• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.67-71
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• 2002

To investigate the ametropia and refractive error of 364 ametropic eyes en the 182 high school students in Jeonbuk provicne, the visual acuity test was performed by the object and subject method. The results were as follows. 1. The eye types were 85.7% positive for myopia, 6.6% for emmetropia and 7.6% hyperopia, respectively. 2. The abnormal refraction eyes were 30.8% positive for simple myopia, 58.5% for myopia compound astigmatism, 7.5% for myopia simple astigmatism, and 1.8% for simple hyperopia, 1.3% for hyperopia compound astigmatism, 1.9% for hyperopia simple astigmatism, respectively. 3. The axes of astigmatism were 78.7% for astigmatism with-the-rule, 13.9% for astigmatism against-the-rule, 7.4% for astigmatism oblique, respectively. 4. As for the astigmatic power, the 0.50 < cylinder < 1.00dptr was 60.0%, the 1.00 < cylinder < 2.00dptr was 29.2%, and anything over the 2.00cylinder dptr was 10.8%. 5. As for the equivalent spheric power of myopic abnormal refraction eyes, the -0.50 < spheric equivalent < -2.00 diopter was 64.6%, the -2.00 < spheric equivalent < -6.00 dptr was 29.1% and anything over the -6.00 dptr was 6%. 6. The equivalent spheric power of hyperopic abnormal refraction eyes was 50% anything under 2.00diopter and 50% for anything over the 2.00diopter.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.2
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• pp.131-135
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• 2006

The purposes of this study is examining a wearing tendency of a progressive multifocal lens. We measured refractive error values using subjective and objective refraction method with subjects in 40-65 ages. Also, we investigated and analyzed distribution of addition power and wearing tendency of progressive multifocal lens. Detected addition powers were ranged of +0.75D - +3.00D. In case of average addition, they were detected with +1.18D in 40's, +1.55D - +1.97D in 50's and +2.38D in above 61's age. The distributions of visual ability at a distant were measured that the hyperopia and hyperopic astigmatism 43%, the myopia and myopic astigmatism characteristic astigmatism 7% appeared highly with 36%. The male who uses the interior aspect multi focal lens with the short-range work were appeared the male 20%, the woman 19%.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.2
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• pp.251-255
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• 2004

Our research is about the measurement of the distance & near horizontal phoria by the Von Graefe test. The inspection was processed about normal 60 subjects(120eyes) aged from 20 to 30) years old by the subjective method of refraction. Among 120 eyes, the myopia is 64eyes(53%) and the emmetropia is 56eyes(47%). In the measurement of the distance horizontal phoria, we could know that the exophoria is 40%(24 subjects), the esophoria is 40%(24 subjects), and the orthophoria is 20%(12 subjects). In case of the near horizontal phoria, we could know that the exophoria is 65%(39 subjects), the esophoria is 23.3%(14 subjects), and the orthophoria is 11.7%(7 subjects).

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.4
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• pp.55-69
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• 2007

The purpose of this study was to perform a clinical test using ez NANOsence II RGP contact lenses for the effects of visual acuity and cornea on subjects with abnormal refraction status. One hundred twenty one adults (twenty nine males, ninety two females, range = 17 to 43, mean = 22.86) were recorded. The subject's history including, the symptoms from previous lens wear, were studied. The subjects were observed, both pre and post lens wear, for any symptoms and signs of change of the eye. The Visual acuity and the binocular status were tested at the far distance using the contact lens. The refraction test was performed on the naked eye using the objective method (Topcon KR-8100, Japan). The Stereopsis test was performed at the near distance after contact lens wear by the Titmus fly (Stereo Optical Co., U.S.A) and TNO (TECH, The netherlands). The contrast sensitivity diagnosis was performed at 1m distance after contact lens wear by the contrast sensitivity chart (pelli-Robertson, USA). The corneal topography was analyzed on the naked eye after lens wear by ORB scan (Bausch Lomb, U.S.A.). The ultra structure of surface on the contact lens was observed using SEM (JMS-5800, Japan). The chemical component's of the contact lens was analyzed by EDS program. The results of this study were as follows: 1. The longer of contact lens wear period, The subjects have acquired the most improved visual function. 2. Subjects had experienced few side effects wearing the contact lenses. 3. The lenses were easy to use by the subjects. 4. The longer of contact lens wear period, the power of cornea had more decrease. but the base curve of cornea had more increase and corneal astigmatism was decrease (p<0.01). Also, the thickness of corneal center was few decrease. 5. Longer periods of using the contact lens showed stereopsis and contrast sensitivity at more normal values. 6 The corneal topographical after lens wear showed most subjects with similar morphology for different wear periods. 7. The surface ultrastructure of the new and used contact lens was the similar fine shape. 8. The chemical component's of in the new and used contact appeared to have similar results. In conclusion, this study showed that the surface ultrastructure and chemical component's of the new and used contact lens are similar. In addition, the subjects had improved the quality of vision and few experienced any side effects during long periods of contact lens wear. Also they have decrease of corneal astigmatism during the long period of lens wear. Our test has showed that the chemical composition and fine structure of contact lens have related to the visual function on contact lens wearer. In this paper, we suggested that ez NANOsence II RGP contact lenses had a moderate effect for correcting vision of abnormal refraction eye.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.1
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• pp.79-85
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• 2014

