• Title/Summary/Keyword: 폭주근점

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Possibility about evaluation test of Substitution of NPC Alteration for AC/A Ratio (폭주근점 변화의 AC/A비 대체 평가지표에 대한 가능성)

  • Yoo, Hyun;Lee, Eun-Hee
    • 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.

A Study About N.P.C, Heterophoria and Near Convergence and Divergence by Amount of the Refractive Errors (굴절이상도에 따른 폭주근점과 근거리 수평사위, 폭주 및 개산 여력의 연구)

  • Choi, Sun-Mi
    • Journal of Korean Ophthalmic Optics Society
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    • v.14 no.4
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    • pp.53-57
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    • 2009
  • Purpose: To study the relationship of N.P.C, heterophoria and near convergence and divergence by amount of the refractive error. Methods: All subjects have no ocular disease and their mean age is 22.7. All 39 subjects examined about refractive error, near point of convergence (NPC), heterophoria, near convergence and divergence. Results: Classified by low refractive state, middle refractive state, and high refractive state compared with the expected value of Morgan. NPC had been measured within low and middle refractive state eight all the 8cm. However, high refractive state measured 9.64 cm. Low and middle refractive state for the classification by near phoria. Near esophoria groups was smallest by near divergence and exophoria groups was smallest by near convergence. Conclusions: Near convergence were largest with esophoria while near divergence were largest with exophoria.

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Research on Visual Function Before and After Prescription of Vertical Prism (수직사위 교정 전·후 시기능 변화에 대한 연구)

  • Kim, So-ra;Lee, Gi-yung;Park, Hyun-ju
    • Journal of Korean Ophthalmic Optics Society
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    • v.20 no.2
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    • pp.229-235
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    • 2015
  • Purpose: This study was undertaken to study on visual function before and after prescription of vertical prism. Methods: 80 subjects (10-30ages) who had been precribed vertical prism and 1 year after they were represcribed vertical prism. Results: Phoria (p=0.000), supra vergence (p=0.000), NPC (p=0.003), NPA (right eye) (p=0.005), NPA(left eye) (p=0.000) showed a significant change. Conclusion: Vertical prism prescription was reduced during revisit. Supra vergence, NPC, NPA(right eye), NPA(left eye) showed a significant change. Binocular Accommodative lag was not associated with vertical prism prescription and binocular vision findings.

The Change of Near Point of Convergence and Fusional Reserves after Computer Gaming with Different Direction of Eye Movement (안구의 운동방향이 다른 컴퓨터 게임 후 폭주근점과 융합여력의 변화)

  • Kim, Se Il;Kwon, Ki-Il;Lee, Jiye;Lee, Hyo Jin;Park, Mijung;Kim, So Ra
    • Journal of Korean Ophthalmic Optics Society
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    • v.18 no.1
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    • pp.37-43
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    • 2013
  • Purpose: The present study was conducted to investigate whether the directions of eye movement in playing computer games for certain period affected the change of near point of convergence (NPC) and fusional reserve (FR) or not. Methods: Total 40 subjects in 20s who have the visual acuity of 1.0 or higher without any ocular disease and accommodative dysfunction were asked to successively play computer games. After the subjects were moving eyes in horizontal and vertical directions for 40 and 90 minutes, their horizontal fusional reserves, vertical fusional vergence and near point of convergence were measured. Results: The near point of convergence showed a tendency to be receded after computer gaming in the horizontal and vertical directions, and both of horizontal and vertical fusional reserves were significantly reduced. The range of declined fusional reserves and receded near point of convergence after computer gaming for 90 minutes was smaller than those after computer gaming for 40 minutes. The change of binocular vision was affected by the horizontal eye movement rather than the vertical movement when analyzed by the direction of eye movement. Conclusions: This study revealed that the change in FR and NPC was different along with dominant direction of eye movement during visual display terminal (VDT) tasks. Therefore, the adjustment of VDT working time is required to prevent the dysfunction of binocular vision according to the dominant direction of eye movement during VDT task.

