• Journal of Korean Ophthalmic Optics Society
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• v.18 no.2
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• pp.117-123
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• 2013

Purpose: The aim of this study was to propose effective data for the clinical examinations of binocular vision by comparative analysis of measuring the near horizontal phoria according to accommodative stimulations. Methods: It carried out near horizontal phorias, targeting 104 college students (50 males and 54 females) aged between 19 and 24 ($20.27{\pm}1.31$). It made a comparative analysis of changes in near horizontal phoria according to accommodative stimulations by using the von Graefe, Maddox rod and the Howell phoria methods respectively. We have also investigated the AC/A ratio in all phoria groups. Results: As the additional lenses were changed to the negative (-) diopter, the near horizontal phoria changed to the esodeviation. At this time, the rate of change in the section signifies the AC/A ratio, and the values were not consistent based on the evaluating methods or on each section. The AC/A ratio of the esophoria group appeared the largest value in all groups. As a result of analyzing AC/A ratio at the exophoria group using the von Graefe method, the AC/A ratio was $1.568{\pm}1.937$ ${\Delta}/D$ on the additional lenses +2.00 D and $2.527{\pm}2.253$ ${\Delta}/D$ on the additional lenses -1.00 D and at the esophoria group using the Howell phoria method, the AC/A ratio was $5.521{\pm}1.337$ ${\Delta}/D$, $5.593{\pm}1.623$ ${\Delta}/D$ on the additional lenses +2.00 D, +1.00 D and $4.687{\pm}1.643$ ${\Delta}/D$ on the additional lenses -2.00 D. These were significant differences statistically. Conclusions: In the exophoria group, when the (-) lenses were added, the averages of the AC/A ratio were shown to be high but in the esophoria group, when the (+) lenses were added, the of AC/A ratio was high.

• Journal of Korean Ophthalmic Optics Society
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• v.21 no.1
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• pp.53-59
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• 2016

Purpose: To investigate an individual phoria compensating effect by measuring the lens adaptation after wearing horizontal prism or spherical lenses at near. Methods: 103 subjects (63 males and 40 females) aged $22.43{\pm}2.07years$ participated for this study. Refractive errors of subjects were fully corrected, and subjects were classified into three groups; esophoria, orthophoria and exophoria. The adaptation test of prism and spherical lenses was performed immediately, 15 minutes and 30 minutes after wearing lenses with $OU\;2\;{\Delta}\;BO$ and S+1.00 D for an esophoria group and $OU\;2\;{\Delta}\;BI$ and S-1.00 D for orthophoria and exophoria groups, respectively. Each measured phoria was compared to phoria measured with fully corrected condition, and the phoria changing effects about both lenses was analyzed. Results: The mean of phoria by prism lenses significantly decreased for every group. The mean of phoria by spherical lenses also significantly decreased in orthophoria and exophoria groups. The esophoria group showed a decreasing tendency but has no significance. The decreased phoria value by prism lens was classified into three steps; 90~100%, 0~10% and 50% or more. According to results of individual distribution ratio, it was 5, 64 and 24 subjects at 30 minutes after wearing lenses, respectively. The decreased phoria value by spherical lens was classified into three steps; 90~100%, 0~10% and 50% or more. According to results of individual distribution ratio, it was 37, 53 and 41 subjects at 30 minutes after wearing lenses, respectively. The subjects having no phoria changed by both prism and spherical lenses were 37.9%. Conclusions: When prescribing to compensate the near horizontal phoria using prism or spherical lens, the pretest for lens adaptation should be taken before prescription.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.3
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• pp.269-274
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• 2010

Purpose: The repeatability of a new Red-Blue phoria chart test (Red-Blue phoria chart; RBP) was appreciated. Methods: Distance (5 m) and near (40 cm) heterophoria was measured in 38 visually normal subjects. Phoria tests using RBP, Howell phoria card (HP), and MIM card (MIM) were done and the repeatability of each phoria test was compared with one another. Results: The mean of horizontal deviations was that RBP was $-0.602{\pm}0.727{\Delta}$, HP was $-0.865{\pm}1.051{\Delta}$, and MIM was $-1.501{\pm}1.346{\Delta}$, at distance, and that RBP was $-2.566{\pm}2.352{\Delta}$, HP was $-2.804{\pm}2.411{\Delta}$, MIM was $-3.838{\pm}2.603{\Delta}$, at near. The repeatability was RBP>MIM>HP in distance tests and MIM>RBP>HP in near tests. Conclusions:RBP test is identified as a reliable phoria test having high repeatability.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.4
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• pp.329-335
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• 2006

