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KMID : 1011420140190010093
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Journal of Korean Ophthalmic Optics Society
2014 Volume.19 No. 1 p.93 ~ p.98
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Individual Difference in the Decrease of Visual Acuity and the Change in Contrast Threshold According to the Level of Optically Induced Retinal Defocus
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Kim Sang-Yeob
Moon Byeong-Yeon
Cho Hyun-Gug
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Abstract
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Purpose: We were aim to investigate individual difference of visual acuity (VA) decrease and the change of contrast threshold (CT) according to the level of optically induced retinal defocus.
Methods: A total of 69 eyes were examined using consist of ten-graded decimal vision chart (Landolt’s ring). After conducted full correction of subject’s refractive error, a monocular VA and CT were measured according to sequential increase by 0.25 D each time.
Results: VA gradually decreased according to the increase of retinal defocus level. Individual difference of VA decrease was range from 1.2 to 0.6 in retinal defocus induced by +0.25 D. When retinal defocus was induced as much as +0.50 D and +0.75 D, it was in the range of 1.0 to 0.3 and 0.9 to 0.1 respectively. With +1.00 D, some participants didn’t even recognize the 0.1 in the chart. With +1.75 D, whole participant did not recognize the 0.1. Also, CT was gradually decreased with increase of the retinal defocus level.
Conclusions: Examiners should consider individual difference in the decrease of VA according to the level of residual
refractive error when determining final prescription of a patient.
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KEYWORD
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Retinal defocus, Decrease of visual acuity, Contrast threshold, Individual difference
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