Results 211 to 220 of about 24,138 (257)

Low-Contrast Letter Charts as a Test of Visual Function

Ophthalmology, 1983
Visual pathway disorders can cause visual loss that is not detected by the Snellen test: visual sensitivity to coarse detail may be depressed, even when visual sensitivity to fine detail is unaffected. Sinewave grating test targets can detect such hidden visual loss. However, electronic apparatus for generating sinewave gratings is expensive, while the
David Regan
exaly   +3 more sources

Contrast Sensitivity Letter Charts as a Test of Visual Function in Amblyopia

Journal of Pediatric Ophthalmology and Strabismus, 1990
ABSTRACT Anisometropie and strabismic amblyopes were studied using the Regan Contrast Sensitivity Charts. At all levels of contrast, the amblyopic eyes of both the strabismic and anisometropic patients scored significantly lower than did their fellow normal eyes, which were used as controls. In comparing the differences between the normal and
M, Loeffler, J S, Wise, M, Gans
exaly   +3 more sources

The Slope of the Psychometric Function for Bailey-Lovie Letter Charts: Defocus Effects and Implications for Modeling Letter-By-Letter Scores

Optometry and Vision Science, 2001
Background. Visual acuity measurement often results in an imprecise endpoint because subjects correctly identify some but not all of the letters on one or more size levels on a letter chart. The extent of this transition zone from seeing to nonseeing can be described by probit size, which is calculated by ...
Andrew Carkeet
exaly   +3 more sources

Letter legibility and chart equivalence

Ophthalmic and Physiological Optics, 2000
Summary Introduction : We tested the appropriateness of the assumption that charts, which only vary in having different sequences of five letters per line, chosen from the same 10 letter set, can be regarded as equivalent for the purpose of making valid comparisons of visual acuity.
C W, McMonnies, A, Ho
openaire   +2 more sources

On the Smith Chart (Letters)

IEEE Transactions on Microwave Theory and Techniques, 1978
The Smith Chart is the complex plane of the reflection coefficient. The unique contribution of P. H. Smith was the superposed grid for identifying impedance or admittance values; however, students, when being introduced to the Chart, can often be caught up in the superposed grid.
openaire   +1 more source

Sans Serif Letters for Snellen Charts

JAMA: The Journal of the American Medical Association, 1970
To the Editor.— A modified Snellen's chart is p-oposed ( Amer J Ophthal 66: 750, 1969) which employs simplified Gothic characters, instead of those usually printed in Gothic Boston Breton type adorned with serifs. Most road signs are designed in the sans serif lettering, and it is suggested that vision-testing of automobile drivers might wisely be ...
openaire   +2 more sources

Chart construction and letter legibility/readability

Ophthalmic and Physiological Optics, 1999
Summary Variation in legibility/readability between charts letters may be due to differences in chart construction and/or examination protocols and/or subject selection. An examination of legibility/readability of letters that are common to two chart constructions was undertaken.
openaire   +2 more sources

Letter Legibility and the Construction of a New Visual Acuity Chart

Ophthalmologica, 2010
The ability to identify letters of different size remains, in relation to the allowed effort, the most informative measure of visual capacity. Numerous letter charts have been produced with varying design, size, and size progression of the letters. Attempts to ‘standardize’ letter testing have been fruitless.
A, Hedin, K, Olsson
openaire   +2 more sources

Measurement of Glare Susceptibility Using Low‐Contrast Letter Charts

Optometry and Vision Science, 1993
ABSTRACT The Committee on Ophthalmic Procedures Assessment of the American Academy of Ophthalmology suggested either contrast sensitivity or low‐contrast visual acuity (VA) measured before and after adding a glare source as a test for assessing overall visual disability from immature cataracts.
D, Regan, D E, Giaschi, B B, Fresco
openaire   +2 more sources

Performance of video‐displayed letter charts

Clinical and Experimental Optometry, 1986
A software package was developed for an Apple-II microcomputer to display Snellen letters as test charts for high speed measurement of visual acuity. With direct viewing of a 30 cm (12 inch) monitor, letter sizes can range from 6/100 to 6/6. This range can be extended by using a modified monitor to display reversed letters for indirect viewing, to ...
openaire   +1 more source