• Journal of Korean Ophthalmic Optics Society
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• v.9 no.2
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• pp.423-430
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• 2004

This Study on three different methods which are Von Graefe test, Maddox Rod test and Howell card test of measuring far and near lateral phoria investigated. It reviewed that 420 subjects aged from 15 to 35 years old. The result were as follows; 1. Using Von Graefe lateral phoria measurement, they were measured 6% for orthophoria, 62% for exophoria, 32% for esophoria at far distance. 2. Using Von Graefe lateral phoria measurement, they were measured 2% for orthophoria, 74% for exophoria, 24% for esophoria at near distance. 3. Using Maddox Rod lateral phoria measurement, they 59% for exophoria, 37% for esophoria at far distance. 4. Using Maddox Rod lateral phoria measurement, they 67% for exophoria, 30% for esophoria at near distance. 5. Using Howell card lateral phoria measurement, they 60% for exophoria, 32% for esophoria at far distance. 6. Using Howell card lateral phoria measurement, they 69% for exophoria, 27% for esophoria at near distance.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.3
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• pp.79-87
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• 2008

Purpose: This study measured Y-intercept that means a fixation disparity, X-intercept that means a associated phoria and slope of a fixation disparity curve (FDC), which are variables of dissociated phoria and the FDC. We searched for the result value and examined the direction, distribution pattern and a variable that give an most affect on dissociated phoria and the FDC at distance and near. Also this study examined that there were statistically significant differences between distance and near, comparing the result value. Methods: We measured the dissociated phoria and the fixation disparity for 51 subjects at distance and near in June, 2007. All subjects ranged from 20 to 25 years of age (average 21.72${\pm}$1.88 years old) and had no eye disease. At distance the dissociated phoria measured with the distance MIM card (muscle imbalance measure card, Bernell co., USA), and the fixation disparity measured with the modified Mallett Far Unit (Bernell co., USA). At near the dissociated phoria measured with the near MIM card (muscle imbalance measure card, Bernell co., USA), and the fixation disparity measured with the Wesson fixation disparity card (American Optical co., USA). Results: The percentage distribution of types of fixation disparity curves was that at distance prevalence of Type I (74.6%) was the highest, followed by Type IV (17.6%) and Type II (3.9%), Type III (3.9%) and that at near prevalence of Type I (53.0%) was the highest, followed by Type III (29.4%), Type IV (13.7%) and Type II (3.9%). 2. There were significantly correlation in dissociated phoria, fixation disparity (Y-intercept) and associated phoria (X-intercept). 3. The fixation disparity at distance was most affected by associated phoria (X-intercept) (p=0.000). The distance dissociated phoria was most affected by fixation disparity (Y-intercept) (p=0.342), but the influence was weak. 4. The fixation disparity at near was most affected by associated phoria (X-intercept) (p=0.000). The near also dissociated phoria was most affected by associated phoria (X-intercept) (p=0.009). The result that compared the each variables with the same variables at distance and near had statistically significant on paired t-test for among dissociated phoria (t=7.529, p=0.000), X-intercept (t=5.860, p=0.000), the Y-intercept (t=4.640, p=0.000) but slope of the FDC did not differ significant (t=1.336 p=0.188). Conclusions: Relationship of fixation disparity and Heterophoria had close correlation at distance and near.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.101-105
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• 2008

Purpose: In this study we measured the mean value of the distance stereoacutiy for adult subjects and evaluated the variation of the distance stereoacuity according to correction of phoria using the Pola Test E-II of Carl Zeiss. Methods: We investigated the distance stereoacuity for 50 adults (male: 29, female: 21) ranging in age from 19 to 46 years using D6 Circle chart and D8 Line chart in the Pola Test E-II. Results: The mean values of the distance stereoacuity measured on the D6 Circle test and D8 Line test were 159.6 and 149.4 seconds of arc respectively. The mean variations of the distance stereoacuity according to correction of phoria in D6 Circle test were increased 43.2 seconds of arc in exophoria and 51 seconds of arc in esophoria, and those in D8 Line test were increased 42 seconds of arc in exophoria and 70.2 seconds of arc in esophoria. Conclusions: We knew from these results that the distance stereoacuity after prescription of phoria improved more esophoria than exophoria.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.2
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• pp.361-370
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• 2004