Purpose: This study investigated accommodative changes by measuring accommodative response, appearing on the normal and convergence insufficiency Group, by using both eyes open-view auto-refractometer (Nvision-K5001, shin-nippon, Japan). Methods: It carried out objective and subjective refractions, targeting 74 college students (54 males and 20 females) aged between 19 and 29 ($21.59{\pm}2.53$), spherical equivalent OD $-2.28{\pm}2.03$ D, OS $-2.18{\pm}2.01$ D, by measuring accommodative responses at full correction and under correction with plus lens +0.25, +0.50, +0.75 arbitrarily added. Results: In the group of normal and convergence insufficiency, the shorter fixation distances were, the greater accommodative lags showed. The group of convergence insufficiency showed the lesser changes of accommodative response than those of normal. But we found that the convergence insufficiency group had a little larger accommodative amplitude in the total fixation distances. The full correction of convergence insufficiency group and the under correction (+0.50 D) of normal were alike in the accommodative responses. We have also investigated that the correlation between accommodative responses and fixation distances was decreased steeply at the excessive low vision correction. Conclusions: Under correction (+0.50 D) in a near distance is expected to avoid unnecessary accommodative responses, make eyes relaxed and comfortable.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.2
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• pp.79-85
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• 2000

This study was investigated the refractive state and the analysis of ametropic frequency among schoolchildren who were the three grade in W elementary school in Suwon. Total 488eye (244 persons) were examined by the trial-lens set and the questionary. Through Trial-Lens set verification, several factors related to ametropic frequency were obtained as the following. Among the 244 persons, the students who wear spectacles or need to wear spectacles were 27.3%, among the 27.3% students, the students who have low visual acuity below 0.3 were 6.3%. The ametropia eyes among the total eyes were 27.3%. Among ametropic eyes, myopia and hyperopia were 25.4% and 1.9%. Among the total ametropic errors were low refractive error were 71.4%, and middle refractive error were 28.6%. In ratio myopic frequency, it was statistically related to the refractive errors with the environments factors such as reading distance & habits, T.V watching distance. Among the students belonged to below 0.7 visual acuity, the wear spectacles students were 63.3%. The ratio of anisometropia was 3.4%.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.2
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• pp.137-142
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• 2013

Purpose: This study was designed to investigate the current status of visual acuity for elementary school students in Muan-gun and to analyze improvements of their visual function after vision training for the elementary school students who have either insufficiency of accommodation or vergence. Methods: Subjective refraction, objective refraction and binocular function were examined for 335 elementary school children from year 1 to year 6 live in Muan area, and then 47 students who have symptoms of binocular dysfunction among them were selected. We analyzed and compared between before and after vision training (VT) in binocular vision function results. Results: The results show that most of the subjects had much problem in near point convergence (NPC) than accommodation. After the vision training, the average of subjects NPC was improved about 5.93 cm, from $11.57 {\pm}1.850$ cm for before VT to $5.66{\pm}0.965$ cm for after VT. After VT positive fusional vergence at near distance after VT was $19.64{\pm}3.66$ $\Delta$, which was as much as double of near phoria. Accommodative amplitude was improved from $10.02{\pm}2.566$ D for before VT to $12.30{\pm}1.397$ D for after VT, which similar to mean of expected accommodative amplitude of 11.27 years old. Conclusions: Among insufficiency of accommodation and vergence NPC was improved specially, and accommodative facility and other ocular functions were also improved. Therefore, it is considered the vision training is very effective to recover from visual function problems.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.4
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• pp.417-423
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• 2011

