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KMID : 1011420130180040549
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Journal of Korean Ophthalmic Optics Society
2013 Volume.18 No. 4 p.549 ~ p.554
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Minimal Illumination to Identify the Chart in Each Visual Acuity and Deviation of Identification Capability According to Illumination and Chart Contrast
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Kim Sang-Yeob
Cho Hyun-Gug
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Abstract
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Purpose:To determine the minimal illumination for visual acuity with the decimal vision chart and individual
difference with varying contrast and illumination.
Methods:Landolt’s vision chart with 10 different grade of
contrast was made. Minimal illumination was measured for 69 eyes using 100% contrast vision chart. Minimal
contrast for identifying the chart was measured in conditions of the minimal illumination and 230 lx, respectively.
Results:Minimal illumination was gradually increased with decrease of the chart size. Mean of minimal
illumination to identify the 1.0 visual acuity was 74.39±25.90 lx with range of 17~107 lx. In conditions of the
minimal illumination and 230 lx, the minimal contrast for identifying the chart were gradually increased with
decrease of the chart size in both conditions, the those deviation for 69 eyes was also increased.
Conclusions:For refractive correction, examiners need to consider the individual difference for identifying the visual chart according to illumination and contrast.
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KEYWORD
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Minimal illumination , Chart contrast , Identification capability
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