• Journal of Korean Ophthalmic Optics Society
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• v.17 no.1
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• pp.59-65
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• 2012

Purpose: The purpose of this study was to determine the distribution and correlation of accommodative lag with refractive error. Method: We had tested the clinical refraction and the accommodative lag in clinically normal 49 young adults (total 98 eyes) aged 18 to 25 years without abnormal binocular function. Monocular and binocular accommodative lag were tested with 0.50 D cross-cylinder lens and near vision test chart which had cross-hairs after full correction of LogMAR visual acuity over 0.05. Results: There was no statistical differences in monocular accommodative lag between right ($0.64{\pm}0.64$ D) and left eye ($0.63{\pm}0.64$)(p=0.858). The accommodative lag of male was higher than female and the range of the value was broader than female in binocular accommodative lag (p=0.015). The wider the inter-pupillary distance was, the higher the accommodative lag was (p=0.003). However, there were no differences with age (p=0.800) and dominant eye (p=0.402). The ranges of accommodative lag of low, middle, and high myopia were 0.75 ~ -0.25 D, 1.25 ~ -0.50 D, and 1.50 ~ -0.75 D, respectively, and the regression was 'y = -0.03953x+0.09205'. Conclusions: These data suggest that clinically normal young adults with high amounts of refractive error have more variable accommodative lag and increased spherical equivalent refraction.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.3
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• pp.383-387
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• 2014

Purpose: To investigate the effect of corneal unique shape to changes of refractive full corrections when pupil size changes. Methods: Subjective refraction for monocular full correction was performed to 30 subjects ($23.33{\pm}1.78$ of age, 60 eyes) in two room conditions, 760 lx and 2 lx, respectively. Pupillary diameter was measured in two conditions and the change pattern was analyzed using a peak data of corneal topography. Results: Pupillary diameter was 3.74~4.00 mm in 760 lx and 5.52~5.90 mm in 2 lx. By comparison with refractive data in 760 lx, those data in 2 lx was changed as follows: more (-) spherical power of 17 eyes (28.3%), more (+) spherical power of 10 eyes (17.7%), more (-) cylinderical power of 17 eyes (28.8%), less (-) cylinderical power of 9 eyes (15.3%), and astigmatic axis rotation of 36 eyes (62.1%). From peak data of corneal topography, the changing pattern of two principal meridians was classified into 4 types. Conclusions: Expansion of the corneal refractive surface accompanied with pupillary dilation may be a main factor that effects the changing a values of subjective refraction because of unique corneal shape. Therefore, subjective refraction should be performed under the nearest lighting condition to a main living environment.

• 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 KIISE:Software and Applications
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• v.35 no.12
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• pp.780-788
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• 2008

Modeling hand poses and tracking its movement are one of the challenging problems in computer vision. There are two typical approaches for the reconstruction of hand poses in 3D, depending on the number of cameras from which images are captured. One is to capture images from multiple cameras or a stereo camera. The other is to capture images from a single camera. The former approach is relatively limited, because of the environmental constraints for setting up multiple cameras. In this paper we propose a method of reconstructing 3D hand poses from a 2D input image sequence captured from a single camera by means of Belief Propagation in a graphical model and recognizing a finger clicking motion using a hidden Markov model. We define a graphical model with hidden nodes representing joints of a hand, and observable nodes with the features extracted from a 2D input image sequence. To track hand poses in 3D, we use a Belief Propagation algorithm, which provides a robust and unified framework for inference in a graphical model. From the estimated 3D hand pose we extract the information for each finger's motion, which is then fed into a hidden Markov model. To recognize natural finger actions, we consider the movements of all the fingers to recognize a single finger's action. We applied the proposed method to a virtual keypad system and the result showed a high recognition rate of 94.66% with 300 test data.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.2
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• pp.61-71
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• 2009

