• Journal of Korean Ophthalmic Optics Society
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• v.17 no.1
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• pp.53-58
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• 2012

Purpose: The purpose of this study was to predict the amount of astigmatism through logMAR visual acuity by Jin's chart at best vision spherical power and to compare availability of astigmatism expectation by Jin's and beam project chart. Methods: LogMAR and decimal visual acuity were measured for 150 college students and visual acuity and compared the amount of astigmatism under full correction. Results: Jin's chart was showed marked differences at least more than 0.25 D intervals per line than beam project chart. Correlation with the amount of astigmatism was higher the logMAR visual acuity r = 0.8578 than decimal visual acuity r = -0.7199. Conclusions: LogMAR visual acuity at best vision spherical power was able to predict to amount of astigmatism and Jin's chart was easier than beam project chart to predict difference of each lines.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.4
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• pp.549-554
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• 2013

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 $74.39{\pm}25.90$ 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.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.1
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• pp.93-98
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• 2014

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.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.4
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• pp.551-555
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• 2014

Purpose: This study is to investigate if the improvement of visual sensory (VS) by amblyopia treatment affects the ocular functions in refractive errors, accommodative errors and phoria at distance and near. Methods: 10 subjects (17 eyes, mean age of $10.7{\pm}2.9$ years) who treated amblyopia completely, were participated for this study. Refractive errors, accommodative errors, and distance and near phoria were compared between before and after treatments of amblyopia. Refractive errors and accommodative errors at 40 cm were measured using openfield auto-refractor (NVision-5001, Shin Nippon, Japan) and using monocular estimated method (MEM) respectively. Phoria was determined at 3 m for distance and at 40 cm for near using Howell phoria card, cover test or Maddox rod. Results: Mean corrected visual acuity (CVA) significantly increased from $0.46{\pm}0.11$ (decimal notation) for before amblyopia treatment to a level of $1.03{\pm}0.13$ for after amblyopia treatment (p < 0.001). For spherical refractive error, hyperopia significantly decreased from $+2.29{\pm}0.86D$ to a level of $+1.1{\pm}2.38D$ (p < 0.05) but astigmatism did not significantly change; $-1.80{\pm}1.41D$ for before treatment and $-1.65{\pm}1.30D$D for after treatment (p > 0.05). Accommodative error significantly decreased from accommodative lag of $+1.1{\pm}0.75D$ to a level of $+0.5{\pm}0.59D$ (accommodative lag) (p < 0.05). Distance phoria significantly changed from eso $2.9{\pm}6.17PD$ (prism diopters) to a level of eso $0.2{\pm}3.49PD$ (p < 0.05), and near phoria also significantly changed from eso $0.4{\pm}2.32PD$ to level of exo $2{\pm}4.9PD$ (p < 0.05). There was a high correlation (r = 0.88, p < 0.001) between improvement of visual acuity and decrease of accommodative lag. Conclusions: Hyperopic refractive error decreased with improvement of CVA or VS by amblyopia treatment. And the improvement of VS by amblyopia treatment also improved accommodative error, and changed phoria coupled with accommodation.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.1
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• pp.59-65
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• 2012

Purpose: The purpose of this study was to determine the distribution and correlation of accommodative lag with refractive error. Method: We had tested the clinical refraction and the accommodative lag in clinically normal 49 young adults (total 98 eyes) aged 18 to 25 years without abnormal binocular function. Monocular and binocular accommodative lag were tested with 0.50 D cross-cylinder lens and near vision test chart which had cross-hairs after full correction of LogMAR visual acuity over 0.05. Results: There was no statistical differences in monocular accommodative lag between right ($0.64{\pm}0.64$ D) and left eye ($0.63{\pm}0.64$)(p=0.858). The accommodative lag of male was higher than female and the range of the value was broader than female in binocular accommodative lag (p=0.015). The wider the inter-pupillary distance was, the higher the accommodative lag was (p=0.003). However, there were no differences with age (p=0.800) and dominant eye (p=0.402). The ranges of accommodative lag of low, middle, and high myopia were 0.75 ~ -0.25 D, 1.25 ~ -0.50 D, and 1.50 ~ -0.75 D, respectively, and the regression was 'y = -0.03953x+0.09205'. Conclusions: These data suggest that clinically normal young adults with high amounts of refractive error have more variable accommodative lag and increased spherical equivalent refraction.

• Journal of Digital Convergence
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• v.14 no.10
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• pp.375-380
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• 2016

This study aimed to evaluate the possibility for assessment of binocular visual function about alteration for near point of convergence (NPC). Study subjects were total 30 (emmetropia 16, myopia 14), who had no eye disease except for the phoria and monocular corrected vision 1.0 and over. Near point of accommodation (NPA), NPC and phoria test were measured both at ordinary and stimulation of +1D. Ordinary NPC was 1.77cm shorter than NPC stimulated +1D and the NPC of emmetropia was shorter than that of myopia. The difference between NPC stimulated +1D and ordinary were increased in the emmetropia. As the NPC increased, the AC/A ratio was elevated and the feature of near exophoria appeared. The results suggested that the alteration of NPC might substitute AC/A ratio for reference variable of binocular vision. If converged and analyzed comparatively with another binocular visual evaluation test, the alteration of NPC could be developed for substitution of evaluation test.