• Journal of Korean Ophthalmic Optics Society
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• v.19 no.4
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• pp.551-555
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• 2014

Purpose: This study is to investigate if the improvement of visual sensory (VS) by amblyopia treatment affects the ocular functions in refractive errors, accommodative errors and phoria at distance and near. Methods: 10 subjects (17 eyes, mean age of $10.7{\pm}2.9$ years) who treated amblyopia completely, were participated for this study. Refractive errors, accommodative errors, and distance and near phoria were compared between before and after treatments of amblyopia. Refractive errors and accommodative errors at 40 cm were measured using openfield auto-refractor (NVision-5001, Shin Nippon, Japan) and using monocular estimated method (MEM) respectively. Phoria was determined at 3 m for distance and at 40 cm for near using Howell phoria card, cover test or Maddox rod. Results: Mean corrected visual acuity (CVA) significantly increased from $0.46{\pm}0.11$ (decimal notation) for before amblyopia treatment to a level of $1.03{\pm}0.13$ for after amblyopia treatment (p < 0.001). For spherical refractive error, hyperopia significantly decreased from $+2.29{\pm}0.86D$ to a level of $+1.1{\pm}2.38D$ (p < 0.05) but astigmatism did not significantly change; $-1.80{\pm}1.41D$ for before treatment and $-1.65{\pm}1.30D$D for after treatment (p > 0.05). Accommodative error significantly decreased from accommodative lag of $+1.1{\pm}0.75D$ to a level of $+0.5{\pm}0.59D$ (accommodative lag) (p < 0.05). Distance phoria significantly changed from eso $2.9{\pm}6.17PD$ (prism diopters) to a level of eso $0.2{\pm}3.49PD$ (p < 0.05), and near phoria also significantly changed from eso $0.4{\pm}2.32PD$ to level of exo $2{\pm}4.9PD$ (p < 0.05). There was a high correlation (r = 0.88, p < 0.001) between improvement of visual acuity and decrease of accommodative lag. Conclusions: Hyperopic refractive error decreased with improvement of CVA or VS by amblyopia treatment. And the improvement of VS by amblyopia treatment also improved accommodative error, and changed phoria coupled with accommodation.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.3
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• pp.341-346
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• 2013

Purpose: The purpose of this study was to evaluate whether a relationship exists between head posture and phoria, and usefulness in examining habitual head posture. Methods: Twenty two subjects (20 males and 2 females, mean age $23.6{\pm}2.7$ years) with abnormal phoria from participants randomized were enrolled in this study. For all subjects, testing included case history, cover test, refraction, phoria and vergence test. Habitual head posture (head posture, head tilt and face turn) was measured by Impression IST, and observed by examiners. Results: The abnormal head posture was revealed in some subjects with abnormal phoria. Spearman' correlation ($\rho$=0.524, p=0.045) showed significant correction between face turn and phoria at distance in 15 subjects with prism prescription. No significant relationship between head posture and phoria was found in subjects with abnormal phoria. The objective measurement and subjective observation of head posture showed insignificant correction but there was a distinct difference. The former was detail and the latter was discriminate. Conclusions: Presence of abnormal head posture was found in phoric subjects. The results indicate the need to observe habitual head posture at all major positions of gaze in phoria.

• 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.20 no.3
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• pp.319-324
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• 2015

