrate that 95 percent of the subjects identified as candidates for Irlen Filters did have significant and readily identifiable vision anomalies. Fifty seven percent of the subjects had received vision care within the past year, yet testing revealed that 90 percent of these subjects had significant vision problems that had not been corrected.

Accommodation, Ocular↗
PubMed1989

[Screening of early color vision loss in diabetic patients].

Colour vision defects have been claimed to appear in diabetes before any retinopathy is visible. In the present study diabetic patients and non diabetic control subjects were screened with two different colour vision tests which include both red-green and blue-yellow parts, and are suitable for quantitative analysis of scores. The Lanthony 40 Hue test and the Tokyo Medical College--T.M.C. tables were used to assess colour vision in 106 diabetic (50 insulin dependent and 56 non insulin dependent) patients and in 99 non diabetic control subjects. Diabetic patients without visible retinopathy, familiar colour vision defects and/or lens changes, had significantly higher scores than control subjects in both eyes. The differences were more evident in non insulin dependent patients. Statistical analysis showed that early loss of colour vision was correlated with age and duration of diabetes for older patients, while correlation with glycosylated hemoglobin was moderately positive only for younger patients. Both tests (especially the Lanthony 40 Hue) resulted to be highly specific and could be used for the clinical study of colour vision losses in diabetic patients.

Adult↗
PubMedDate not supplied

Color vision testing to assist in diagnosis of digoxin toxicity.

This report describes an initial step in the process of determining whether color vision changes might form the basis for testing to assist in diagnosis of digoxin toxicity. The research questions concerned the types of color vision deficiencies found in people with elevated digoxin levels, the types of color vision tests that could help identify color vision changes in these people, and the relationship between serum digoxin level and subjects' responses to color vision tests. Three groups of subjects with a minimum of one week on maintenance digoxin therapy were tested. Two groups who were free of selected known causes of abnormal color vision participated in a single test session: clinic women (N = 19) and hospitalized women (N = 30). A third group (N = 10) was initially tested at a time of elevated serum digoxin levels (greater than or equal to 2.5 ng/ml) and retested at therapeutic levels. The Farnsworth-Munsell 100-Hue Test was performed on the clinic women. All subjects were tested with the Ishihara; the Hardy, Rand, and Rittler (HRR) plates; and the Farnsworth Panel D-15. The 49 women who had a single test session demonstrated a positive relationship between digoxin level and failing the Ishihara (p less than .05). On retest at therapeutic levels, the group with initial high digoxin levels had a significant reduction in the number of Ishihara (p .005) and HRR (p less than .005) errors. The Panel D-15 lacked sensitivity. Most subjects with high digoxin levels would not have been able to perform a reliable 100-Hue test. Red-green deficiency was the most common defect.

Adult↗
PubMed1995

Vision impairment and corrective considerations of civil airmen.

BACKGROUND: Civil aviation is a major commercial and technological industry in the United States. The Federal Aviation Administration (FAA) is responsible for the regulation and promotion of aviation safety in the National Airspace System. To guide FAA policy changes and educational programs for aviation personnel about vision impairment and the use of corrective ophthalmic devices, the demographics of the civil airman population were reviewed. METHODS: Demographic data from 1971-1991 were extracted from FAA publications and databases. RESULTS: Approximately 48 percent of the civil airman population is equal to or older than 40 years of age (average age = 39.8 years). Many of these aviators are becoming presbyopic and will need corrective devices for near and intermediate vision. In fact, there has been approximately a 12 percent increase in the number of aviators with near vision restrictions during the past decade. Ophthalmic considerations for prescribing and dispensing eyewear for civil aviators are discussed. CONCLUSIONS: The correction of near and intermediate vision conditions for older pilots will be a major challenge for eye care practitioners in the next decade. Knowledge of the unique vision and environmental requirements of the civilian airman can assist clinicians in suggesting alternative vision corrective devices better suited for a particular aviation activity.

Adult↗
PubMed1995

Older Alabamians System of Information and Services (OASIS): a model Title VII chapter 2 low vision rehabilitation program.

BACKGROUND: Little attention has been paid in the ophthalmic literature to programmatic issues of low vision rehabilitation services delivery. The Older Alabamians System of Information and Services (Project OASIS) is a model low vision rehabilitation program functioning within the state of Alabama. This program is funded through Title VII, chapter 2 of the Rehabilitation Act, Independent Living Services for Older Blind Individuals. The program provides a comprehensive array of independent living services, including optometric low vision evaluation and low vision devices, to persons who are older and blind. Through intergency agreements between various state agencies and private entities, OASIS is able to maximize limited resources and reduce service redundancies. METHODS: Components of the OASIS consortium are reviewed along with outcomes of participants in fiscal year 1993-94. RESULTS: In fiscal year 1993-94 1,114 persons were entered into Project OASIS. Over half (569/1,114) of individuals accepted into the program received traditional optometric low vision rehabilitation services. More than 80% (586/717) of persons were able to achieve their independent living goals. CONCLUSIONS: Through a consortium effort between aging and rehabilitative services, minimal resources have been maximized to allow older visually impaired adults to benefit from comprehensive low vision rehabilitation services.

