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At least 1,639 records · Page 91Linked to original sources
PubMed2003

Assessment of colour vision as a screening test for sight threatening diabetic retinopathy before loss of vision.

AIM: To assess the effects of sight threatening diabetic retinopathy (STDR) on colour vision and to evaluate automated tritan contrast threshold (TCT) testing for STDR screening before significant visual loss. METHOD: Patients were recruited from a hospital based photographic screening clinic. All subjects underwent best corrected Snellen visual acuity (BCVA) and those with 20/30 vision or worse were excluded. Automated TCT was performed with a computer controlled, cathode ray tube based technique. The system produced a series of sinusoidal, standardised equiluminant chromatic gratings along a tritan confusion axis. Grading of diabetic retinopathy was made by one of the team of experienced ophthalmic registrars (SpR) using slit lamp biomicroscopy and a 78D lens; HbA(1c) and urine albumin were also tested. RESULTS: Patients with STDR had significantly worse TCT despite normal BCVA (p<0.0001). TCT yielded a sensitivity of 100% for detecting diabetic maculopathy and 94% for STDR with a specificity of 95%. Logistic regression analyses showed that TCT (p<0.001) and HbA(1c) (p<0.05) correlated significantly with the presence of STDR but duration of diabetes, urine albumin counts, and BCVA failed to show any significant correlation. No associations between TCT and duration of disease, TCT and HbA(1c), and TCT and urine albumin counts were found. CONCLUSION: Tritan colour vision deficiency was observed in patients with STDR despite their normal BCVA. These results indicate that automated TCT assessment is an effective and clinically viable technique for detecting STDR, particularly diabetic maculopathy, before visual loss.

Adolescent↗
PubMed1995

Hyperacuity test to evaluate vision through dense cataracts; research preliminary to a clinical study. I. Studies conducted at the University of California at Berkeley before travel to India.

BACKGROUND. Patients with dense ocular media disorders retain the ability to project or point to an intense source of light. Using this response capability and high luminance points of light as stimuli, Vernier judgments (a hyperacuity test) can be made by these patients, even without the presence of a "window" through a leucoma, cataract, or bleed. Without coaching, these individuals are able to locate the centers of the individual degraded point images if the individual light sources are adequately separated (i.e., if sufficient "gaps" exist between the individual stimuli), and they can spatially align the degraded images. Advanced cataracts are the main cause of blindness in the developing world, and this is a treatable condition. In these nations, only a modest proportion of affected patients receive surgery, and only 5% or less of these individuals obtain treatment in two eyes. There are incredibly large and rapidly growing backlogs of advanced cataract patients requiring care (many millions). Because of the 20 to 30% failure rates that occur after treatment (all causes) in many developing world settings, a test performed before surgery, which offers a meaningful estimate of postsurgical visual outcome, can be valuable. Using the principle defined above, we seek to determine before surgery those individuals who will derive most benefit from cataract removal, and which of two cataractous eyes has the better postsurgical visual prognosis. EXPERIMENTAL. In Berkeley, we performed a series of preliminary studies on a Vernier acuity test before initiating a clinical study in a developing world setting. These studies were conducted upon young adult normal subjects wearing their usual vision corrections, with and without induced refractive errors, and/or with or without simulated dense nuclear cataracts. We sought (1) to determine the number of repeat trials necessary for reliable outcomes; (2) to compare a two-point and a three-point Vernier acuity display; (3) to determine the shape of the measured response function at large gap separations between test points; (4) to define optimal test distance and stimulus size; (5) to assess the effect(s) of a broad range of uncorrected refractive errors upon outcomes; and (6) to consider means to minimize refraction-based errors by using a pinhole, a refractive correction, and/or selective spatial filtering. We compared responses obtained using the current CRT/VDT-based, computer-driven (Berkeley) instrument with a new precision optical/mechanical computer-driven (India) instrument. The India instrument is needed to determine design parameters for a next stage simpler, cheaper, more rugged field instrument(s).(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed2005

An abbreviated reading speed test.

