• Journal of Korean Ophthalmic Optics Society
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• v.18 no.3
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• pp.291-295
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• 2013

Purpose: The purpose of this study was to investigate the effect of under and over refractive correction on visual acuity performance and the variation of the visual performance measurement using two different visual acuity charts. Methods: Ten young adults, aged between 19 and 25 years old, were recruited. Inclusion criteria: no history of ocular injury or pathology with a best-corrected visual acuity of 6/6 on dominant eye. The over and under refractive corrections were induced using minus and plus spherical ophthalmic lenses in 0.50 D steps up to 3.00 D; as well as using three axis orientations of cylindrical ophthalmic lenses ($45^{\circ}$, $90^{\circ}$ and $180^{\circ}$) in 0.50 D steps. The variation of visual acuity performance measurements was investigated using Bailey-Lovie LogMAR chart and Landolt C chart. Results: The visual acuity changes with lenses were significantly different between two charts [F = 49.15, p < 0.05 with plus spherical ophthalmic lenses and F = 174.38, p < 0.05 with minus spherical ophthalmic lenses]. The visual acuity changes with three different cylindrical axis showed no significant difference between Bailey-Lovie LogMAR chart [F = 2.35, p > 0.05] and Landolt C chart [F = 3.12, p = 0.05]. Conclusions: The over and under refractive correction affected the visual acuity performance differently. The Landolt C chart and Bailey-Lovie LogMAR chart demonstrated variation in measurements.

• 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.11 no.4
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• pp.337-344
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• 2006

Purpose: To evaluate the vision-specific Quality of Life according to modes of refractive error correction in myopia. Method: This study included subjects from two different universities in Korea during March 2005 to June 2005. The following subjects (470) were university students, university faculty members, and their immediate families; all of whom were over the age of 19 and all who had refractive error of some sort. The four focus groups consisted of 171 spectacle wearers, 154 contact lens wearers, 123 refractive surgery patients, and 22 post-refractive surgery patients who returned to wearing glasses. The study of Vision-Specific Quality of Life used QIRC - The Quality of Life Impact of refractive Correction Questionnaire, which was translated by our group from English into Korean. Using analysis of co-variance (ANCOVA) and adjusting for age, sex, job, economic status, and education level, we examined and compared the QOL mean scores of the three groups (glass & contact lenses wears, refractive surgery patients, and post-refractive surgery patients who returned to wearing glasses). Results: After adjusting for major compounding variance, the research results showed the highest QOL mean score of 43.2 for the group who had received refractive surgery, 37.1 for the glasses & contact lenses group, and 33.4 for patients who had returned to wearing glasses after refractive surgery. There were significant differences between the three groups (p=0.001). Conclusion: Refractive surgery has shown a significant contribution to improve the QOL in myopia patients. However, upon our investigation, patients who underwent refractive surgery and returned to wearing glasses had a lower QOL compared to non-refractive surgery patients who wore glasses/contact lenses. Upon concluding our studies that shows that refractive surgery does not always conclusively bring higher QOL, we would like patients to carefully consider their options before undergoing refractive surgery in the future.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.2
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• pp.345-352
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• 2004

We investigated the effect of age at initial correction, of 44 refractive amblyopic patients duration of correction on corrected visual acuity with the lapse of time for mean 33months(3months-59months). Full cycloplegic corrections were prescribed at the initial visit to all subjects. The distribution of initial corrected visual acuity was 0.02 to 0.5. Age at initial correction varied from 3 years to 12 years. The refractive error appeared to have the greatest influence on the visual outcome, showing continuous visual improvement after initial correction. But the age at initial correction did not appear to influence on the initial and final corrected visual acuity showed a significant difference, irrespective of age at the initial correction Or degree of anisometropia.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.1
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• pp.103-108
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• 2009

Purpose: The objective of this study is to compare and analyze the wearing status of refractive error correction devices of elders who reside in a city or in a small town district. Methods: Each of opticians from a small town or a city was selected for the study of wearing status of presbyopia correction device for each residential district in units of percentage. with the analysis of the age and gender distributions of the elders, numbers of elderly members, and the kinds of presbyopia correction. Results: The wearing rate of progressive lens was reduced in reverse proportion to the increase of the age for the people of presbyopia in a twon. Pepople in 60s living in a town perferred to wearing bifocal lens, but people of 50~60s preferred to single vision lenses. However, none of people living in a city who is diagnosed as presbyopia had refractive error correction device, and no one used bifical lenses. The progressive lens was mostly used in the people of 40~50s and using rate of those lenses reduced with the age; and single vision lens had the highest rate of in the 40~50s but no one wore it in the 70s. Conclusions: Among the refractive error correction devices, the progressive lens was most widely worn by presbyopia group who is living in a town or a city. In particular, the refractive error correction devices were most preferred in 40~50s of early presbyopia. The highest preference for the progressive lens in the people with the early presbyopia indicates that the wearing rate of the progressive will be increased in future. Therefore, the opportunity of systematic education on the progressive lens should be increased.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.2
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• pp.165-171
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• 2013

