• Journal of Korean Ophthalmic Optics Society
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• v.8 no.2
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• pp.47-52
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• 2003

117 undergraduate ophthalmic optics students volunteered to participate in this study. They ranged in age from 19 to 26 years. Subject, had best corrected visual acuity of at least 1.0 in both eyes, no strabismus, no amblyopia, and no history of ocular surgery. 37 subjects are esphoria and 25 subjects are $3{\Delta}$ and less, and the rest of 12 subjects show more $4{\Delta}$. Average phoria amount is $2.96{\Delta}$ at far distance and $1.08{\Delta}$ at near distance, respectively. The variation of phoria amount in far and near distance, unchanging subjects are 3, 8 subjects are increase esophoria amount, and 26 subjects are phoria amount decreasing or appear exophoria. The reason of esophoria amount is decreasing in near distance, and the results are convergence burden decreases. At positive relative convergence, the expected value in far distance, blurred point is 7, break point is 16, and recovery point is 12. And negative relative convergence, break point is 7 and recovery point is 13, respectively. Moreover, at positive relative convergence, the expected value in near distance is blurred point is 8, break point is 7 and recovery point is 22. And negative relative convergence, blurred point is 2, break point is 8 and recovery point is 12, respectively.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.2
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• pp.149-156
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• 2013

Purpose: The aim of this study was to determine a suitable type and size of Hangul fonts for printed materials in the presbyopic age. Methods: Based on the most common Hangul fonts used today, three types of fonts were used Hamchrombatang, Sinmoonmyungjo and Sinmyungjo at small font sizes in the range 9-11 point (pt). Subjects were 101 volunteers aged 41 through 85 years. Near visual acuity (VA) was corrected to read VA 0.5 at 40 cm after distance correction. The subjects were asked to read words containing 88 characters in 10 pt after a question about preference. Readability was assessed by reading rate that was calculated as the number of words read correctly in one minute (words per minute, wpm). Results: The most preferred font type was Simmyungjo at small font sizes. Although preferred font sizes were different in each font type, Sinmyungjo was generally preferred at 10 pt more than other fonts. Hamchrombatang and Sinmyungjo were read significantly faster than Sinmoonmyungjo. There was a weak negative relationship between readability and age in Sinmyungjo. In comparing between the top 10% and the bottom 10% group sorted by reading rate, the top group showed lower average age and addition than the bottom group, however there were no significant differences in reading rate among the fonts. Conclusions: Although increasing age tends to be low in readability for Sinmyungjo, in the light of preferred font and readability, it is recommended to use a 10 pt Sinmyungjo font in printed materials for the presbyopic age.

• Journal of Korean Ophthalmic Optics Society
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• v.21 no.3
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• pp.243-251
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• 2016

Purpose: This study evaluates the effectiveness of intermittent exotropia vision training through follow up of average 3 years using proprioceptive test (Maindot test). Methods: 35 people (18 men, 17 women) with mean age of 13.48 (${\pm}2.45$) with corrected visual acuity of 0.9 or higher and normal binocular vision and control were observed for changes between before, after, and 3 years following the vision training during the period from 2005 to 2009. Results: After training, the correlation between the changed amount of deviation and PRC(diplopia) value and symptoms was not significant (p>0.05). However, it showed a statistically significant (p<0.001) correlation that change of the binocular proprioceptive sense abilities is decreased subjective symptoms. Conclusions: Binocular proprioceptive sense may be used in variety of purposes and applications such as predictive evaluation of binocular symptoms, binocular function performance evaluation after vision training and prism treatment.

• Journal of Korean Ophthalmic Optics Society
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• v.21 no.3
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• pp.253-257
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• 2016

Purpose: To determine whether the distance between objects and the size of object are factors to be able to affect dynamic stereoacuity. Methods: Subjects were 37 adults (26 males and 11 females) with an average age of $23.89{\pm}1.76$. Refractive error was fully corrected for all subjects and each visual acuity of them was over 0.9. Three rods test was performed for measurement of stereoacuity. The viewing angles from left rod to right rod were set $5^{\circ}$, $10^{\circ}$, and $15^{\circ}$ and the rod thickness used 7 mm, 14 mm, and 21 mm, respectively. Stereoacuity was repeatedly measured three times in each test condition at 2.5 m distance, and reported the average value of them. Results: When rod thickness was 7 mm or 14 mm, dynamic stereoacuity decreased as the viewing angle increased, and they were significantly decreased (p<0.01) at viewing angles of $10^{\circ}$ and $15^{\circ}$ as compared with that of at $5^{\circ}$, respectively. When rod thickness was 21 mm, dynamic stereoacuity decreased as the viewing angle increased, especially, that of at $15^{\circ}$ decreased significantly (p<0.01) as compared with that of at $5^{\circ}$. The dynamic stereoacuity depending on the rod thickness have an increasing tendency as the rod thickness increased. Conclusions: The viewing angle between objects and the size of viewing object were factors that affect to dynamic stereoacuity.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.3
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• pp.65-73
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• 2009

Purpose: This study was conducted to investigate the changes in distance refractive power and reading addition that occur after wearing corrective glasses for prebyopia. Methods: The subjects aged 42 to 75 years who had no ophthalmologic diseases and did not undergo cataract or retina surgery, had a corrected visual acuity of 20/20 and did not have a previous history of wearing corrective glasses for presbyopia. These subjects were divided into 3 groups: the control, reading spectacles and multifocals wearing group and they were measured for distance refractive power and reading addition at their visit. The maximum follow-up period was 73 months. Results: As for distance refractive power, the power tends to shift to hyperopia depending on age (r=0.486, p<.001) and 50.0% of the subjects increased plus power during this study period. Plus power Increments per year in distance refractive power in the reading spectacle wearing group were significantly different with control and multifocals wearing group (p<.05). On the other hand, the multifocals wearing group's increments were not different with control. Increments in reading addition were also increased in the reading spectacles group than in the control and multifocals wearing groups (p<.05). Conclusions: The age related hyperopic shift could be occurred in the elderly people, routine refraction is mandatory. And reading spectacles could induce an age related hyperopic shift and the additional need for reading addition that the prescription of multifocals may reduce changes in distance refractive power and reading addition.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.1
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• pp.115-119
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• 2009

