• The Korean Journal of Vision Science
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• v.20 no.4
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• pp.421-429
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• 2018

Purpose : We identified correlation between macular thickness and RNFL (retina nerve fiber layer) measured by OCT and axial length in Korean children divided as three groups according to refractive errors. Methods : In total, 134 eyes of 67 Korean children who experienced no eye disease and ophthalmology surgery were involved in this study and then divided as three groups such as hyperopic, emmetropic and myopic groups. Macular thickness and RNFL thickness were measured with Cirrus HD-OCT, and axial length was done with IOL Master.Macular thickness and RNFL thickness were measured by Cirrus HD-OCT, and axial length using IOL Master. Correlation between axial length and retinal thickness in three groups according to refractive errors was investigated. Results : The type of refractive error measured by axial length was myopic, emmetropic and hyperopic groups in order, showing significant difference (p<0.05). The center thickness of macular was myopic, emmetropic and hyperopic groups in order, showing significant difference(p<0.05). The thicknesses of superior, nasal and inferior regions in peripheral macula were the thinnest in myopic group (p<0.05). It was shown that positive correlation was found between the center thickness of macula and axial length (r=0.283, p<0.05), while negative correlation was found between the peripheral thickness of RNFL and axial length. The temporal thickness of RNFL represented the thickest in myopic group, showing positive correlation with axial length(r=0.39, p<0.05). The superior, nasal and inferior thickness of RNFL represented negative correlation with axial length, showing statistically significant in the nasal thickness of RNFL(r=-0.23, p<0.05). Conclusion : Through this study, we identified correlation between macular thickness, the thickness of RNFL and axial length using OCT in Korean children, and also found the differences in three refractive error groups.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.10-15
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• 2020

Ultraviolet rays, which have wavelengths smaller than 400 nm, are very harmful to the eyes. Recently, high-energy visible light was also revealed to be harmful to retinal cells. Therefore, polymer eyeglass lenses that can block UV and high-energy visible light are needed for eye health. In this study, high-refractive-index polymer eyeglass lens, n=1.67, were manufactured using the injection-mold method with the m-xylene diisocyanate monomer, 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol monomer, benzotriazole UV absorber, release of alkyl phosphoric ester, dye mixture of CI solvent violet 13, and catalyst of dibutyltin dichloride mixture. A multi-layer anti-reflection coating was applied to manufactured polymer eyeglass lenses for both sides using an E-beam evaporation system. The optical properties of the manufactured lenses with the UV and high-energy visible light-blocking function were analyzed by UV-visible spectrophotometry. As a result, the polymer eyeglass lens with a UV absorber of 0.5 wt. % blocked 99% of UV and high-energy visible light shorter than 411 nm. The average transmittance of the polymer eyeglass lens with a UV absorber of 0.5wt.% was 97.9% in the range of 460 ~ 660 nm for photopic eye sensitivity higher than 10%. Therefore, clear image acquisition in photopic vision is possible.

• Science of Emotion and Sensibility
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• v.25 no.1
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• pp.79-90
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• 2022

IThe perception of sub-second duration through the visual sensory system is affected by non-temporal characteristics (factors other than the duration of the stimulus). However, studies have shown that if distance information is abundant and size constancy maintained, the duration of the target is constantly perceived. The current study examined the relationship between size and time perception constancy in a three-dimensional environment with limited distance information. A device was constructed to limit the participants' bilateral and monocular cues. This prevented participants from maintaining size constancy, resulting in size illusions that could not accurately perceive physical size. In Experiment 1, the size of the physical stimulus of reference and test stimuli were the same at all viewing distances. The results suggest that, despite the same physical size, stimuli with close observations were perceived to be greater and lasted longer. In Experiment 2, the retinal size of the reference stimuli and test stimuli was controlled equally at all viewing distances. As a result, although the physical size of the stimuli increased as the observation increased, the perceived size of all the stimuli was the same. Therefore, the duration of the target was constantly perceived at all viewing distances. The results of this study demonstrate that even when distance information is limited, time perception is affected by the perceived size of the object. It also suggests that when rich distance information exists, the duration of the object can be constantly perceived even if the observation distance varies.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.4
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• pp.381-392
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• 2022