Purpose: This study was designed to evaluate the changes of phoria and calculated AC/A ratio, and their recovery time points by watching 3D television (3D TV). Methods: 50 subjects (male 30, female 20) of 20s to 40s ages who can watch 3D, were measured phoria using a Howell phoria card at 3 m for distance and 40 cm for near. The phoria was evaluated before watching 3D TV and every 10 minutes from starting of watching 3D TV for 30 minutes, and every 5 minutes after finishing of watching 3D TV for 30 minutes again. Results: For the distance phoria during and after watching 3D TV, it was increased to more exophoria $-0.98{\pm}1.37{\Delta}$ (prism diopters) after 10 minutes from starting of 3D TV watching (p=0.063) and increased to more exophoria $-1.00{\pm}1.28{\Delta}$ after 30 minutes (p=0.024), and started to decrease after finishing of watching 3D TV and recovered to the level of before 3D TV watching ($-0.78{\pm}1.11{\Delta}$) after 20 minutes (p=0.32) with comparing to phoria of before watching 3D TV ($-0.80{\pm}1.12{\Delta}$). For the near phoria, it was also increased to more exophoria $-5.71{\pm}4.45{\Delta}$ after 10 minutes from starting of watching 3D TV (p=0.000) and $-6.58{\pm}4.36{\Delta}$ after 30 minutes (p=0.000), and started to decrease after finishing of watching 3D TV and recovered to the level of before watching 3D TV after 20 minutes ($-4.34{\pm}3.67{\Delta}$) (p=0.32) with comparing to the phoria of before watching 3D TV ($-4.36{\pm}3.66{\Delta}$). AC/A ratio was decreased from $4.92{\pm}1.17{\Delta}/D$ for before 3D TV watching to $4.11{\pm}1.50{\Delta}/D$ for after 30 minutes from starting of watching 3D TV (p=0.000), and increased after the end of watching 3D TV and recovered to the level of before 3D TV watching ($4.93{\pm}1.18{\Delta}/D$) after 25 minutes (p=0.598). Conclusions: During watching 3D TV at near, it showed a tendency of convergence insufficiency by decrease of calculated AC/A ratio as result that exophoria at near was higher increased than exophoria at distance. However, the increased exophoria at both near and distance was recovered to the level of base line after 25 minutes from the end of watching 3D TV. Through this study, it seems to need rational proposals of advice for watching 3D TV.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.3
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• pp.339-343
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• 2011

Purpose: In this study, we investigated changes of phoria based on varying the color and concentration of the color in lenses. Methods: We measured distance phoria for 39 students who aged 20 to 40 with different concentrated lenes - red, gray, brown and green lenses in concentration 20%, 50% and 80%, respectively. Results: Subjects were divided into three groups which were orthophoria, esophoria and exophoria. Orthophoria in all the color and concentration, there were a few of the esophoria. Esophoria of average 2.07${\Delta}$,B.O showed that a slight increase in all colors and concentration, especially in brown lenses showed the greatest increase. Exophoria of average 3.82${\Delta}$,B.I showed that a slight decrease in all colors and concentration, especially in green lenses showed to 2.95${\Delta}$,B.I to the greatest decrease. Different concentration in same color had no specific tendency regarding phoria. Conclusions: The phoria must be considered when selecting color of the lens because of phoria is changeable by color of the lens. It is expected to study the criteria that minimize the asthenopia.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.3
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• pp.363-369
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• 2014

Purpose: Three-dimensional (3D) displays are very useful in many fields, but induce physical discomforts in some people. This study is to assess symptom type and severity of asthenopia with their habitual distance corrective spectacle (HDCS) and their binocular vision corrective spectacle lenses (BVCSL) in people who feel physical discomforts. Methods: 35 adult subjects (ages $32.2{\pm}4.4$ yrs) were pre-screened out of 98 individuals to have the highest symptom/asthenopia scores following 65 minutes of 3D television viewing with HDCS. These 35 individuals were then retested symptom/asthenopia scores during they watched 3D television for 65 minutes at a distance of 2.7 m with wearing BVCSL of horizontal, vertical or base down yoked prisms. A 4-point symptom-rating scale questionnaire (0=no symptom and 3=severe) was used to assess 11 symptoms (e.g., blur, diplopia, etc.) related to visual fatigue/visual discomfort. Distance and near lateral phoria were measured using Howell phoria card and vertical phoria were measured using Maddox rod. Symptoms induced by watching 3D TV were compared between wearing HDCS and BVCSL. Results: Asthenopia in watching 3D TV with wearing BVCS was significantly lower than wearing HDCS at 5, 25, 45, and 65 minutes (all p < 0.001, paired t-tests). In only refractive error power correction power group, all asthenopia was not significantly different between HDCS and BVCSL (all $p{\geq}0.05$, paired t-tests). In prism correction groups for binocular imbalance, symptoms of asthenopia, however, was significantly lower for when wearing BVCSL than when wearing HDCS (all p < 0.05). Conclusions: Correction of phoria/vergence-based binocular vision imbalance can reduce asthenopia during 3D television viewing. An individual with binocular vision imbalance need corrected/compensated glasses with appropriate prisms prior to prolonged viewing of 3D television displays to reduce asthenopia/visual fatigue.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.2
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• pp.185-194
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• 2012