The purpose of this study was to evaluate the outcome and Factors that influence the quantity of Phoria in the low correction and perfect correction. Also the coincidence with the opticenter and the pupillary distance was a principal factor that influence the quantity of Phoria. Thereupon, this study is attributed to promote the perfect Phoria test. The subjects for this study were 120 persons(240 eye) in myopic refractive errors. ISP/WIN program was used for the data analysis. The collected data was analyzed by descriptive statistics and Spearman's correlation coefficient. The results of this study were as follows: 1. The prism pattern was difference between low correction and perfect correction in the Phoria test. The proportion of orthophoria was changed from 10.0% to 12.5%, exophoria was changed from 67.5% to 62.5%, and esophoria was changed from 22.0% to 32.5%, respectively. 2. The average of optical center distance and pupillary distance were 31.70mm and 31.49 mm, respectively. 3. Among the 120 myopic glasses wearers, the distance between optical centers was coincided with the pupillary distance in 37.5%, and discrepant in 62.5%. 4. For the patients who were coincided with the pupillary distance, the proportion of exophoria decreased 53.33%, esophoria increased 20.0%. 5. For the changing of the quantity of Phoria in the low correction, the degree of exophoria decreased 1.11 prism diopters in the perfect correction, esophoria increased 0.39 prism diopters.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.3
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• pp.193-200
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• 2006

We investigated the visual analysis of the far distance phoria for 83 subjects who have emmetropia or myopia eyes, using the graphic method, and determined new norms. We got the following results from these experiments. 1. The measured norm of far distance phoria is $1.12{\Delta}$, exophoria, the that of near distance phoria is $0.50{\Delta}$, exophoria, the that of negative relative convergence at far distance(N.R.C.) is ${\times}$/11/5, the that of positive relative convergence at far distance(P.R.C.) is 10/20/8, the that negative relative convergence at near distance(N.R.C.) is 11/21/5, the that of positive relative convergence at near(P.R.C.) is 10/20/8, the that of negative relative accommodation(N.R.A.) is +2.54D, and the that of positive relative accommodation(P.R.A.) is -2.60D, respectively. We know from theses results that the measured norms of far distancet phoria is higher than Morgan's norms, while those of near distance phoria are lower than Morgan's norms. 2. We also know from these experiments that Morgan's norms are closely related to A, B, and C groups and Morgan's criterion can more usefully apply to the visual analysis. 3. In Sheard's criterion and Percival's criterion, the prism prescription is occurred when the exophoria of the far-point phoria is over $7{\sim}9{\Delta}$, and the esophoria of that is over $4{\sim}6{\Delta}$.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.3
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• pp.313-320
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• 2013

Purpose: This study compared the quantity of phoria for distance by new method with that by existing methods. Methods: For this study, it was selected to two existing phoria measurements, von Graefe and Maddox rod. And new method named "3D polarizing phoria measurement" was designed to measure the quantity of phoria using polarizing glasses and 3D display. Unlike existing measurement using polarized lens, newly considered method measured the quantity of phoria in condition removed perfect binocular fusion using field stop on apparatus and polarized lens. For using new method for distance, it was developed a phoria test chart. It supports three kinds of phoria measurements. Subjects were 12 (male 6, female 6). They had three phoria tests (1 sets) including new method. It was considered the effect of experimental order, so we tested all cases about experimental order. The number of cases was 6 sets, and the sample size in this experiment was 72 sets. For removing binocular fusion, lighting of the laboratory that was below 10 lx and the background color of phoria test chart was dark, RGB=(20, 20, 20). Results: Subjects were sorted into three groups. Samples with exophoria and orthophoria were 30 sets each, and those with esophoria were 12 sets. The quantity of phoria measured three tests differ from each other like "newmethod < von Graefe < Maddox rod", and there were statistically significant difference each other. Conclusions: This study has great significance in the sense that new method was the measurement with naturally removing binocular fusion without dizziness during the tests.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.2
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• pp.211-218
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• 2015

