Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Subjective type
Patent
1999-01-22
2000-11-07
Manuel, George
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Subjective type
A61B 300
Patent
active
061426318
ABSTRACT:
An improved visual acuity chart is disclosed. The ratio of the size of the optotypes of neighbouring lines on the chart is a constant and preferably the size decrement between lines is 0.1 logMAR. Each line of optotypes has two, three or four optotypes, preferably three. Crowding bars for visual acuity charts are also disclosed. These bars are spaced from the ends of row and/or above and below the top and bottom lines. The individual bars may be joined together with linking sections. The spacing form the optotypes is preferably one half the width or height of the optotypes and their breadth is preferably that of the strokes of the optotypes.
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Fitzke Fred W.
Laidlaw D. Allstair H.
Murdoch Ian E.
Rosser Dan A.
Manuel George
Moorfields Eye Hospital NHS Trust
University College London
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