Purpose: The changes of phoria and subjective asthenopia before and after viewing were compared based on 2D image and two ways of 3D images, and presented for references of 3D image watching and production. Methods: Change in phoria was measured before and after watching 2D image, 3D-FPR and 3D-SG images for 30 minutes with a target of 41 university students at 20-30 years old (male 26, female 15). Paired t-test and Pearson correlation between changed phoria and subjective symptoms which were measured using questionnaires were evaluated by before and after watching each images. Results: Right after watching 2D image, exophoria was increased by 0.5 $\Delta$, in distance and near, but it was not a significant level. Right after watching 3D image, exophoria was increased by 1.0~1.5 $\Delta$, and 1.5~2.0 $\Delta$, in distance and near, respectively when compared with before watching. In the significant level, exophoria tended to increase. Changes in near was increased more by 0.5 $\Delta$, compared with those in distance. Changes based on way of 3D-FPR and 3D-SG image were less than 0.5 $\Delta$, and there was almost no difference. In terms of visual subjective symptoms, eye strain was increased in 3D image compared with that in 2D image. In addition, there was no difference depending on way of image. In terms of Pearson correlation between phoria change and eye strain, as exophoria was increased, eye strain was increased. Conclusions: Watching 3D image increased eye strain compared with watching 2D image, and accordingly exophoria tended to increase.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.3
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• pp.267-273
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• 2006

For this study, we measured heterophoria, Calculated AC/A, Gradient AC/A of pre & post LASIK operation. In case of heterophoria, the results showed that orthophoria 2.78% decreased, exophoria 2.78% increased on pre & post op distance phoria and exophoria 5.55% increased, esophoria 5.55% decreased on pre & post op near phoria. In case of AC/A, Calculated AC/A significantly decreased as 0.36 at AC/A and accommodation decreased as 1.25D (p<0.05). It showed that Gradient AC/A decreased 0.34 and PC/A increased 0.09 but they didn't show significant difference.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.1
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• pp.105-116
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• 2010

Purpose: To analyze and compare differences between single vision lenses and functional progressive addition lenses and improvement to binocular visual function wearing functional lenses for pre-presbyopes altered their single vision lenses to functional progressive addition lenses with low addition. Methods: Healthy 32 subjects aged 24.03${\pm}$1.87 (male 23, female 9) who were recruited from university students wore functional progressive addition lenses (EYE-T, Chemilens Co., Korea, ADD 0.750) for 2 months. Objective refraction, corrected visual acuity at distance and near, near point of convergence, near point of accommodation, accommodative facility, phoria at distance and near were measured. And subjective satisfaction was investigated by using a questionnaire designed to fatigue, comfort, discomfort, overall satisfaction and preference. Results: Functional progressive addition lenses were better than single vision lenses at near point of convergence and accommodation, accommodative facility. Exo phoria measured at distance with single vision and functional progressive addition lenses. Exo phoria measured at near with functional progressive addition lenses was higher than that with single vision lenses. As a survey, the satisfaction was increased in questions related near work. However, single vision lenses were preferred in distance test of overall satisfaction, easy 10 adapt, lime to adapt. A survey showed thai preference of functional progressive addition lenses were increased 75.00% to 81.26% for near work, 50.00% to 65.63% for visual fatigue, 47.75% to 50.00% for visual comfort and 31.25% to 46.88% for overall comfort. Conclusions: Comparing between single vision lenses and functional progressive addition lenses, binocular visual function related near work, subjective satisfaction and preference was improved after wearing functional progressive addition lenses. This study suggested that functional progressive addition lenses were useful for long time near work.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.4
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• pp.419-428
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• 2005

The aim of this study was to provide data for the relief of asthenopia during binocular vision by determining the characteristics of ocular function in adults. A total of 260 subjects were between the age of 19-35years. We measured individually the refractive error correction, pupillary distance, optical center distance, phoria, convergence, accommodation and the AC/A as well as the asthenopia during binocular vision using a questionnaire. After analysis of factors affecting asthenopia, we also examined the reductive effect of asthenopia in subjects who had asthenopia using prism. To determine the factors affecting asthenopia during binocular vision, statistic analyses were carried out the multivariate Logistic regression model. The results of this study were as follow. The asthenopia during binocular vision was found 26.9% of subjects. Multivariate logistic regression model was used to determine factors affecting binocular vision of myopia. When the accommodation and convergence were low compared to being high, when subjects had esophoria or there was more exophoria, and when AC/A was lower than the standard, the rate of asthenopia was higher. Therefore the accommodation, convergence and AC/A could be predictive factors for asthenopia. We used prism for subjects who had asthenopia during binocular vision, the results showed that the symptom of asthenopia was eased up to 74.3%.