• Journal of Convergence for Information Technology
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• v.8 no.6
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• pp.101-106
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• 2018

We examined refractive error, the corrected visual acuity, phoria and fusional reserve of 114 healthy myopes and hyperopia who had no strabismus, no ocular and physical diseases. We evaluated the occurrence of asthenopia according to phoria and fusional reserve. 41 out of 114 subjects which exophoria was 69% and esophoria was 5.5%, orthophoria was 26% made a complaint against asthenopia. The subjects who had exophoria of $0-6{\Delta}$ in the range of normal state was 61.4%, while the subjects who had exophoria of $7{\Delta}$ or more in the range of abnormal state was 38.6%. Reducing fusional reserve was associated with increasing phoria. The fusional reserve twice or more than phoria were 27.2%, and twice or under were 72.8%. Futhermore, AC/A ratio for heterophoria was found from 1.0 to 12.6 and its relationship to asthenopia of phoria could not be determined.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.2
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• pp.137-142
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• 2013

Purpose: This study was designed to investigate the current status of visual acuity for elementary school students in Muan-gun and to analyze improvements of their visual function after vision training for the elementary school students who have either insufficiency of accommodation or vergence. Methods: Subjective refraction, objective refraction and binocular function were examined for 335 elementary school children from year 1 to year 6 live in Muan area, and then 47 students who have symptoms of binocular dysfunction among them were selected. We analyzed and compared between before and after vision training (VT) in binocular vision function results. Results: The results show that most of the subjects had much problem in near point convergence (NPC) than accommodation. After the vision training, the average of subjects NPC was improved about 5.93 cm, from $11.57 {\pm}1.850$ cm for before VT to $5.66{\pm}0.965$ cm for after VT. After VT positive fusional vergence at near distance after VT was $19.64{\pm}3.66$ $\Delta$, which was as much as double of near phoria. Accommodative amplitude was improved from $10.02{\pm}2.566$ D for before VT to $12.30{\pm}1.397$ D for after VT, which similar to mean of expected accommodative amplitude of 11.27 years old. Conclusions: Among insufficiency of accommodation and vergence NPC was improved specially, and accommodative facility and other ocular functions were also improved. Therefore, it is considered the vision training is very effective to recover from visual function problems.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.2
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• pp.203-211
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• 2013

Purpose: When we look at the object, we used the dominant eye mainly. For this reason, a prescription of the dominant eye is an important factor for glasses and contact lenses. This study evaluated visual acuity differences between dominant and nondominant eyes through analyzing refractive power changes in both eyes by the ages. Methods: This study was performed to investigate the relationship between refractive error and dominant eye which had the superiority in the function of binocular. 186 subjects without ocular disease were examined on the dominant eye. The dominant eye was examined by the Hole-in-the-card test. For the consistency of the measurements, we tested refractive power in three times by the same person. Results: Using SPSS, the relationship between vision and the dominant eye was analyzed. 135 people of the whole subjects have the dominant eye on right. The Number of the non-dominant eye is 51. We were divided into 3 types, the group under the age of 10 that begins to expose environment factor affect on vision (the average age $8.8{\pm}1.18$) and the age group of 10 to 20 that begins to change refractive power in earnest (the average age $14.1{\pm}2.58$) and the group after the age 20 that began to stabilize vision (the average age $51.8{\pm}17.51$). The visual acuity of dominant eye was higher than non-dominant eye in all age groups. Nevertheless, these results were not statistically significant. Mean astigmatism of dominant eye was smaller than the non-dominant eye, and this is significant, statistically (p=0.017<0.05). Conclusions: It is expected that the balanced eye with a lower level of astigmatism has a more possibility become a dominant eye.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.3
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• pp.327-331
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• 2011

Purpose: The purpose of this study was an accurate grasp of the astigmatic change due to eyes accommodation on near vision and suggested problems occurring accommodative astigmatism using near glasses. Methods: 154 subjects(308eyes) from 20 to 40 years selected for this study who had many opportunity of near vision. First, far vision corrective refraction measured using the phoropter, and then both eyes opened simultaneously for maintaining the function of binocular put away dot chart 40 cm. One eye was fogging and the other eye measured near vision astigmatism axis and degrees astigmatism using cross cylinder, and then compared with far astigmatism. Results: Increased degree of astigmatism persons on near vision more than decreased or did not changed degree of astigmatism persons, which could affect visual acuity more than 0.75 diopters in 30 eyes with an increase of 9.7% of total subjects. Direct astigmatism and oblique astigmatism were increased on near vision. Astigmatic axes were rotated base in direction on both eyes and 66.9% of subjects were more than ${\pm}$5$^{\circ}$ rotation. Due to the rotation axis of astigmatism, residual astigmatism is expected to occur and expect to adversely affect the eyes. Conclusions: Long-term using the glasses without correction of increased astigmatic and rotated axis on near vision should occur new residual astigmatism and increase the asthenopia also. Considered to be taken astigmatic change on near vision during near refraction examination.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.2
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• pp.159-164
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• 2012

