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At least 1,495 records · Page 83Linked to original sources
PubMed1968

New method of screening young children for defects in visual acuity.

The methods used at present for screening young children's vision have disadvantages, such as that the child's intelligence can affect the result. In a new method three white cards are used; these are printed with one, two, or three black blocks arranged so that if a child can correctly state the number of blocks at 6 metres the visual acuity is at least 6/9. When tested on 186 children the new method gave better results than conventional tests; eight children with defective vision were picked up only by the new method and none were missed.

Child↗
PubMed1991

Contrast-sensitivity loss in a group of former microelectronics workers with normal visual acuity.

The measurement of contrast sensitivity at varying grating frequencies is used increasingly to study visual and neural disorders. It provides more information than conventional acuity measures. Refractive errors initially affect high spatial frequencies, whereas lower spatial frequencies are affected only when these errors are pronounced. Neurophysiological alterations are reflected by depressed sensitivity to coarse gratings. Visual dysfunction has been associated with workplace exposures to a wide range of organic solvents. In microelectronics assembly where large quantities of organic solvents are used in many aspects of the work processes, visual deficits have been observed. The objective of the present study was to compare contrast sensitivity among former microelectronics assembly workers, with normal far and near visual acuity, and a reference group from the same region, with similar acuity. No significant differences were observed between scores at the two ends of the contrast sensitivity curves; however, at the intermediate spatial frequencies, the former microelectronics workers' scores were significantly lower (Student's t-test; p less than 0.05). For the microelectronics workers, no relation was observed between age and contrast sensitivity at any spatial frequency, whereas for the reference group, contrast sensitivity scores were progressively lower with age at spatial frequencies greater than or equal to 6.0 cpd (r2 = 0.15 at 6 cpd to r2 = 0.45 at 18.0 cpd), suggesting that for the former there is some form of interference with the expected contrast sensitivity loss with age. Lower contrast sensitivity scores in intermediate spatial frequencies, observed among the former microelectronics workers, possibly reflect neural alterations, which may have resulted from exposure to neurotoxic substances. These findings suggest the need for further studies on visual functions in microelectronics workers.

Adult↗
PubMed2002

Visual acuity impairment and mortality in US adults.

OBJECTIVE: To examine the associations between reported visual impairment (VI) and mortality in a nationally representative sample of US adults. METHODS: The National Health Interview Survey is a multistage probability survey of the US civilian population. Adults within households were administered questions about VI and selected eye diseases (n = 116 796). Mortality linkage data with more than 96% of the 1986-1994 survey participants were available through December 31, 1997. Statistical analyses included Cox proportional hazards regression analysis. MAIN OUTCOME MEASURES: All-cause, cardiovascular disease-related, and cancer-related mortality. RESULTS: A total of 327 participants (0.3%) had severe bilateral VI; an additional 4754 (4%) had some VI and/or severe VI in at least one eye. Mortality linkage identified 8949 deaths. After controlling for survey design, age, race, marital status, educational level, reported health status, glaucoma, cataract, and retinopathy, women, but not men, with reported severe bilateral VI were at a significantly increased risk of death relative to their counterparts without VI (hazard ratio [95% confidence interval], 2.21 [1.61-3.02] and 1.33 [0.96-1.84], respectively); risk of mortality was also slightly but significantly elevated in women and men with some reported VI compared with those reporting no VI. Similar patterns of associations were found for cardiovascular disease-related mortality. Risk of cancer-related mortality was not associated with VI. CONCLUSION: Reported severe bilateral VI and, to a smaller extent, less severe VI are associated with an increased risk of all-cause mortality and cardiovascular disease-related mortality in US women; there is weaker evidence for an association between VI and mortality in US men.

Adolescent↗
PubMed2003

Visual acuity as a function of Zernike mode and level of root mean square error.

BACKGROUND: The coefficients of normalized Zernike expansion are orthogonal and reflect the relative contribution of each mode to the total root mean square (RMS) wavefront error. The relationship between the level of RMS wavefront error within a mode and its effect on visual performance is unknown. PURPOSE: To determine for various levels of RMS wavefront error how each mode of the normalized Zernike expansion for the second, third, and fourth orders affect high- and low-contrast acuity. METHODS: Three healthy optimally corrected cyclopleged subjects read aberrated and unaberrated high- and low-contrast logarithm of the minimum angle of resolution acuity charts monocularly through a 3-mm artificial pupil. Acuity was defined by the total number of letters read correctly up to the fifth miss. Aberrated and unaberrated charts were generated using a program called CTView. Six levels of RMS wavefront error were used (0.00, 0.05, 0.10, 0.15, 0.20, and 0.25 microm). Each level of RMS error was loaded into each mode of the second, third, and fourth radial orders individually for a total of 72 charts. Data were normalized by subject, and the normalized data were averaged across subjects. RESULTS: Across modes and within each mode as the level of RMS wavefront error increased above 0.05 microm of RMS wavefront error, visual acuity decreased in a linear fashion. Slopes of the linear fits varied depending on the mode. Modes near the center of the Zernike pyramid had steeper slopes than those near the edge. CONCLUSIONS: Increasing the RMS error within any single mode of the normalized Zernike expansion decreases visual acuity in a linear fashion. The slope of the best fitting linear equation varies with Zernike mode. Slopes near the center of the Zernike pyramid are steeper than those near the edge. Although the normalized Zernike expansion parcels RMS error orthogonally, the resulting effects on visual performance as measured by visual acuity are not orthogonal. New metrics of the combined effects of the optical and the neural transfer functions that are predictive of visual performance need to be developed.

Adult↗
PubMed1988

[2 new visual acuity tests for children: the Cadet letters and Cadet images].

The authors present two new visual tests for preschool children: the Cadet letters and the Cadet images, work of the Cadet (Cercle d'Action et de Dépistage des Troubles visuels de l'enfant). The Cadet lettres prospects the angular acuity of children on and after three years. The Cadet images prospects the psychomorphoscopic visual acuity of children on and after two years.

Child, Preschool↗