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At least 1,225 records · Page 68Linked to original sources
PubMed2002

Fixation disparity: binocular vergence accuracy for a visual display at different positions relative to the eyes.

Some observers do not fixate accurately at the point of regard: Their vergence angle (between the visual axes of the two eyes) may correspond to points slightly nearer or farther away. This vergence error, or fixation disparity, was measured with nonius (vernier) lines at six positions of a visual display relative to the eyes. At viewing distances of 40, 60, and 100 cm, the display was located either at eye level or at a downward inclination of gaze direction of -25 degrees relative to horizontal. Viewing conditions resembled typical office work. Lowering the screen induced a near shift in mean vergence response of 0.6 min arc, irrespective of viewing distance; the closer the screen, the more distant was the vergence response relative to the target (by 2.5 min arc on average). The slope of this proximity-fixation-disparity curve is an individual parameter of the vergence system. Actual or potential applications of this research include recommendations for the comfortable viewing distance of visual displays.

Accommodation, Ocular↗
PubMed2000

Meta-analysis of dietary essential fatty acids and long-chain polyunsaturated fatty acids as they relate to visual resolution acuity in healthy preterm infants.

OBJECTIVE: To derive combined estimates of visual resolution acuity differences between healthy preterm infants consuming different compositions and ratios of essential fatty acids (EFAs) and docosahexaenoic acid (DHA), an omega-3 (n-3) long-chain polyunsaturated fatty acid (LCPUFA). DATA SOURCES: Electronic biomedical reference database (Medline and Health Star from 1965 to July 1999) searches with index terms omega-3, n-3, infant, vision, acuity, and human. Current review article, monograph, and book chapter bibliography/reference section hand searches. STUDY SELECTION: A total of 5 original articles and 4 review chapters were reviewed for details on study design, conduct, and outcome. Four prospective trials of EFA/LCPUFA supplementation were included in these analyses. For behaviorally based outcomes, there were 2 randomized comparisons each at </=1, 2, 6, 9, and 12 months of corrected age and 4 randomized comparisons at 4 months of corrected age. For electrophysiologically based outcomes (visual-evoked potential), there were 2 randomized comparisons each at </=1 and approximately 4 months of corrected age. DATA EXTRACTION: Dietary composition and EFA/LCPUFA balance, study design, and analytic characteristics (duration of feeding, source of EFAs/LCPUFAs, number of subjects in study population, number of subjects analyzed, and basis for estimating age), and experiment-based characteristics (location, number or sites, design, vision tests employed, testing protocol, and ophthalmic examination) were recorded independently by 2 researchers with a standardized protocol. DATA SYNTHESIS: The relative difference in visual resolution acuity between groups of infants who received a source of dietary EFAs/LCPUFAs and groups who did not was computed and then analyzed with the DerSimonian and Laird random-effects method. RESULTS: Analysis of the randomized comparisons (DHA-supplemented formula vs DHA-free formula) showed significant differences in visual resolution acuity at 2 and 4 months of age. Combined estimates of behaviorally based visual resolution acuity differences at these ages were.47 +/-.14 octaves and.28 +/-.08 octaves, respectively. A 1-octave difference is a reduction in the width of the stimulus elements by 50%. CONCLUSION: These results support efficacy of n-3 LCPUFA intake in early visual system development, although supplementation safety issues still must be addressed through larger randomized trials. Whether n-3 intake confers lasting advantage in visually based process development across the life-span is still to be determined.

Dietary Supplements↗
PubMed2002

Vision-specific instruments for the assessment of health-related quality of life and visual functioning: a literature review.

Clinically objective measures such as visual acuity or visual field provide an assessment of a patient's visual status. However such measures may not reflect the degree of visual impairment the patient experiences in his or her daily activities. Visual impairment has been shown to have negative effects on health-related quality of life (HR-QOL) and a significant impact on daily functioning, including social activities. As such, there is a growing recognition of the importance of patient-reported outcomes of visual functioning. This review examines the development and psychometric properties of 22 vision-specific instruments assessing visual functioning and/or the impact of visual impairment on HR-QOL or daily activities. Issues relevant to assessing vision-specific subjective outcomes are reviewed, with specific application of the reviewed instruments. Three instruments, the Activities of Daily Vision Scale, National Eye Institute Visual Function Questionnaire, and Visual Function Index have been well validated and widely used, but others also show promise. To fully capture the benefits of a new ophthalmology treatment (or new treatment for eye disease) a valid and reliable visual instrument, in which the psychometric performance has been demonstrated in the particular ocular condition being treated, should be utilised.

Humans↗
PubMedDate not supplied

Prediction of diabetic retinopathy from clinical variables and color vision data.

Predictions about the onset of retinopathy in 295 diabetic patients, all originally having no evidence of retinopathy, have been made in a longitudinal study over 7 yr. Out of many color vision tests and clinical variables, the best individual predictor was a measure of yellow-blue discrimination, using an anomaloscope. The other predictors of significance were the degree of blood glucose control and the duration of diabetes. Although the predictions from a linear logistic model were significant in classifying the diabetic subjects into those whose fundus will remain normal and those in whom it will develop retinopathy, the number of misclassifications was substantial. An examination of the goodness of fit between the data and the model suggested a criterion value (P) of around P = 0.3 for the probability that a patient develops retinopathy. At this value, the probability of being normal for an individual classed as normal was 0.82, and the probability of developing retinopathy for an individual classed as having retinopathy was 0.54.