Purpose: This study was to investigate that near gradient AC/A ratio could be used to prescribe a patient with distance exophoria, we compared the difference between distance gradient AC/A ratio and near gradient AC/A ratio. Also, this thesis was to understand the relationship between calculated AC/A ratio and gradient AC/A ratio. Methods: Objective and subjective refractive error were corrected and we used Howell (3 m) chart for distance phoria tests and Howell-Kim (40 cm) chart for near phoria tests. The near gradient AC/A ratio and calculated AC/A ratio were used by Howell-Kim (40 cm) combined with +1.00 D, -1.00 D, +2.00 D and -2.00 D. Results: The average value of distance exophoria was 1.17${\pm}$1.17 $\Delta$, and the average value of near exophoria was 3.71${\pm}$2.80 $\Delta$ (t-test. p<0.001). The correlation of distance phoria with near phoria was little higher (r = 0.59, p < 0.001). Gradient AC/A ratios depending on measuring distance and stimulus were higher (r = 0.11~0.53. P < 0.001), when distance was shorter and stimulus to accommodation was more. Also, stimulus to accommodation by plus lens was higher than stimulus to accommodation by minus lens (paired t-test. p < 0.001). There was negative correlation between calculated AC/A ratio and gradient AC/A ratio. As the calculated AC/A ratio was higher, gradient AC/A ratio was lesser. Near gradient AC/A ratio was slightly higher than distance gradient AC/A ratio. Distance and near gradient AC/A ratio taken through the subjective -1.00 D were 1.30 $\Delta$/D and 1.68 $\Delta$/D(t-test. t=1.67, p < 0.001). Conclusions: There is negative correlation between calculated AC/A ratio and gradient AC/A ratio. Also, there is subtle difference between near gradient AC/A ratio and distance gradient AC/A ratio. Therefore, we need to measure distance gradient AC/A ratio when a practitioner prescribe glasses for a patient with distance exophoria.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.1
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• pp.75-81
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• 2012

Purpose: The study tried to figure out accommodative changes by measuring accommodative response, appearing on the full vision correction and low vision correction, with both eyes open-view auto-refractometer (Nvision-K5001, Shin-nippon, Japan). Methods: It carried out objective and subjective refractions, targeting 79 college students (58 males and 21 females) aged between 20 and 30($21.14{\pm}2.00$), by measuring accommodative changes with fixation distance at 1.0 m for eyesight of 1.0 after full version correction. The distances of 5.0 m, 1.0 m, 0.50 m, 0.33 m and 0.25 m for eyesight of 0.8, 0.7 and 0.6 after low vision correction arbitrarily added plus lens were applied. Results: the shorter measure fixation distances were, the greater changes accommodative response showed a tendency in the state of both full vision correction and low vision correction(0.7). The state of full vision correction showed a greater change of accommodative response than that of low vision correction(0.7). Both right and left eyes showed low accommodative responses in the state of low vision correction(0.7) than that of full vision correction. As a result of analyzing accommodative response at an eyesight of 0.8, 0.7, and 0.6 after low vision correction, the poorer eyesight was the lower accommodative response. Conclusions: Low vision correction from a near distance is expected to avoid unnecessary accommodative response, make eyes relaxed and prevent accommodative function disorder.

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.2
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• pp.13-18
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• 2003

We did the comparison research about three different methods of measuring horizontal phoria and vertical phoria which are Von Graefe test, Maddox Rod test and polarizing lens test. The inspection was don with the subjective method of refraction about normal 63 subjects aged from 20 to 28 years old. The analysis of date resulted in as follows : 1. Using Von Graefe Horizontal phoria Measurement, they were measured 5% for orthpharia, 51% for exophoria and 44% for esophoria. 2. Using Von Graefe vertical phoria Measurement, they were measured 68% for orthphoria, 20% for left hypophoria against the right and 12% for left hyperphoria against the right. 3. Using Maddox Rod Horizontal phoria Measurement, they were measured 7% for orthphoria, 49% for exophoria and 44% for esophoria. 4. Using Maddox Rod vertical phoria Measurement, they were measured 70% for orthphoria, 19% for left hypophoria against the right and 11% for left hyperphoria against the right. 5. Using Polarizing Horizontal phoria Measurement, they were measured 10% for orthphoria, 49% for exophoria and 41% for esophoria. 6. Using Polarizing vertical phoria Measurement, they were measured 92% for orthpharia, 5% for left hypophoria against the right and 3% for left hyperphoria against the right.