Visual acuity scored by the letter-by-letter or probit methods has lower retest variability than the line assignment method
نویسندگان
چکیده
منابع مشابه
On the statistical reliability of letter-chart visual acuity measurements.
PURPOSE To determine boundary values of test-retest reliability and sensitivity to acuity change that are unlikely to be exceeded in any clinical situation, for a popular visual acuity chart (Lighthouse/ETDRS) with three scoring methods; to discuss general methodological issues associated with statistical accuracy of optotype chart testing; and to link measures of test reliability to measures o...
متن کاملThe pathophysiology of letter-by-letter reading.
Pure alexia is a frequent and incapacitating consequence of left occipitotemporal lesions. It is thought to result from the disruption or the disconnection of the visual word form area (VWFA), a region reproducibly located within the left occipito-temporal sulcus, and encoding the abstract identity of strings of visual letters. Alexic patients often retain effective single letter recognition ab...
متن کاملLuminance effects on visual acuity and small letter contrast sensitivity.
The purpose of this study was to evaluate the effects of luminance on visual acuity (VA) and small letter contrast sensitivity (SLCS). Computer-generated letter charts were used to measure VA and SLCS [6/7.5 (20/25) Snellen equivalent] as a function of stimulus luminance. Letter size (VA) and contrast (SLCS) were varied in equal logarithmic steps, making the task and scoring procedure comparabl...
متن کاملLETTER TO THE EDITORS A CHART DEMONSTRATING VARIXTiONS IN ACUITY WITH RETINAL POSITION Visual acuity
Visual acuity is d&ned as the reciprocal of the visual angle, in minutes. subtended by a just resolvable stimulus. This critical dimension can be the gap in a Landolt C, the spatiat period of a grating or the offset of a vernier. etc. Acuity declines progressively from the fovea out to the periphery of the retina. It is down to half its maximum value at an eccentricity of only 30 min according ...
متن کاملVisual acuity versus letter contrast sensitivity in early cataract
Large and small letter contrast sensitivity and visual acuity were assessed in 37 elderly eyes (mean VA -0.01 logMAR, Snellen 6/6) and their lens opacities were categorised and graded using the LOCS III system. Large letter contrast sensitivity was often not reduced in cataract from age-matched normal values and provided limited information. Small letter contrast sensitivity was shown to be a m...
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ژورنال
عنوان ژورنال: Eye
سال: 1997
ISSN: 0950-222X,1476-5454
DOI: 10.1038/eye.1997.87