In this paper, we propose a low-cost and compact motion capture system which enables to play motion games in PS2(Play Station 2). Recently, motion capture systems which are being used as a part in film producing and making games are too expensive and enormous systems. Now days, motion games using common USB camera are slow and have two-dimension recognition. But PSD sensor has a few good points, such as fast and low-cost. In recently year, 3D motion capture systems using 2D PSD (Position Sensitive Detector) optic sensor for motion capturing have been developed. One is Multi-PSD motion capture system applying stereo vision and another is Single-PSD motion capture system applying optical theory ship. But there are some problems to apply them to motion games. The Multi-PSD is high-cost and complicated because of using two more PSD Camera. It is so difficult to make markers having omni-direction equal intensity in Single-PSD. In this research, we propose a new theory that solves aforementioned problems. It can measure 3D coordination if separated two marker's intensity is equal to. We made a system based on this theory and experimented for performance capability. As a result, we were able to develop a motion capture system which is a single, low-cost, fast, compact, wide-angle and an adaptable motion games. The developed system is expected to be useful in animation, movies and games.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.3
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• pp.279-284
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• 2012

Purpose: We measured the amplitude of accommodation using the push-up and push-away tests and near point of convergence (NPC) and investigated the accommodative insufficiency (AI) and convergence insufficiency (CI) in elementary school children of 12~13 years old. Methods: 88 students who aged 12~13 $12.63{\pm}0.51$ years old with more than 1.0 spectacle best corrected visual acuity were examined using push-up and push-away tests. The break and recovery points of NPC also were measured. Results: Mean amplitudes of accommodations using push-up and push-away tests were $11.52{\pm}2.50D$ and $10.06{\pm}1.97D$, respectively in right eye (P<0.001). Mean break and recovery points in NPC were $8.66{\pm}1.99cm$ and $10.98{\pm}2.06cm$. AI and CI showed 28.75% and 30.00% each. 48.75% was within normal range in both amplitudes of accommodations according to their age expected and convergence. Students having both AI and CI were 7.50%. Conclusions: A high correlation between the push-up test and push-away test was found in elementary school children (r=0.6025; P<0.05). Students having normal amplitude of accommodation by their age expected and normal convergence were 71.25% and 70.00%, respectively.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.1
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• pp.93-98
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• 2014

Purpose: We were aim to investigate individual difference of visual acuity (VA) decrease and the change of contrast threshold (CT) according to the level of optically induced retinal defocus. Methods: A total of 69 eyes were examined using consist of ten-graded decimal vision chart (Landolt's ring). After conducted full correction of subject's refractive error, a monocular VA and CT were measured according to sequential increase by 0.25 D each time. Results: VA gradually decreased according to the increase of retinal defocus level. Individual difference of VA decrease was range from 1.2 to 0.6 in retinal defocus induced by +0.25 D. When retinal defocus was induced as much as +0.50 D and +0.75 D, it was in the range of 1.0 to 0.3 and 0.9 to 0.1 respectively. With +1.00 D, some participants didn't even recognize the 0.1 in the chart. With +1.75 D, whole participant did not recognize the 0.1. Also, CT was gradually decreased with increase of the retinal defocus level. Conclusions: Examiners should consider individual difference in the decrease of VA according to the level of residual refractive error when determining final prescription of a patient.

• 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.

• 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 Korean Ophthalmic Optics Society
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• v.14 no.1
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• pp.109-114
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• 2009

Purpose: This study was designed to investigate the condition of refractive correction on wearing glasses currently of elementary school children and their accommodative ability in Jinju city. Methods: Objective refraction, subjective refraction, amplitude of accommodation, negative and positive accommodation, accommodative facility, and dynamic retinoscopy were examined on 60 elemenary school children who aged 8~12 wearing myopiacorrected glasses. Results: The condition of refractive corrections was distributed that a case of full correction was 11.7%, a case of low correction with more than 0.8 visual acuity (VA) was 10%, and a case of low correction with less than 0.8 VA was 78.3% in wearing glasses currently. In results from examination of accommodative ability, the number of children having accommodative anomaly is 8 persons (13.3%), they were divided into accommodation insufficiency (4 persons), accommodative facility insufficiency (2 persons), accommodation excess (1 person), and accommodation insufficiency related to ocular function (1 person). Conclusions: It is demanded a periodic inspection of refractive correction to growing children, and the refractive correction after due consideration to accommodative ability is really needed.