• Journal of Korean Ophthalmic Optics Society
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• v.18 no.4
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• pp.373-383
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• 2013

Purpose: In this study, we analyzed refractive power of school children in low income family. Methods: We have done a comparative analysis with 112 subjects of low-income of 17 elementary schools in the Yeongcheon area and low-income children less than -6 D of refractive errors from the Korean National Health and Nutrition Examination Survey Report 2010. Results: Spherical equivalent (SE) with low-income group of nation was -1.99 D for right eye and -1.81 D for left eye, while high income group of nation showed -1.26 D and -1.21 D for right eye and left eye respectively. The SE with low income group in Yeongcheon area was -1.85 D for right eye and -1.81 D for left eye. The SE with orphan was -2.75 D and -2.42 D. Single parent family was -2.10 D and -1.96 D, and two parent family was -1.75 D and -1.73. Conclusions: The lack of attention to children eye care may be one of cause for myopia, so the role of the parents and teacher is very important. However, limited role of parents to children due to low income, it is necessary to provide an institutional strategy and social interest to prevent children vision' in low income family.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.1
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• pp.39-45
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• 2009

Purpose: The purpose of this study is to compare the visual performance by contrast sensitivity (CS) and disability glare (DG) in low astigmatic eyes corrected with toric soft lenses and other optical corrections. Methods: Twenty university students with myopia (-1.00 to -6.50D Sph. with astigmatism up to 1.50 cyl) were enrolled and corrected by five different methods: 1) soft toric lenses; 2) spherical soft contact lenses; 3) RGP lenses; 4) best spectacle corrected visual acuity; 5) spherical equivalent spectacles. All subjects had corrected vision acuity of 20/20 or better. Contrast sensitivity and disability glare were measured using the OPTEC 6500 contrast sensitivity view-in tester included the EyeView Functional Vision Analysis software at photopic or mesopic conditions with glare. Results: At photopic condition, best corrected spectacle wearers had the highest monocular contrast sensitivity at all spatial frequency followed by soft toric lenses, RGP lenses, spherical equivalent spectacles, and spherical soft contact lenses. However, all of them were in normal contrast sensitivity value at photopic condition. At mesopic condition with glare, toric soft lenses were the highest and followed by RGP lenses, spherical equivalent spectacles, best spectacle corrected visual acuity and spherical soft contact lenses. It was observed that spherical soft contact lens wearers demonstrated lower range than normal contrast sensitivity value at mesopic condition with glare. Conclusion: Toric soft lenses gave better visual performance than spherical soft lenses in low astigmatic eyes. Subjects requiring the use of contact lenses under mesophic conditions could benefit from toric soft lenses.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.4
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• pp.501-509
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• 2015

Purpose: To evaluate the reliability of refractive power by comparing the marked refractive power in an automatic phoropter and actually measured spherical/cylindrical refractive power. Methods: Actual refractive power of minus spherical lens and cylindrical lens in an automatic phoropter was measured by a manual lensmeter and compared with the accuracy of marked refractive power. Furthermore, combined refractive power and spherical equivalent refractive power of two overlapped lenses were compared and evaluated with the refractive power of trial lens. Results: An error of 0.125 D and more against the marked degree was observed in 70.6% of spherical refractive power of spherical lens which is built in phoropter, and the higher error was shown with increasing refractive power. Single cylindrical refractive power of cylindrical lens is almost equivalent to the marked degree. Combined spherical refractive power was equivalent to spherical refractive power of single lens when spherical lens and cylindrical lens were overlapped in a phoropter. Thus, there was no change in spherical refractive power by lens overlapping. However, there was a great difference, which suggest the effect induced by overlapping between cylindrical refractive power and the marked degree when spherical lens and cylindrical lens were overlapped. Spherical equivalent refractive power measured by using a phoropter was lower than that estimated by trial glasses frame and marked degree. The difference was bigger with higher refractive power. Conclusions: When assessment of visual acuity is made by using an automatic phoropter for high myopes or myopic astigmatism, some difference against the marked degree may be produced and they may be overcorrected which suggests that improvement is required.

• Journal of Digital Convergence
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• v.12 no.12
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• pp.485-490
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• 2014

The purpose of this Study investigated corneal power, corneal astigmatism and corneal axis according to spherical equivalent of refractive error. We measured spherical equivalent, corneal power and corneal astigmatism in 100 subjects from January 2014 to July 2014. Measured spherical equivalent of refractive error were $-3.01{\pm}3.79D$, corneal power of $43.79{\pm}1.60D$ and corneal astigmatism of $-1.17{\pm}0.79D$ respectively. Prevalence of spherical equivalent of refractive error were as follows : myopes (61%), emmetropes (22%), hyperopes(17%). Corneal astigmatism of refractive error greater than +0.75D was 63% and prevalence of corneal astigmatism were as follows : with-the-rlue astigmatism (84.13%), against-the-rule astigmatism(9.52%) respectively. Corneal power by spherical equivalent increased from hyperopia to myopia. Between spherical equivalent of refractive error and the mean corneal power was significant correlation(r=-0.25, p=0.01). A correlation were found between corneal power and spherical equivalent of refractive error in adults. They have the highest distribution of prevalence myopia among the refractive error. When the refractive error was increased, we found that corneal power was steeper. It is recognized that this can be refractive error factor and correct visual function is considered.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.2
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• pp.167-170
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• 2011