The aim of this study was to evaluate the relation between Asthenopia of near lateral phoria and fusional reserve and also to provide fundamental clinical data. A total of 97 subjects, aged between 17 and 35 years old, who had no strabismus, an eye trouble or whole body disease, were examined nacked visual acuity, corrected visual acuity, corrected diopter, phoria, fusional reserve tests from October of 2005 to July of 2006. We excluded 8 subjects for the following reasons: if they had an amblyopia affecting binocular vision or inaccurate data. After these exclusions, 87 subjects remained. The results were as follow. According to interview results was that in near works, exophoria and esophoria with asthenopia was 59.6%, 64.7%, and 52.6% respectively. The subjects who have exophoria of $0-6{\Delta}$ in the range of normal state was 19.1%. The subjects who have exophoria of $7{\Delta}$ over in the range of abnormal state was 80.9%. The fusional reserve was in inverse proportion to phoria. The fusional reserve was twice over of phoria were 30.3%, and twice under were 69.7%. The asthenopia complain persons were 33.9% with the twice over fusional reserve of phoria. The asthenopia no complain persons were 66.1% with the twice under fusional reserve of phoria. In conclusion, our research has shown conclusively that there is a link between asthenopia of lateral phoria and fusional reserve and we also find that fusional reserve must be examined when we prescribe for a patient who has phoria.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.3
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• pp.159-164
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• 2005

Accommodation and convergence is combination movement which is closely connected with each other. When one of them is stimulated, both of functions occur at the same time. Specially, the convergence by the accommodation's stimulation is called as accommodative convergence. That has excess or deficiency according to refraction state of eye. This study was performed by using both of Gradient method and Heterophoria method to 41 adults who have no any ophthalmic disease. 1. As the result of investigation about the distribution of heterophoria at distance, there were orthophoria of 5 subjects, exophoria of 32 and esophoria of 4. Exoporia occupied at the hightest rate. The distribution of heterophoria at near cover a wider range more than at distance. 2. When we measured the horizontal heterophoria amount in the state of relaxation of accommodation power of lens, exophoria amount increased in case of 38 subjects. 3. The person who has $4{\sim}6{\Delta}/D$ which conform to normal AC/A ratio occupied 27 subjects(66%) in Heterophoria method and 16(39%) in Gradient method, respectively.

• Journal of Digital Convergence
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• v.11 no.11
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• pp.661-666
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• 2013

The aim of this study was to evaluate the property of heterophoria and fusional reserve in Adults in Jeon-buk Area. We examined the corrected visual acuity, corrected refractive error, heterophoria and fusional reserve of 116 healthy myopes aged from 20 to 44 old who had no strabismus no ocular and phyisical diseases. Using Von Graefe test of horizontal heterophoria Measurement, we measured orthophoria(26.7%), exophoria(52.5%) and esophoria(20.7%) for at near distance. The subjects who had exophoria of 0-6${\Delta}$ in the range of normal state was 38.8%, while the subjects who had exophoria in the range of abnormal state was 61.2%. Reducing fusional reserve was associated with increasing phoria. We found a relationship between asthenopia and fusional reserve of heterophoria and considered that fusional reserve must be examined when we preserve for a patient with heterophoria. Furthermore, Gradient method AC/A ratio was found 4.03 and its relationship to refractive error could not be determined.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.2
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• pp.195-200
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• 2015

Purpose: This study was performed in order to figure out the influence of illumination on visual function. Methods: 40 adults (male 21, female 19) of average age $23.93{\pm}1.59$ years were participated in this study. The test chart surface illumination was adjusted to 5, 50, 200, 500 and 800 lx, and then amplitude of accommodation, near point of convergence, far and near distance phoria, far and near distance fusional vergence, relative accommodation, and accommodation lag were measured at each illumination condition. Results: As illumination intensity of test chart was reduced, amplitude of accommodation was significantly decreased (p<0.05), accommodation lag was also decreased, near point of convergence was receded, and horizontal phoria showed a tendency of esodeviation. In the case of negative fusional vergence, with reduction of illumination intensity, the break point and the recovery point were decreased but in the case of positive fusional vergence, the break point was increased. The negative and positive relative accommodation were significantly decreased (p<0.05) with reduction of illumination intensity. Conclusions: In clinical practice, visual functional test should be performed under condition of adequate illumination level through patient's living environment and job.

• 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.