Purpose: Of the various methods of vision training, the essay aims to explore the effective ways of using the Fresnel prism lens in order to expand the positive fusional vergence for the patient having specific condition of convergence insufficiency or basic exophoria. Methods: 15 students of city of Daejeon university without an eye disease (average age $22.73{\pm}1.68$) were selected and underwent the subjective refraction test and binocular vision test, and recording their test results before vision training and replacing an identical frame with a lens of same quality after the full calibration, the lens was then adhered with the Fresnel prism lens and continued to train for thirty minutes daily during two weeks. Afterwards, the binocular vision test was reattempted. The observation of the change in the results of the binocular vision test in use of the fresnel prism lens in the vision training test was researched. Results: After training, the positive fusional vergence had increased to a number of $22.27{\pm}2.26$ $\Delta$, to 7.80 $\Delta$, at near, the fused cross cylinder test increased to an average of $0.55{\pm}0.09$ D, 0.40 D after training, showing a normal result. The value of negative relative accommodation after training had an average of $2.22{\pm}0.08$D, showing that 0.42 D had increased. The value of near point of convergence after training had an average of $6.13{\pm}0.53$ cm, showing that 2.80 cm had decreased. To patients who had convergence insufficiency or basic exophoria, the value of the near vision test that used the Fresnel prism lens which was able to expand BO positive fusional vergence had increased without phoria. Conclusions: The changes were tested and the effectiveness of the Fresnel prism lens, due to the nature of the lens itself, helped with both cosmetic effects and cost. It also allows good optical correction effects, in addition to these clinical effects indicated before. Therefore, it may be determined that the Fresnel prism lens binocular vision therapy for patients is more popular and highly recommended.

• 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%.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.2
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• pp.153-158
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• 2012

Purpose: The purpose of this study was to evaluate the convergence accommodation to convergence (CA/C) ratio and to investigate relationships among age, accommodative amplitude and PD (interpupillary distance) of adults in their early twenties with normal binocular vision. Methods: 44 subjects (mean age, $21.75{\pm}1.16$ years) with healthy eyes were examined. The CA/C ratios were measured by using the difference of Gaussian (DOG) target with retinoscopy. Results: The mean CA/C ratio was $0.052{\pm}0.017$ D/$\Delta$. A moderate negative correction was present between CA/C ratio and age (r = -0.50, p = 0.0005), and a highly positive correction was found between CA/C ratio and accommodative amplitude (r = 0.79, p<0.0001). There was no relation between PD and CA/C ratio. Conclusions: The CA/C ratio presented was mean value for adults in their early twenties with healthy eye between 19 and 25 years of age. There was a high correlation between accommodative amplitude and CA/C ratio. Therefore, the CA/C ratio will be useful basic information for comparison in age, gender and binocular anomalies with similar data from other countries.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.3
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• pp.371-376
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• 2014

Purpose: The aim of this study was to explore the effect of artificially decreased eye in normal vision on eye-hand coordination (EHC) when using the Lee-Ryan Eye-Hand Coordination Test recently reported. Methods: Eleven adults with normal vision aged $29.46{\pm}5.94$ years participated for this study where a non-dominant eye artificially induced moderate refractive amblyopic vision at near by adding a plus lens conducted EHC tasks and then did the test again under normal vision following 2 weeks. To investigate the ability of EHC, 7 tasks including individually different level of difficulty in the Lee-Ryan EHC Test were selected to compare and analyze EHC in terms of two independent variables such as time taken and the number of errors. Results: In time taken, subjects with artificially decreased vision took more time than normal vision under monocular conditions (p=0.013), while those with the decreased vision completed their tasks faster than normal vision under binocular conditions (p=0.001). In the number of errors, subjects with the decreased vision made more mistakes (p<0.001) as shown in time taken, whereas there was no difference between monocular and binocular viewing conditions in the decreased vision. Conclusions: Unlike previous EHC tests including limitations for application, deficit in EHC can be screened by the Lee-Ryan EHC Test developed based on simple computer-based system. Therefore, it is considered that further studies relevant to deficits in visual function such as amblyopia will be carried out in clinics as well as research.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.4
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• pp.555-560
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• 2013

Purpose: The aims of this study were to investigate the stereoacuity and subjective symptoms of aniseikonia with prescription of the size lens. Methods: Participants were myopic anisometropia patients with the binocular refraction difference between 1.75 D~3.50 D. Inclusion criteria of participants were no ocular pathology, no amblyopia, more than 1.0 of corrected visual acuity. With fully corrected spectacles and a correction with the size lens, Awaya aniseikonia test and Randot Stereo test were conducted respectively. In addition, subjective symptoms were also examined using questionnaire. Results: As the anisometropia increased, the aniseikonia increased. Under the anisometropia with same refractive correction was different for each individual. The prescription of size lens caused less aniseikonia than the general prescription of glasses. In addition, prescription of the size lens improved stereoacuity and relieved the symptoms of asthenopia. Conclusions: The prescription of size lens that can correct aniseikonia with prescription of glasses can improve stereoacuity and reduced asthenopia.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.3
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• pp.37-42
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• 2009

Purpose: There is uncertainty if the vergence facility would provide clinically significant supplementary information to the fusional vergence measurements. The purpose of this study was to determine the relationship between vergence facility and fusional vergence in a group of symptomatic subjects. Methods: A total of 114 symptomatic subjects aged 9 to 13 years, who passed the vision screening test, participated in this study. Vergence facility was measured with 8$\Delta$ BI/8$\Delta$ BO flipper lenses and a suppression control target, the 20/30 letter line on Vectogram 9 (Bernell, USA). Near fusional vergence was measured with a single 20/30 vertical line target by Von Graefe technique. In order to avoid excessive convergence stimulation, negative fusional vergence (NFV) range (blur, break and recovery) was measured followed by positive fusional vergence (PFV) ranges (blur, break and recovery). Results: Pearson correlations were calculated and showed no correlations between vergence facility and any of fusional vergence measurements (p>0.05). Also, there were no significant differences of vergence facility measurements on the compensating vergence that passed or failed Sheard and Morgan's criterion for comfortable vision (p>0.05). Conclusions: There was no correlation between vergence facility and fusional vergence among symptomatic subjects. Hence, both vergence facility and fusional vergence should be assessed for those with binocular dysfunction in order to make an accurate diagnosis and management plan.