Activities of Daily Living↗
PubMedDate not supplied

Assisting low-vision patients in Japan.

1. Assisting low-vision patients in sitting down and in properly placing their heads for a slit-lamp examination is fundamental in low-vision patient care. 2. Ideally, chairs and other furniture in rooms used by low-vision should not be easily moved. Movable chairs are not stable, and thus could be dangerous, especially to people with low vision. Also, it is extremely important that objects are always placed at the same locations. 3. The staff should experience the difficulties encountered by low-vision patients by undergoing some of the same examinations that these patients undergo, and by walking while wearing some sort of vision reducer.

Humans↗
PubMed1995

Luminance and chromatic contrast effects on reading and object recognition in low vision: a review of the literature.

This paper reviews the literature on the effects of luminance and chromatic contrast on reading and object recognition in low vision. The general consensus is that whereas luminance contrast can enhance reading and object recognition for some low vision subjects, chromatic contrast does not aid low vision reading but may be useful in low vision object recognition. Although providing useful theoretical results, the experimental designs have so far been remote from the conditions that low vision patients may experience in the home and work environment. Suggestions are made for an 'ideal' experimental design and details of current research, using conditions more likely to be experienced by low vision subjects in everyday life, are given. This research makes use of a recently developed instrument, the Intuitive Colorimeter.

Cognition↗
PubMed1977

The future of vision screening.

The future of vision screening is presently receiving heated debate. Recent federal legislative activity in the area of comprehensive health planning has caused renewed interest in vision screening. Optometric recommendations supported at various governmental levels call for the development of standards for comprehensive vision screening of school children on a national scale. This paper attempts to review the philosophy and justification for school vision screening and to bring the readers up to date on related governmental activity. The question of adequate manpower to implement a nationwide vision screening program is discussed, and an argument is developed for preparing school nurse practitioners to assume an expanded role in comprehensive vision screening.

Adolescent↗
PubMed1977

A multidiscipline approach in low vision rehabilitation.

The first low vision clinic was instituted at the Industrial Home for the Blind in 1953 in response to a growing demand that more effective use be made of the residual vision in blind persons. The technology was there. Eye practitioners certainly knew enough about vision problems to offer many of these people an opportunity to enter a new life. The problem was: how to put that knowledge to work through a sound service delivery system. By its twentieth anniversary in 1973 the clinic had seen almost 5,000 patients for low vision evaluation and had built a service which consistently provided substantial and useful improvement in vision through the use of optical aids to a majority of its patients. The low vision optometric staff works as an integral part of a rehabilitation team. That team consists of a number of professionals, including ophthalmologists, social workers, teachers, and a variety of rehabilitation instructors. All members work simultaneously to create a total program of rehabilitation for thepartially sighted. We feel this teamwork approach is of basic importance to effective rehabilitation.

Adolescent↗
PubMed1997

Evaluation of mid-term stability of night vision tests.

BACKGROUND: Dark adaptation rate, scotopic retinal sensitivity and contrast sensitivity under mesopic conditions, but not visual acuity, have been shown to be directly related to the ability to identify military targets at night. These parameters can be used to select personnel for specific military tasks demanding excellent night vision, as well as to assess pharmacological effects on night vision. PURPOSE: To evaluate the mid-term (2 to 6-week period) stability of night vision tests based on assessment of the above parameters. METHODS: Dark adaptation rate, scotopic retinal sensitivity and contrast sensitivity under mesopic conditions were studied in 16 young volunteers during a 6-week period. RESULTS: Tests of scotopic retinal sensitivity (after 30 min of dark adaptation) exhibited high reproducibility and a low fluctuation rate, with a high correlation between values at week 0 and at 2-week intervals during the following 6 weeks of the study (rs (week 0 to week 6) = 0.81, p = 0.0001). The reproducibility of mesopic contrast sensitivity tests (average of 1.5, 3, 6 and 12 cycles per degree, (cpd)) was fair (rs (week 0 to week 2) = 0.67, p = 0.0045), whereas that of dark adaptation rate tests was poor. CONCLUSIONS: In view of the reproducibility characteristics of these night vision tests, assessment of night vision ability in pilots and military personnel, as well as assessment of pharmacological effects on night vision, may be based on scotopic retinal sensitivity (after 30 min of dark adaptation) and contrast sensitivity under mesopic conditions (average of 1.5, 3, 6 and 12 cpd).

Adult↗
PubMed1999

Crowding in central and eccentric vision: the effects of contour interaction and attention.