Purpose: This study was tried whether expectation of astigmatism from spherical equivalent visual acuity was possible. Methods: For 54 men and women (108 eyes) corrected to emmetropia, average age of 23.3, changes of visual acuity (5m) were measured with an increasing the powers at every ${\pm}$0.25D when the (-) axis of cross cylinder is $180^{\circ}$, $90^{\circ}$, and $45^{\circ}$, respectively. Results: As the power of cross cylinder was increased, visual acuity was decreased. When the powers of cross cylinder were ${\pm}$2.50D ($180^{\circ}$ and $90^{\circ}$) and ${\pm}$2.25D ($45^{\circ}$), visual acuity was 0.05 which is the minimum measurement possible. Conclusions: The diagram on astigmatism dealing with each spherical equivalent visual acuity was able to tabulate.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.1
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• pp.55-62
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• 2006

Clinical evaluation of the Closed-view autorefractor and Open-view autorefractor was performed to examine validity and repeatability compared with subjective refraction. Measurements of refractive error were performed on 126 eyes of 65 subjects (aged $26{\pm}7.5$ years) subjectively noncycloplegic. Intersession repeatability of the Closed-view and Open-view were also assessed on all 65 subjects together with Intersession repeatability on 7 to 14 days intervals. Spherical powers and spherical equivalent values of subjective refraction and autorefractions by Closed-view and Open-view were analyzed by paired T-test. The mean spherical powers of subjective refraction, Closed-view and Open-view were determined to be $-2.125{\pm}2.155D$, $-2.146{\pm}1.907D$, $-2.117{\pm}2.121D$, respectively. The mean spherical equivalent values of subjective refraction, Closed-view and Open-view were determined to be $-2.362{\pm}2.204D$, $-2.391{\pm}1.967D$, $-2.366{\pm}2.162D$, respectively. The results showed that the refractive errors as measured by the Closed-view and Open-view were found to be similar to the subjective refraction in all components.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.2
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• pp.197-202
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• 2013

Purpose: This research was performed to measure and analyze scotopic pupil size in myopes and to figure out the factors that influence it. Methods: The pupil size of 191 healthy myopic subjects were measured with the pupillometer (Colvard pupillometer, OASIS medical, USA) in scotopic and analyzed with the age, corneal size, spherical equivalent refractive error, corneal curvature. In addition, it was compared with the measurements of intra-examiner and inter-examiner to verify reproducibility of pupillometer. Results: The mean (${\pm}$SD) scotopic pupil size was $6.64{\pm}0.68$ mm (range, 5.00~8.00 mm), the lower age and the larger corneal size, The bigger the pupil size. The lower spherical equivalent refractive error and steepper corneal curvature tends to be smaller. The reproducibility of intra-examiner and inter-examiner in pupillometer showed the reliability highly (Guttman splithalf point > 0.91). Conclusions: The pupil size associated with age, corneal size, spherical equivalent refractive error and corneal curvature in scotopic condition. It can refer to prevent inconvenience that may occur RGP contact lenses, cataract surgery and refractive surgery.

• Journal of Digital Convergence
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• v.14 no.11
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• pp.435-440
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• 2016

The aim of study was to provide the preliminary data to find out characteristics of the difference between both refractive errors through analysis of ocular components variation. We measured spherical equivalent power and corneal radius with KR-8800, and axial length and anterior chamber depth with IOL Master, and the difference of measuring values between the right eye and left eye was applied as the absolute values in 100 adults aged 20~59 years. In all participants, the most common results showed that spherical equivalent power was $-1.83{\pm}2.17D$, axial length was 23.00~24.99mm, corneal radius was 7.50~7.89mm, and anterior chamber depth was 3.60~4.09mm. There are significant correlations between both eyes in axial length and anterior chamber depth with the difference of both spherical equivalent power. The difference of both axial lengths was the biggest with the difference of both refractive errors, and shown the highest correlation. The convergence complex study through classification by aspects is needed since the difference of both refractive errors is closely related with ocular components variation, and poor visual function would be caused by the difference of both refractive errors.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.125-129
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• 2008

Purpose: To research the study of abnormal refraction eye on women population of university students in South - East Korea. Methods: Between March 2007 and October 2007, the refraction test of eye glasses wearer was evaluated on women population (367 students, aged 19~22 years) of university in living on Kyung-Nam and Pusan province. Data was analysed with T-test. Results: On the abnormal refraction status, Compound Myopic Astigmatism was 76.72%, simple myopia was 10.90%, mixed astigmatism was 6.27%, respectively. On the prevalence of myopic power, low was 59.57%, moderate was 24.93%, high was 15.49%, respectively. On the myopic equivalent power, the right eye had more increase to compare to left eye. but these was not a statically significant correlation (p<0.5) between the right and left eyes. On the anisometropia of spherical equivalents and cylinder power, most subjects was under 1.0 diopter. On the other hand, the type of astigmatic axis was with-the rule (70.79%), against -the rule (18.41%), and oblique (10.80%). Conclusions: This study identify that the refraction status of abnormal refraction eye on women population in university students in South-East Korea have been more increased prevalence the myopia and astigmatism.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.2
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• pp.109-114
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• 2006

We evaluated the contour using corneal asphericity of the myopic cornea in Korea and investigated the relationship between refractive error and other ocular dimensions in Korean myopia, including anterior chamber depth and asphericity. The monoocular asphericity value of 50 myopes with $-4.83{\pm}2.38$ D between early 20 age and early 30 age in adult was included. Cycloplegic refraction, corneal asphericity and anterior chamber depth using corneal topography were examined. The mean asphericity values were$-0.27{\pm}0.13$ and the corneas of 96.0% were prolate ellipse. Refractive error was related to asphericity and anterior chamber depth among myopes. However, asphericity only were significant difference in high and low myopia group. Corneal configuration on the contact lens fits are discussed. We think that the longitudinal study for myopia and asphericity was required.