Changes in Near Lateral Phoria and Near Point of Convergence After Viewing Smartphones (스마트폰 시청 후 나타난 근거리 사위 및 폭주근점의 변화)

  • Park, Kyung-Joo;Lee, Wook-Jin;Lee, Na-Geum;Lee, Jeong-Young;Son, Jeong-Sik;Yu, Dong-Sik
    • Journal of Korean Ophthalmic Optics Society
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    • v.17 no.2
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    • pp.171-176
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    • 2012
  • Purpose: This study was to compare changes in near lateral phoria and near point of convergence after viewing smartphones and monitors during short periods. Methods: 50 subjects with healthy eyes from 20s to 30s (mean age, $21.84{\pm}5.13$ years) were examined. Viewing time was set at 5 min to 20 min, and recovery time was 10 min. Near lateral phoria and near point of convergence (NPC) were examined before and after watching smartphones and monitors, and subjectively symptoms for visual fatigue were surveyed using a questionnaire before and after viewing image. Results: The tendency of phoria in viewing smartpones found more exophoric results than in viewing monitors, and both exophoric shifts were recovered after 10 min. The receded NPC in the smartphones was more remote than in the monitors. The smartpones induced more visual fatigue than the monitors. Conclusions: Sustained smartphone works induced changes in phoria and NPC, and this type of stress could cause visual fatigue. Therefore, an appropriate rest breaks can be helpful in relieving visual fatigue.

Measurement of Amplitude of Accommodation using Push-up and Push-away and Near Point of Convergence in Elementary School Children (초등학생에서 push-up과 push-away 방법을 이용한 조절력과 폭주 근점의 측정)

  • Kim, Hyojin;Lee, Eun-Hee;Oh, Hyunjin
    • Journal of Korean Ophthalmic Optics Society
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    • v.17 no.3
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    • pp.279-284
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    • 2012
  • Purpose: We measured the amplitude of accommodation using the push-up and push-away tests and near point of convergence (NPC) and investigated the accommodative insufficiency (AI) and convergence insufficiency (CI) in elementary school children of 12~13 years old. Methods: 88 students who aged 12~13 $12.63{\pm}0.51$ years old with more than 1.0 spectacle best corrected visual acuity were examined using push-up and push-away tests. The break and recovery points of NPC also were measured. Results: Mean amplitudes of accommodations using push-up and push-away tests were $11.52{\pm}2.50D$ and $10.06{\pm}1.97D$, respectively in right eye (P<0.001). Mean break and recovery points in NPC were $8.66{\pm}1.99cm$ and $10.98{\pm}2.06cm$. AI and CI showed 28.75% and 30.00% each. 48.75% was within normal range in both amplitudes of accommodations according to their age expected and convergence. Students having both AI and CI were 7.50%. Conclusions: A high correlation between the push-up test and push-away test was found in elementary school children (r=0.6025; P<0.05). Students having normal amplitude of accommodation by their age expected and normal convergence were 71.25% and 70.00%, respectively.

Influence of Different Diagnostic Criteria on Frequency of Convergence Insufficiency (진단기준 차이가 폭주부족의 빈도에 미치는 영향)

  • Yu, Dong-Sik;Cho, Hyun Gug;Moon, Byeong-Yeon
    • Journal of Korean Ophthalmic Optics Society
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    • v.21 no.3
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    • pp.235-242
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    • 2016
  • Purpose: This study was to investigate whether the application of different diagnostic criteria affected the frequency of convergence insufficiency (CI). Methods: Eighty one subjects with mean age of 22.54 years (20 to 27 years) were evaluated. Binocularity tests after refraction were performed as the following tests: near point of convergence (NPC) with an accommodative target, phoria using von Graefe method, positive fusional vergence (PFV) with a phoropter. Subjects with CI were diagnosed when exophoria (exo) was greater at near than at distance ($exo{\geq}4{\Delta}$, or >$6{\Delta}$), fusional vergence was $PFV{\leq}11{\Delta}$ for blur, $PFV{\leq}15{\Delta}$ for break, Sheard's or Percival's criterion, and NPC was $NPC{\geq}6cm$, ${\geq}7.5cm$ or >10 cm. Results: Frequency of CI with one diagnostic criterion was ranged from 6.2% to 77.8%, and was overestimated or underestimated according to criteria. It was reduced to the range of 6.2% to 43.2% with diagnostic criteria more than two, especially to the range of 24.7% to 28.4% with lower variability in diagnostic criteria including phoria and Sheard's criterion. There were high relationship between total score of signs and phoria score (r = 0.772, p<0.001), and measured phoria and Sheard's criterion (r = -0.654, p<0.001), but NPC had a high variability and a weak or no significant relationship with other diagnostic criteria. Results suggested $exo{\geq}4{\Delta}$, Sheard's criterion and $NPC{\geq}7.5cm$ for diagnostic criteria of signs and sequence for CI. Conclusions: Frequency of CI is likely to be over- and underestimated with diagnostic criteria. Cutoff values and procedures for phoria, Sheard's criterion and NPC as clinical signs should be suggested definitely in diagnosis associated with CI.

