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Results for “Vision Tests”

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At least 127 records · Page 7Linked to original sources
PubMed2000

A method for using relay lenses with display monitors for vision testing at far and near.

Resolution limitations preclude the use of display monitors for near testing of acuity and contrast sensitivity. Relay lenses can form minified aerial images of the display at any given near viewing distance, but the image will differ in spatial frequency from the display. Equations are presented that can be used to specify the far- and near-viewing distances and the necessary focal length of a lens so that the display and its near aerial image have identical spatial frequencies when viewed by a subject at a fixed location. Modulation transfer function (MTF) calculations show that achromatic doublets will not degrade the resolution across a 300-mm wide display, thereby providing the versatility of display monitors for near vision testing.

Computer Terminals↗
PubMed1980

Cool white, Ultralume, and Vita-Lite fluorescent lamps for use in color vision testing.

Thirty-one normal and 20 color vision-deficient persons were tested with the Hardy-Rand-Rittler (HRR) Pseudoisochromatic Plates, Farnsworth's D-15 and 100-Hue tests, and the Davidson & Hemmendinger (D & H) Color Rule using Vita-Lite, Ultralume, and Cool White fluorescent lamps to determine their usefulness for color vision measurement. The persons with deficient color vision were classified with a Nagel anomaloscope. The Macbeth Easel lamp was the reference for determining relative lamp performance. No normal was misclassified with any of the lamps. Scores with the Vita-Lite lamp were qualitatively and quantitatively most similar to those with the Macbeth lamp. The Ultralume gave intermediate results, and the Cool White was the least satisfactory substitute. Norms for the metameric D & H Color Rule for each lamp were different, which prevented intercomparisons. Best separation of the scores of deficient from normal persons with the D & H Rule occurred with the Macbeth and Vita-Lite lamps. Better performance with the Vita-Lite and Ultralume lamps can be expected from protans with the HRR and 100-Hue Tests and poorer performances from deutans on the HRR tests than with the standard Macbeth Lamp. The Cool White lamp was judged an unsuitable substitute for color vision testing.

Adolescent↗
PubMed1978

Color vision testing: an alternative 'source' of Illuminant C.

The objective of this project was to evaluate an alternative procedure for administering reflective-type color vision tests. In this procedure, the tests are illuminated by a low color-temperature, 100 W, incandescent lamp (i.e. an improper illuminant) and the patient then views the illuminated test elements through an inexpensive gelatin filter placed before his eye (e.g. a Wratten 78AA costing about $4). Since the relative transmittance of this filter is quite similar to that used in the Macbeth Easel Lamp, the tests should still be valid. In fact, this alternative procedure yields test performances for normal and deficient subjects on the 100-hue, panel D-15, and AO H-R-R tests that are virtually identical to those obtained using a standard Macbeth Easel Lamp.

Color Perception Tests↗
PubMed1980

Results of colour vision tests in alcoholic and in mentally disordered subjects.

The responses at the Ishihara test, the Nagel anomaloscope, the standard Panel D--15 and the 100 hue test (with correction of the age effect) were recorded in 38 alcoholics in deprivation period (successively subdivided according to age, to abstinence duration and to liver condition) and in 32 subjects suffering from mental diseases (successively subdivided according to ethylic past, to age, to duration of the stay in the hospital and to activity). It is shown that alcoholism causes a diminution of the performance at the used colour vision tests and especially at the 100 hue test. The defect can be ascribed to psychical factors (chiefly in the cases of mental disease and in the younger people), but also to an acquired blue-yellow defectiveness of colour vision with a shift of the Rayleigh match to red (such a defectiveness can also be due to a liver damage and to some intoxications) and even to a Type II acquired red-green defectiveness of colour vision (possibly by tobacco or disulfiram intoxication). The defect due to alcohol itself soon disappears during desintoxication. The authors draw some practical conclusions.

Adult↗