Purpose: This study are to analyze and to compare between pupillary size, reaction time, refractive error, corrected vision, dominant eye, static visual angle (SVA) and kinetic visual acuity (KVA) of male and female college students, to measure KVA of them in full correction and to identify changes of KVA by +0.50 D and -0.50 D spherical power addition respectively in full correction condition. Methods: KVA, SVA, pupillary size, reaction time, refractive error, corrected vision and dominant eye of 40 male and 40 female optical science students were measured by utilizing KOWA AS-4A, reaction time measurement program, subjective refractometer, and objective refractometer, and KVAs were measured when +0.50 D/-0.50 D were added in both eyes respectively. Results: Binocular KVA of whole subjects was $0.45{\pm}0.22$, and in monocular KVAs were $0.36{\pm}0.19$ for right eye and $0.34{\pm}0.19$ for left eye, and binocular KVA was significantly higher than monocular KVA. It appeared that the better SVA was, the better KVA was in significant way, and in terms of refractive error the less myopia amount was, the better KVA was, but it was not significant statistically. The lower astigmatism was, the slightly and significantly higher KVA was when dividing between equal or less than -1.00 D astigmatism group and over -1.00 D astigmatism group. In resulting from correction condition of refractive error KVAs were $0.45{\pm}0.22$ for full correction, $0.26{\pm}0.15$ for +0.50 D addition, $0.48{\pm}0.22$ for -0.50 D addition which indicates that KVA in over myopia correction was significantly the highest and followed by full correction and under correction. Similar findings were revealed in both male and female, and KVA of male was better than female in comparing between male and female. There was no significantly different KVA between dominant eye and non-dominant eye. Conclusions: Accordingly, it is concluded that KVA is related with far distance SVA, astigmatism amount, and refractive error amount except a dominant eye. Through this research, it was found that prescription for enhancing KVA is to make full correction or to overcorrect slightly myopia.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.3
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• pp.313-317
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• 2011

Purpose: This study was to assess prevalence of refractive errors and uncorrected refractive errors in elementary school children in Mokpo and uncorrected refractive errors were to be used as the basic data. Methods: Vision tests were conducted on 400 subjects of 1st~6th grades at 3 elementary schools in Mokpo city, and subjective, objective refraction test were also performed to survey uncorrected refractive errors. Results: The prevalence of myopia was 256, 64% of total subjects, Hyperopia was 21, 5.3%, astigmatism was 19, 4.8%. The prevalence of uncorrected refractive errors were increased as higher grade and more oculus dexter higher than oculus sinister. Conclusions: Vision impairment which need an accurate vision correction for elementary school students requires the regular examination and actively correction in order to protect the elementary school students for basic welfare.

• Korean Journal of Remote Sensing
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• v.28 no.2
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• pp.237-243
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• 2012

In this paper, an atmospheric effect of repetitive measurements of X-band (9.65 GHz) arc-rail type GB-SAR (ArcSAR) system was quantitatively analyzed. Four artificial triangular trihedral corner reflectors as stationary targets for getting stable back scattered signal during 43 hours continually. The results of the analysis showed that the phase of those stationary targets had changed maximum of 5 radian (12.4 mm) and total RMS error had was 1.62 radian (4 mm) during 65 repeated measuring time. The refractive index of air which was calculated using the temperature;humidity and pressure of atmosphere showed very close relationship with the phase difference. We could check the atmospheric correction was fulfilled by the correction of an atmospheric effect using refractive index during the selected 16 hours period showed that RMS error was dropped from 1.74 radian (4.3 mm) to 0.10 radian (0.24 mm).

• Current Optics and Photonics
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• v.3 no.1
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• pp.72-77
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• 2019

This study was performed to analyze the optical aberrations of the cornea induced by myopic refractive surgery. Corneal total higher-order aberrations, spherical aberration and coma for 4-mm and 6-mm pupils were measured using a wave-front analyzer. The amount of aberrations of the oblate corneal optics by the achieved correction was found to be larger than for the prolate corneal shape with complete eye, in an emmetropia control group. The change in corneal shape acts as an optical factor that degrades the quality of the retinal image; it seems to be one of the important factors related to quality of vision.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.1
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• pp.139-146
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• 2000

Once refractive error of the eye was fully corrected, Maddox rod was used to investigate binocular vision function. When the deviations of subjects' eyes were measured, orthophoria. without any horizontal deviations, was found in 10%, esophoria in 55% and exophoria in 34% of the patients. Esodeviation of the eye was found to be greater than exo-deviation by 11%. This is also refracted in deviations found to be greater than $4{\Delta}$ diopter magnitude where esophoria was 23% and exophoria was 9%. Thus for the patients to achieve comfortable binocular vision function, binocular vision anomalies need to be considered in spectacle prescription. In examining ocular anomalies of corrected refractive error, the deviation of the eye differed from under corrected refractive power to over corrected refractive power. There was a decrease in exophoria and an increase in esophoria, with over correction. This was thought to be due to accommodation. Furthermore, calculated AC/A ratio was found to vary from 1.25 to 6.61 and its relationship to refractive error could not be determined.