Adult↗
PubMed1981

A psychometric approach to the measurement of color preference.

A three-part investigation was conducted to explore the meaning of color preferences. Phase 1 used a Q-sort technique to assess intra-individual stability of preferences over 5 wk. Phase 2 used principal components analysis to discern the manner in which preferences were being made. Phase 3 used canonical correlation to evaluate a hypothesized relationship between color preferences and personality, with five scales of the Personality Research Form serving as the criterion measure. Munsell standard papers, a standard light source, and a color vision test were among control devices applied. There were marked differences in stability of color preferences. Sex differences in intra-individual stability were also apparent among the 90 subjects. An interaction of hue and lightness appeared to underlie such judgments when saturation was kept constant. An unexpected breakdown in control pointed toward the possibly powerful effect of surface finish upon color preference. No relationship to five manifest needs were found. It was concluded that the beginning steps had been undertaken toward psychometric development of a reliable technique for the measurement of color preference.

Adult↗
PubMed1986

Follow up of babies delivered in a randomized controlled comparison of vacuum extraction and forceps delivery.

Babies delivered in a randomized controlled comparison of vacuum extraction vs. forceps delivery were reassessed at 9 months of age. There were no statistically significant differences between the two groups as regards head circumference, weight, or head circumference to weight ratio, nor in the results of hearing and vision tests. The reasons for hospital readmission, pediatric follow-up and parents' and health visitors' worries appeared to be unrelated to the mode of delivery in nearly all cases. The finding in the original trial that neonatal jaundice was more common following vacuum extraction was reinforced by an additional case of jaundice in the vacuum extractor group which had necessitated readmission to hospital.

Child Development↗
PubMed1986

High myopia does not affect contrast sensitivity.

The axial elongation of high myopia is known to induce tangential stretching forces on the retina. Such forces might be expected to compromise retinal circuitry and thus affect the temporal and spatial contrast sensitivity function. In fact, we find that simple high myopes have normal contrast sensitivity for stationary gratings, moving gratings, and uniform field flicker. This suggests that, unlike many other retinal disease processes, the high myope's retina retains its normal integrity until the outer retina is compromised.

Adult↗
PubMed1988

Effect of target contrast and luminance on soft contact lens and spectacle visual performance.

The visual performance of four soft contact lenses was investigated using visual acuity charts at six contrast levels (from 90 to 8%) under normal (250cd/m2) and reduced 92.5cd/m2) luminances. This investigation reveals significant differences not detected by conventional visual acuity measurements; in general, reducing luminance or contrast increases the magnitude of any recorded difference. Furthermore, the study pointed to a significantly poorer visual performance with spectacles compared to standard thickness soft contact lenses under low luminance and contrast conditions. Finally, a recommended examination routine is described.

Adult↗
PubMed1990

Neuro-ophthalmological assessment of vision before and after radiation therapy alone for pituitary macroadenomas.

Between 1972 and 1988, 25 patients were treated by radiation therapy (RT) alone for pituitary macroadenomas causing visual impairment. Twenty-three patients were evaluated by a neuro-ophthalmologist before treatment and at the time of follow-up review. Radiation treatment consisted of 4000 to 5000 cGy over 4 to 5 weeks. The median follow-up period was 36 months (range 2 to 192 months). Eighteen patients (78%) experienced visual field improvement. Deterioration occurred in four patients due to tumor recurrence, tumor hemorrhage, possible optic nerve necrosis, and optic chiasm herniation. Visual field improvement occurred predominantly in patients whose pretreatment visual field defects were less than a dense hemianopsia, who did not have diffuse optic atrophy, and who were younger than the median age of 69 years (p less than 0.001). Visual acuity improvement occurred in patients without diffuse optic atrophy, with only mild impairment of the visual acuity, and with only mild visual field loss prior to RT (p less than 0.002). It is concluded that there is a subset of patients with pituitary macroadenomas and visual impairment for whom primary RT is a treatment option.

Adenoma↗
PubMed2000

Optic neuritis after bee sting.

The purpose of this report is to document an unusual case of fully recovered vision after optic neuritis caused by bee sting. A 46-year-old man presented with sudden visual loss after being stung by a bee on the left conjunctiva. He developed optic disc swelling and there was a delay in the P100 wave of the pattern visual evoked potential (VEP). The patient received acute treatment, with intravenous methylprednisolone followed by oral prednisolone. Two days later, visual acuity in the left eye was recovered to 20/20 and P100 latency in pattern VEP was also normalized. Furthermore, visual field and color vision tests revealed no remaining abnormalities. This case suggests that early corticosteroid treatment is effective in optic neuritis caused by bee sting.

Animals↗
PubMedDate not supplied

Long-term stability of alignment in the monofixation syndrome.

From a collection of 328 patients with congenital esotropia, 80 patients were identified who had a minimum 4-year follow-up after surgical alignment within 8 prism diopters (pd) of orthophoria. These patients were subdivided into two groups: the M.S. group (38 patients) demonstrated the monofixation syndrome; the NO M.S. group (42 patients) did not have monofixation. The alignment of patients in each group was followed over time. After 17.5 years, 74% of patients in the M.S. group maintained alignment within 8 pd of orthophoria. In the NO M.S. group, only 45% were well aligned after 14 years. The mean time to loss of stability was significantly shorter for the NO M.S. group (P less than 0.005). Our findings suggest achievement of the monofixation syndrome improves but does not guarantee stability of ocular alignment.

Amblyopia↗