PURPOSE: To quantify the crowding effect with eccentric stimuli and to determine the relative contribution of neural interaction and attention to crowding in central and eccentric vision. METHODS: Monocular visual acuity was measured with computer-generated tumbling E and Landolt C targets presented centrally or at 2 degrees in the right visual field. Crowding distractors were designed to cause increasing contour interaction or increasing need for focused attention. A four-alternative forced-choice method of constant stimuli was used. In experiment 2 the distance between the target and the distractors was varied. RESULTS: Data are presented in terms of normalized visual acuity. Crowding in central vision was minimal, mainly caused by contour interaction, and did not occur with distractors more than four stroke widths distant. Crowding in eccentric vision was far greater in magnitude and extent (occurring for distractors as far as 16 stroke widths distant) and was caused by contour interaction and attentional factors. CONCLUSIONS: The results indicate that eccentric vision differs quantitatively and qualitatively from central vision. The extent of contour interaction effects are consistent with the proposed size of cortical processing zones. The results are discussed with reference to current theories of preattentive and attentive tasks and with reference to subjects with low vision due to central scotoma who use an eccentric retinal locus for fixation.

Adult↗
PubMed2026

Guidance (challenges and priorities) in the assessment of children with low vision: ERN-EYE clinical consensus statement.

Across Europe, children living with low vision often face inconsistent approaches to the assessment of their visual function, leading to delays in diagnosis and unequal access to care. To address this gap, a multidisciplinary group of experts from 8 European countries developed a clinical consensus statement (CCS), using a modified Delphi process. This CCS provides guidance on evaluation of primary visual functions in children with low vision, regardless of etiologies. Assessing visual function can be challenging and cannot be limited to testing visual acuity. It requires a comprehensive approach that takes into account the child's developmental age and necessary adjustments for vision loss. This consensus statement presents different validated tools to evaluate visual acuity, contrast sensitivity, visual field, and color vision. It provides practical guidance for their use across developmental stages, including infancy and in children with syndromic or neurodevelopmental conditions, and highlights the critical role of caregivers in ensuring reliable assessments. The recommendations emphasize the need for age-appropriate testing strategies, tailored adaptations for low vision and additional impairment, and the importance of early assessment to support timely habilitation and optimize developmental outcomes.

Assessment↗
PubMed1998

Baltimore Vision Screening Project. Phase 2.

BACKGROUND: Vision screening in preschool and school age children remains a valuable method of identifying potentially treatable visual abnormalities, as well as refractive errors in the school age population. A major difficulty in conducting these types of programs is the inconsistent follow-up encountered frequently in children identified by the screening program. The Baltimore Vision Screening Project was designed to address the issue of access to care for a group of inner city elementary school students by providing on-site evaluation and treatment. METHODS: A standard vision-screening protocol was administered to prekindergarten and kindergarten students attending an inner city elementary school and access to care provided at the school. Children identified by the screening were examined at the school, and appropriate treatment was prescribed. The second phase of the study details a return to the school 1 year after the initial screening. The purpose of this was to reassess the level of visual morbidity in this population and to evaluate the effects of providing treatment in the previous year. RESULTS: Two hundred eighty-five children were screened during the 1994-1995 school year. Visual morbidity statistics from the follow-up year were similar to those of the previous screening: 5.3% diagnosed with amblyopia, 3.2% with strabismus, and 7.4% with refractive errors. Forty of the 68 children identified, examined, and treated in the previous year still were attending the school during the follow-up investigation. Compliance with recommended treatment was 30% in this group, with only 20% of the students passing the vision screening the following year. CONCLUSIONS: The follow-up screening confirmed the presence of significant visual morbidity in this group of preschool and kindergarten students. Nearly two thirds of the students had not complied with the recommended treatment or spectacle wear or both, despite providing immediate access to this care through the vision-screening program.

Baltimore↗
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↗
PubMed1989

Psychophysics of reading. VIII. The Minnesota Low-Vision Reading Test.

This is the eighth in a series of papers dealing with the role of vision in reading. In previous papers, we have evaluated the effects of stimulus and subject variables on reading rate using a drifting-text procedure. In this paper, we describe a new test of reading rate that uses static text, called the Minnesota Low-Vision Reading Test (MNread). It is microcomputer-based, and more easily set up and administered than the drifting-text procedure. It is of potential value as a standardized psychophysical test of reading and should be useful in research, clinical, and educational applications. Some types of low-vision aids rely on drifting text and others on static text. Is reading performance different for these two modes of text presentation? We measured reading rate as a function of angular character size for normal and low-vision subjects with drifting and static text. Although reading rates were highly correlated for the two modes of text presentation, normal subjects usually read static text more rapidly. The reverse was true for low-vision subjects; their reading rates for drifting text were slightly higher (average 15%) than for static text.

Adult↗