• Journal of Korean Ophthalmic Optics Society
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• v.13 no.4
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• pp.127-134
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• 2008

Purpose: The purpose of this study was to determine the expected values of accommodation and vergence system for analysis of binocular vision. Methods: Seventy three healty subjects without past history of eye disease were selected for this study, Patients showing clinical binocular anomalies including manifest squint and intermittent heterotropia were excluded and data was collected on 54 patients(mean age, 25.3${\pm}$2.7 year). Near point of convergence, distance and near phoiras were measured based on objective deviation angle. And then AC/ A ratio, relative accommodation were measured and all of the data were compared with the Morgan's expected values. Results: The values of distance and near heterophoria were 1.24${\pm}$2.72${\Delta}$ and 2.70${\pm}$4.91${\Delta}$ respectively and the gradient AC/A ratio was 3.92${\pm}$2.17${\Delta}$/D which were all about the same compared with the Morgan's expected values. The values of distance negative fusional convergence was same, however, distance positive fusional convergence was 7${\Delta}$ greater than the Morgan's one. There were no significant differences in the range values of both near vergences while the range of distance vergence was relatively larger than the Morgan's one. Positive relative accommodation was +0.37D greater and negative relative accommodation was -0.63D greater than the Morgan's values. Conclusions: The findings in this study appear that the Morgan's expected values have a possibilities of including considerable proximal convergence value. In comparison with Morgan's values, Korean's normal expected values have much different values of especially BO limit, so if the Morgan's values are directly applied to binocular vision analysis for Korean people, it may lead to an inaccurate binocular vision diagnosis. This results can be used to diagnose the accommodation and vergence system of Korean normal young adults.

• 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.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.