• Journal of Korean Ophthalmic Optics Society
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• v.14 no.2
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• pp.9-14
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• 2009

Purpose: The purpose of this study was to examine the relationship between the accommodative facility, blink rate and accommodative lag according to the change of angles of main viewpoint of near distance worker and study an appropriate viewing angle that mitigates asthenopia, such as headaches or eye fatigue accompanied when reading and staring at the computer or TV for a long time. Methods: Total of 27 people including 12 male university students and 15 female university students in the age of 20 to 36 with frequent near distance works, such as computers, were selected to study the accommodative facility, the blink rate and the accommodative lag in accordance with the change of viewing angles of the near distance workers. The refraction error was corrected completely and the phoropter was shifted to near distance mode to locate the near distance indication at 40 cm. The accommodative facility and the blink rate were measured for one minute at each viewing direction of $40^{\circ}$ downward, $20^{\circ}$ downward, horizontal, and $20^{\circ}$ upward directions based on the horizontal line and the accommodative lag was measured in dynamic retinoscopy using retinoscope. Results: As a result, when the main viewpoint was moved on upper direction from the $40^{\circ}$ below, the accommodative facility was reduced and the blink rate and the accommodative lag were increased so their eyes became dry and the accommodation response was reduced. Conclusions: In near distance works, the eye fatigue level can be minimized by locating a book or a computer screen $40^{\circ}$ below than the horizontal direction.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.2
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• pp.153-158
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• 2012

Purpose: The purpose of this study was to evaluate the convergence accommodation to convergence (CA/C) ratio and to investigate relationships among age, accommodative amplitude and PD (interpupillary distance) of adults in their early twenties with normal binocular vision. Methods: 44 subjects (mean age, $21.75{\pm}1.16$ years) with healthy eyes were examined. The CA/C ratios were measured by using the difference of Gaussian (DOG) target with retinoscopy. Results: The mean CA/C ratio was $0.052{\pm}0.017$ D/$\Delta$. A moderate negative correction was present between CA/C ratio and age (r = -0.50, p = 0.0005), and a highly positive correction was found between CA/C ratio and accommodative amplitude (r = 0.79, p<0.0001). There was no relation between PD and CA/C ratio. Conclusions: The CA/C ratio presented was mean value for adults in their early twenties with healthy eye between 19 and 25 years of age. There was a high correlation between accommodative amplitude and CA/C ratio. Therefore, the CA/C ratio will be useful basic information for comparison in age, gender and binocular anomalies with similar data from other countries.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.2
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• pp.123-130
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• 2010

Purpose: The study was conducted to compare the values of auto-refraction, manifest refraction and cycloplegic refraction in school-aged children. Methods: One hundred five myopic school children ranged from 6 to 14 years old (210 eyes, $10.28{\pm}1.59$ years old) were recruited and noncycloplegic auto-refraction (AR) and manifest refraction (MR) were conducted and then underwent cycloplegia and refractive status (CR) again with the auto-refractometer. Results: Refractive powers measured by AR, MR, and CR were highly correlated. However, spherical and cylindrical powers of the subjects measured by AR were measured higher negative power than in CR (p<0.001). From 210 eyes, the discrepancy rate in the spherical and cylindrical powers were 40 eyes (19%) and 19 eyes (9%) of the total subjects, respectively and the differences between noncycloplegic and cycloplegic refractions were higher with the spherical and cylindrical powers increasing. Conclusions: The use of the autorefractometer in children with negative spherical power without cycloplegia may overestimate the actual myopia that subjective refraction is the most important in prescription for the eyeglasses and regression equations would be used to prognose the cycloplegic refraction from the auto-refraction as the basic data for the subjective refraction.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.1
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• pp.109-114
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• 2009

Purpose: This study was designed to investigate the condition of refractive correction on wearing glasses currently of elementary school children and their accommodative ability in Jinju city. Methods: Objective refraction, subjective refraction, amplitude of accommodation, negative and positive accommodation, accommodative facility, and dynamic retinoscopy were examined on 60 elemenary school children who aged 8~12 wearing myopiacorrected glasses. Results: The condition of refractive corrections was distributed that a case of full correction was 11.7%, a case of low correction with more than 0.8 visual acuity (VA) was 10%, and a case of low correction with less than 0.8 VA was 78.3% in wearing glasses currently. In results from examination of accommodative ability, the number of children having accommodative anomaly is 8 persons (13.3%), they were divided into accommodation insufficiency (4 persons), accommodative facility insufficiency (2 persons), accommodation excess (1 person), and accommodation insufficiency related to ocular function (1 person). Conclusions: It is demanded a periodic inspection of refractive correction to growing children, and the refractive correction after due consideration to accommodative ability is really needed.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.107-112
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• 2008

urpose: This thesis is a study the Night myopia was surveyed by Subjective refraction and Objective refraction (Dark retinoscopy), and analyzed the relationship between them. It also looked at the relation between Night myopia and pupil size. Methods: 82 adult subjects (ages of 19 to 44, 44 males and 38 females) were examined by Subjective refraction and Objective refraction in the light place. Then Night myopia and pupil size were examined by Subjective refraction and Objective refraction in the dark again. The Statistics were analyzed by SPSS (Statistical Package for Social Science). Results: As the subjects became younger, the observed Night myopia was getting higher in both Subjective refraction, $x^2$=219.48 (p<0.01) and Objective refraction, $x^2$=241.98 (p<0.01). The relationship was statistically significant by showing large pupil size, $x^2$=151.74 (p<0.01). In Objective refraction, as pupil size became larger in the dark place, so did Night myopia, $x^2$=84.27 (p<0.01), reaching a statistically significant correlation, however, the correlation was low in Subjective refraction. In Subjective refraction, observed Night myopia was 73%, 64 examples of 88 examples, a standard of 0.96${\pm}$0.4584D in ${\pm}$0.25D, in male examples, and it was 64%, 49 examples of 76 examples, a standard of 1.01${\pm}$0.4509D in ${\pm}$0.25D, in female examples. In Objective refraction, it was 48%, 42 examples of 88 examples, in standard of 0.85${\pm}$0.4651D in ${\pm}$0.25D, in male examples. And it was 71%, 54 examples of 76 examples, in standard of 0.96${\pm}$0.4133D in ${\pm}$0.25D, in female examples. Conclusions: Night myopia which is measured by both methods, observed as $x^2$=265.35 (p<0.01) and showed a large relationship. The correlation between the two refractions suggests that observed night myopia diopter by Subjective refraction could be used as correction of night myopia.