Purpose: The aim of this study was to compare the differences among prism settings of the von Graefe technique for phoria measurement. Methods: Thirty eight healthy subjects (mean age $22.35{\pm}2.72years$) were tested with eye examination by interview, cover test, and refraction. Phorias were measured in a random order using four prism settings for the von Graefe method: base-in (BI) and base-up (BU), BI and base-down (BD), BU and BI, and BD and BI over the right and left eye, respectively. Results: Among the four prism settings in measurements of lateral and vertical phoria, there were not significant differences at distance, whereas there were significant at near. The reliability of near lateral phoria (ICC: 0.95) was good, but that of near vertical phoria was less reliable (ICC: 0.83). In comparisons of the paired t-test, the 95% limits of agreement, and mean difference between prism settings, BU had more useful than other prism settings at near phoria. Conclusions: Results from this study suggest that the von Graefe test with BU or BU including other setting prisms have useful methods, especially for near phoria measurements.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.1
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• pp.71-82
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• 2005

The aim of this study was to provide fundamental data for the factors influencing the asthenopia of emmetropia with phoria and alleviation of asthenopia. A total of 348 subjects, aged between 19 and 30 years old, who had no strabismus, an eye trouble or whole body disease, were examined using corrected visual acuity, corrected diopter, stereopsis and suppression tests from September of 2002 to September of 2004. We excluded 21 subjects for the following reasons: if they had an amblyopia affecting binocular vision or inaccurate data. After these exclusions, 327 subjects remained. We then individually measured 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 a prism on the asthenopia in subjects who had asthenopia. To determine the factors affecting asthenopia during binocular vision, statistic analyses were carried out using the Chi-square test and the multivariate Logistic regression model. The results of this study were as follow. For asthenopia during near binocular vision of emmetropia with phoria, in case of the lower the accommodation and convergence, a significantly higher rate of asthenopia was observed (p<0.001). When the AC/A is lower, the higher the rate of asthenopia was observed but not significantly and there was no association between phoria and asthenopia. When the multivariate logistic regression model was used to determine factors affecting binocular vision of emmetropia with phoria, in case of the lower accommodation and convergence, a significantly higher rate of asthenopia was observed. when the phoria is esophoria or higher exophoria, or when the AC/A is lower than normal, the higher the rate of asthenopia was observed but not significantly and there was no association between phoria. AC/A and asthenopia. Therefore accommodation and convergence could be predictive factors for asthenopia during near distance binocular vision. Prism was used among' subjects who had asthenopia during near distance binocular vision, the symptom of asthenopia was eased up to 74.2% in emmetropia with phoria.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.83-87
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• 2008

Purpose: This study was investigated for the effects of vision training on the phoria and positive fusion reverse (PFR) of patients with convergence insufficiency (C.I). Methods: Subjects were included 11 patients with CI of T Vision Center (5 patients with distance orthophoria, 6 patients with distance exophoria). The vision training of this study had been processed daily during an average of 2 months for each patients. Results: The result showed that after vision training, the phoria and PFR of CI patient were improved significantly than that before vision training (p<0.05) and when the groups were divided to the distance orthophoria convergence insufficiency (DOCI) group and distance exophoria convergence insufficiency (DE-CI) group, these improvements were proved similarly in the both groups. Conclusions: This study proved that vision training for patients with C.I was effective for the improvement of the phoria and PFR of these patients.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.2
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• pp.155-160
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• 2010

Purpose: The purpose of this study was to evaluate how phoria variations would vary with head positions, as well as to review the need to differentiate prism placement over either eye in a relation to the imbalance of the extraocular muscle. Methods: This study was carried out with 44 males (88 eyes) and 16 females (32 eyes) aged between 20 and 30. For all subjects, testings were performed using cover test, subjective refraction, phoria and vergence test. To analyze phoria variations comparatively for the head tilt test and the face turn test, phoria deviation were measured using the von Graefe. Results: For the phoria variation related with head tilt and face turn, a significant difference was observed in the group judged to be abnormal on the horizontal phoria of Morgan' norm (p<0.05); especially in patients who needed near prescription of Sheard's criterion, a higher variation was observed (p<0.05). The abnormal group was composed of patients who needed distance prescription of Sheard's criterion and ones who did not need the prescription, all of whom showed phoria variations, but the mean value was less than the near. Conclusions: With regard to the head tilt and face turn related phoria level, the patients who needed near horizontal prism prescription of Sheard's criterion showed a remarkably higher variation. Altogether, it is deemed to check whether extraocular muscles are ill-balanced in both eyes previously to determine the prism power on phoria level to the end that each of prism powers may be accurately determined.