A percentile vision chart

Abstract

Disclosed is a centesimal visual acuity chart. The centesimal visual acuity chart is characterized in that a centesimal system is adopted to express visual acuity, so that the better the visual acuity is, the higher the score. Each visual target of the visual acuity chart is in the shape of a notched ring, a notch is fan-shaped, a circle center angle is 12.76 degrees, width of the ring is equal to that of the middle of the notch, outer diameter of the ring is 10 times of width of the ring while inner diameter of the same is 8 times of width of the ring, size of the visual targets is in continuous gradient changing, and a vision score difference of each gradient is 10 scores.100 scores is for a test of 5 m, the width of the middle of the notch is 1.454 mm, the visual target of 100 scores is taken as a base point, the size of the visual targets of 90 scores and lower scores is sequentially increased progressively outward by 1.25 times, and the size of the visual targets of 110 scores and higher scores is sequentially decreased progressively inward by 0.8 time. The visual targets can sleeved and overlapped at intervals according to size order to form four groups to be combined into the visual acuity chart, and size of the visual acuity chart is reduced. The visual acuity chart can be made into an electronic product, namely a visual acuity tester, by using a led semitic form to increase interestingness when visual acuity of children is tested.

Description

technical field

[0001] The invention relates to an eye chart, in particular to a precise hundred-point eye chart for detecting the resolution ability of human eyes. Background technique

[0002] Existing eye charts include Landolt circular eye chart, i.e. C word chart, logarithmic eye chart and standard eye chart. The latter two are E word charts. The vision chart is designed based on the principle of viewing angle. The standard vision chart measured at 5 meters away is 1.0 and the logarithmic vision chart is 5.0. The viewing angle is 1 point of view (1 degree = 60 points). The visual acuity is the reciprocal of the viewing angle, that is, the =1 / angle of view, if the angle of view is 1, the visual acuity is 1 / 1'=1.0, when the visual angle is 10, the visual acuity is 1 / 10'=0.1, that is, for 1.0 visual acuity, the opening of the letter C (1-point viewing angle) is 1.454 mm, and the outer diameter of the ring It is 1.454×5 mm, the inner diameter of the ring is 1.454×3 mm, the...

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