Purpose: This study has been conducted to know the relation among accommodative amplitude, response, and facility. Methods: 61 subjects were students without any ocular diseases and presbyopia in a university, Korea. After far distance visual acuity was fully corrected, the amplitude was measured through Push-Up test, the response was measured through Jackson crossed cylinder ${\pm}$0.25D and the facility was measured through +2.00/ -2.00D flipper. Results: The relation among accommodative facility, response and amplitude had not indicate significant level in monocular and binocular. In binocular, 12 eyes (19.6%) had a difference in amplitude, 9 eyes (14.7%) had a difference in response, 2 eyes (3.2%) had a difference in facility from norm which would be expected from their age. 4 eyes (6.5%) had difference in both amplitude and response. 2 eye (3.2%) had difference in both amplitude and facility. In all three of the amplitude, response, facility had not difference. Conclusions: The evaluation of accommodative functions and a patients accommodative dysfunction is examined all facets of amplitude, response, and facility.

• Journal of The Korean Ophthalmological Society
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• v.59 no.11
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• pp.1087-1090
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• 2018

Purpose: To report a case of trochlear nerve palsy caused by quadrigeminal cistern lipoma located in the dorsal midbrain. Case summary: A 65-year-old male visited our clinic for intermittent vertical diplopia over 2-year period. Symptoms of diplopia had worsened over the past two weeks. He had no previous medical history except having had diabetes for 1 month. The best-corrected visual acuity was 20/25 in the right eye and 20/20 in the left eye. Pupillary examination was not remarkable. Extraocular examination showed 4 prism diopters (PD) left hypertropia at distant gaze and 4 PD exotropia at near gaze, with adduction elevation of the left eye. The Bielschowsky head tilt test revealed 6 PD left hypertropia on the left gaze and orthotropia on the right tilt. Fundus examination showed excyclotorsion of the right eye and incyclotorsion of the left eye. Brain magnetic resonance imaging revealed quadrigeminal cistern lipoma. Prism glasses were prescribed to alleviate diplopia, and we followed up the lesions without further treatment. Conclusions: Trochlear nerve palsy can be caused by quadrigeminal cistern lipoma; however, it is uncommon for this condition to be caused by a compressive lesion. Prompt neuroimaging can be helpful to rule out the causes of this condition in patients with atypical symptoms.

• Journal of The Korean Ophthalmological Society
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• v.60 no.2
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• pp.126-134
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• 2019

Purpose: To assess the accuracy of toric intraocular lens (IOL) implantation by the location and size of the corneal incision. Methods: We retrospectively reviewed the medical records of 98 patients (98 eyes) who underwent phacoemulsification with toric IOL implantation from January 2014 to March 2017. The patients were divided into two groups: group 1 got an incision of the superior side of the cornea (n = 54) and group 2 received an incision on the temporal side of the eye (n = 44). For both groups, incisions were made at their steep corneal astigmatism axises. Each group was further divided into subgroups for whom different sized blades were employed (2.75 vs. 2.2 mm widths). We measured the refractive index and autokeratometric parameters. We postoperatively assessed residual astigmatism and any reduction thereof. Results: In both groups, uncorrected and best-corrected visual acuity, refraction cylinder astigmatism, and autokeratometric astigmatism improved statistically. Between two groups, corneal astigmatism decrease was not significant. Residual astigmatism also showed no significant differences between the two. Patients in both groups treated using 2.75 mm wide blades exhibited greater increases in corneal astigmatism. Conclusions: During cataract surgery, precise correction of astigmatism via toric IOL implantation is possible when surgically induced astigmatism is minimized by careful choice of the location and size of the corneal incision.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.4
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• pp.533-538
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• 2014

Purpose: This study is to investigate correlation between eye fatigue and letter contrast according to letter contrast changes on monitor display. Methods: Reading speed test were carried out for 53 subjects (mean age: $22.68{\pm}1.85$ years) who have over Best-corrected visual acuity (BCVA) 1.0, and 45 subjects, who could read over 123 out of 163 letters among 53 subjects were selected. They were asked to read the letters which were composed of Black (contrast 100%), Dark gray (contrast 80%), Gray (contrast 80%), Light gray (contrast 30%) randomly. The change of their eye fatigue by letter contrast on monitor display was measured by monitoring their eyes with an eye-tracker while they were reading letters. Results: Event Duration (sec) was 33.635 for Black, 32.266 Dark gray, 33.936 for Gray, and 34.848 for Light gray. Average of Fixation Duration (sec) was 0.224 for Black, 0.218 for Dark gray, 0.239 for Gray and 0.243 for Light gray. Average of Pupil diameter (mm) was 41.133 mm for Black, 41.160 mm for Dark gray, 40.880 mm for Gray and 40.459 mm for Light gray. Frequency (blinks/sec) was 0.211 for Black, 0.206 for Dark gray, 0.221 for Gray, and 0.238 for Light gray. Conclusions: Event Duration and average of Fixation Duration were the shortest for Dark gray and the longest for Light gray. In average Pupil diameter was the biggest Dark gray and the smallest for Light gray. Blink Frequency (blinks/sec) was the lowest for Dark gray and the highest for Light gray. Visual fatigue by brightness of letters on monitor display was the least for Dark gray followed by Black, Gray and Light gray.

• 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.