PURPOSE: The Minnesota Low-Vision Reading Test (MNREAD) has been developed to measure reading speed. An abbreviated version of the MNREAD test was developed that presented only three large paragraphs and would be easier for children to complete. METHODS: Fifty children ages 8 to 18 years, with normal eye examinations or refractive error alone, underwent testing of reading speed using the MNREAD test. All the children read the standard MNREAD paragraphs starting at the 1.0 logarithm of the minimum angle of resolution (logMAR) level until they could no longer read the subsequent paragraph. Each eye was tested separately, using the second MNREAD card for the left eye. The standard MNREAD reading speed was calculated by plotting the speed for each paragraph, determining the critical print size, then taking the median value of all the paragraphs above the cutoff paragraph. The proposed abbreviated test reading speed was calculated from the median of three large paragraphs (logMAR, 1.0, 0.9, and 0.8). At a second site, 25 children with a variety of ocular conditions were similarly tested using an alternative abbreviated test (logMAR, 1.3, 1.2, and 1.1). The standard and abbreviated reading speeds were then compared between tests and between eyes using generalized estimating equation and intraclass correlation coefficients. RESULTS: The mean reading method speeds with the standard and abbreviated tests were almost identical [177 words per minute (wpm) +/- 46 wpm vs. 178 +/- 46 wpm, p = 0.43 for normal children and 140 +/- 29 wpm vs. 141 +/- 33 wpm, p = 0.35 in children with a variety of ocular conditions]. CONCLUSION.: The new abbreviated version of the MNREAD reading speed test yields similar results to the standard MNREAD test in children. The new abbreviated MNREAD test is faster to administer and appears to be particularly useful for children.

Adolescent↗
PubMed1993

Impact of new and emerging instrumentation in optometry.

Traditional tests of vision emphasize visual acuity, visual fields, and testing for hereditary color vision defects. New instrumentation for testing vision has proliferated due to advances in our knowledge of the visual system, the availability of new technologies, the introduction of computers into practice, and the expanded scope of optometric practice. Each is discussed in relation to the subsequent symposium papers by other authors.

Color Perception↗
PubMedDate not supplied

[Color vision in school children: evaluation of a new test]

OBJECTIVE: To compare standard color vision test results (Ishihara test) with a new test developed by the authors ("crayon" test) for the detection of congenital dyschromatopsia. METHODS: Cross-sectional study of 712 children from three public schools and one private school in the city of Porto Alegre, state of Rio Grande do Sul. Children with learning disabilities, or systemic and ocular diseases were excluded from this random sample. Two color vision tests, Ishihara test (short version with 14 plates) and crayon test (developed by the authors) were sequentially applied. Each test was applied by different evaluators and analyzed by a third evaluator. RESULTS: The crayon test showed a specificity of 100% (99.3-100%) and sensitivity of 38.5% (15.1-67.7%) when compared to Ishihara test. The prevalence of congenital dyschromatopsia in this population sample was 2.6% for male children, and 0.9% for female children. CONCLUSIONS: The crayon test results showed greater specificity than Ishihara test in the studied group; however, sensitivity was not adequate for a screening test. It is necessary to improve the sensitivity so that congenital dyschromatopsia can be detected by the crayon test.

Journal Article↗
PubMed2002

A test battery of child development for examining functional vision (ABCDEFV).

A battery of 22 tests is described, intended to give an integrated assessment of children's functional visual capacities between birth and four years of age. As well as sensory visual measures such as acuity, visual fields and stereopsis, the battery is intended to tap a range of perceptual, motor, spatial and cognitive aspects of visual function. Tests have been drawn from practice in ophthalmology and orthoptics, vision research, paediatric neurology, and developmental psychology to give an overall view of children's visual competences for guidance in diagnosis, further investigation, management and rehabilitation of children with developmental disorders. 'Core vision tests' require no motoric capacities beyond saccadic eye movements or linguistic skills and so assess basic visual capacities in children of any age. 'Additional tests' have age-specific requirements and are designed to pinpoint specific deficits in the perceptual, visuo-motor and spatio-cognitive domains. Normative data are reported on nine age groups between 0-6 weeks and 31-36 months, each including 32-43 typically developing children. Pass/fail criteria for each test are defined. These data allow the selection of a subset of tests for each age group which are passed by at least 85% of normally developing children, and so are appropriate for defining normal development. The normalized battery has been applied to a range of at-risk and clinical groups. Aspects of children's visual performance are discussed in relation to neurobiological models of visual development.

Child Development↗
PubMed1981

Testing for hypermetropia in the school vision screening programme.

The need and accuracy of a hypermetropia test, recommended as a screening test in Swedish schools, was evaluated in a series of 118 8-year-old children not wearing glasses. The distant visual acuity was determined without correction and with plus spheres of two different strengths, +1.5 D and +2.0 D respectively. When compared to the objective refraction and with an arbitrary limit of hypermetropia of +2.5 diopters, it could be shown that neither of the hypermetropia tests fulfilled the criteria of an adequate screening test. Except for two children all hypermetropics beyond +3.0 were previously known. The reading skills of the children were estimated by their teachers. No correlation was found between the degree of hypermetropia and reading difficulties. The results indicate that the hypermetropia test could be omitted from the regular vision tests of schoolchildren, at least in areas covered with an efficient pre-school vision screening.

Child↗