Time-dependent Changes of Ocular Functions after Alcohol Ingestion (알코올 섭취 후 시간경과에 따른 시 기능의 변화)

  • Kim, Sang-Yoeb;Moon, Byeong-Yeon;Lee, Sun Haeng;Cho, Hyun Gug
    • Journal of Korean Ophthalmic Optics Society
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    • v.14 no.1
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    • pp.133-138
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    • 2009
  • Purpose: This study was designed to investigate the changes of vision and ocular functions induced by increase of blood alcohol level. Methods: Blood alcohol level, vision, refractive errors, near point convergence, heterophoria, and relative convergence were measured at 1 h, 4 h, and 24 h after acute alcohol ingestion of 0.7 g per kg body weight. Results: At 1 h after alcohol ingestion, myopization and ocular functions which measured near point convergence, positive and negative convergences, and degree of heterophoria remarkedly worked a changes accompanied with the maximum value of blood alcohol level. But at 24 h after that, all of ocular functions were recovered to degree of 90~99% compared with non-alcoholic normal conditions. Conclusions: As the increase of blood alcohol level is able to induce the significant changes of visual acuity and ocular functions, opticians have to understand thoroughly the patient's conditions by alcohol ingestion before refractive test and ocular examinations.

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linical Performance Analysis of Lens for Improving VDT Syndrome (VDT 증후군 개선을 위한 렌즈의 임상성능 분석)

  • Ryu, Geun-Chang;Park, Ji-Hoon;Jun, Jin;Jin Moon-Seog;Chae, Soo-Chul
    • Journal of Korean Ophthalmic Optics Society
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    • v.14 no.4
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    • pp.45-51
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    • 2009
  • Purpose: The purpose of this study is to compare and analyze the survey results of clinical performance and visual problem, and the survey were carried out before and after of VDT working for 4 hours by wearing functional lens designed for improving VDT syndrome and single-vision lens. Methods: We tested near & far visual acuity, change of spherical equivalent, near point of accommodation, near point of convergence, AC/A ratio, accommodative facility and survey of subjective symptoms to visual problem of before and after VDT working for 4 hours after wearing single-vision lens and functional lens subjected on 30 males and females in the age of 20 to 45. Results: When wearing functional lens comparing to single-vision lens, near visual acuity, near point of accommodation, near point of convergence, and accommodative facility are significantly improved. It is investigated that average scores of 10 items to visual problem after VDT working for 4 hours are 3.63${\pm}$0.75 at single-vision lens and 4.69 ${\pm}$ 0.83 at functional lens, and therefore functional lens is significantly improved. Conclusions: It is thought that functional lens is an excellent lens which helps to improve accommodative function and visual problem after VDT working for 4 hours than single-vision lens.

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Comparison of Binocular Function in Normal Subjects and Convergence Insufficiency (정상안과 폭주부족안의 양안시기능 검사값 비교)

  • Shim, Hyun-Seog;Shim, Moon-Sik;Kim, Sang-Hyun
    • Journal of Korean Ophthalmic Optics Society
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    • v.15 no.3
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    • pp.287-291
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    • 2010
  • Purpose: The aim of this study was to compare binocular functions such as near point of convergence (NPC), AC/A ratios, heterophoria, accommodation, accommodation lag, positive relative accommodation (PRA), negative relative accommodation (NRA), positive relative convergence (PRC), negative relative convergence (NRC) in normal subjects and convergence insufficiency. Methods: 86 subject (male n=45, female n=41, mean $age{\pm}SD=23.27{\pm}2.85$ years) without amblyopia, strabismus, and ocular pathology were studied. Forty three patients each group were classified as normal subjects and convergence insufficiency group based on AC/A ratio and far and near phoria. Binocular function of the two groups was measured using phoropter. r. Results: The values between normal subjects and convergence insufficiency were 5.71 cm and 7.07 cm for NPC, 5.28 and 2.81 for Heterophria AC/A, 0.92 exo/3.36 exo and 2.17 exo/10.84 exo for far and near phoria, 15.49/23.30/13.30 and 13.50/20.02/9.09 for PRC, respectively. However, there were no significant differences between normal subjects and convergence insufficiency for accommodative amplitude, accommodative lag, PRA, NRA, BI vergence test, BO vergence test, NRC. Conclusions: Both groups were a significant difference for cover test, NPC, Heterophria AC/A, far and near phoria, break point of PRC, and recovery point of PRC.