Objectives: Objective of this study is to review briefly exposure characteristics, monitoring instruments and threshold limit values for extremely low frequency-magnetic field (ELF-MF) methods. This study was undertaken through brief literature review. We performed a literature search in PubMed to identify ELF-MF studies conducted in workplaces. Initial search keywords such as 'extremely low frequency-magnetic field (ELF-MF)' and 'electromagnetic fields (EMF)' combined or singly. We limited our review to occupational rather than general nonworkplace environmental exposures. Methods: The contents we reviewed: key industry and occupations generating ELF-MF, several direct-reading instruments monitoring ELF-MF and threshold limit values (TLV) preventing health effects may be caused by the exposure to ELF-MF. Results: The industries related to the generation and supply of electricity, electrolytic installations, welding, and induction heating and more were regarded as high ELF-MF exposure industries. All jobs handling or employed performed in power cable lines, electrical wiring, and electrical equipment are found to be exposed to ELF-MF. Threshold or ceiling limit, 1,000 µT, is established to prevent acute effects of exposure to low-frequency EMFs on the nervous system: the direct stimulation of nerve and muscle tissues and the induction of retinal phosphenes. The International Agency for Research on Cancer (IARC) has classified ELF-MF as possibly carcinogenic to humans chiefly based on epidemiological studies on childhood leukemia. However, a causal relationship between magnetic fields and several types of cancer including childhood leukemia has not been established nor has any other long-term effects. Risk management using precautionary measures, has been initiated by the US and EU to prevent chronic health effects related to ELF-MF exposure in workplaces. Conclusion: This study recommends the implementation of various measures such as theestablishment of occupational exposure limit values for ELF-MF and precautionary principle to prevent potential chronic occupational health effects may be caused by ELF-MF in Korea.

• Journal of the Korea Society of Computer and Information
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• v.27 no.12
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• pp.29-40
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• 2022

In this paper, we studied a system that detects and analyzes the pathological features of diabetic retinopathy using Mask R-CNN and a Random Forest classifier. Those are one of the deep learning techniques and automatically diagnoses diabetic retinopathy. Diabetic retinopathy can be diagnosed through fundus images taken with special equipment. Brightness, color tone, and contrast may vary depending on the device. Research and development of an automatic diagnosis system using artificial intelligence to help ophthalmologists make medical judgments possible. This system detects pathological features such as microvascular perfusion and retinal hemorrhage using the Mask R-CNN technique. It also diagnoses normal and abnormal conditions of the eye by using a Random Forest classifier after pre-processing. In order to improve the detection performance of the Mask R-CNN algorithm, image augmentation was performed and learning procedure was conducted. Dice similarity coefficients and mean accuracy were used as evaluation indicators to measure detection accuracy. The Faster R-CNN method was used as a control group, and the detection performance of the Mask R-CNN method through this study showed an average of 90% accuracy through Dice coefficients. In the case of mean accuracy it showed 91% accuracy. When diabetic retinopathy was diagnosed by learning a Random Forest classifier based on the detected pathological symptoms, the accuracy was 99%.

• BMB Reports
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• v.56 no.6
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• pp.359-364
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• 2023

KAI1/CD82, a membrane tetraspanin protein, can prevent various cancers and retinal disorders through its anti-angiogenic and anti-metastatic capacity. However, little is known about its anti-inflammatory effect and molecular mechanism. Therefore, the present study aimed to inLPSvestigate effect of a recombinant protein of the large extracellular domain of human KAI1 (Gly 111-Leu 228, rhKAI1) on lipopolysaccharides (LPS)-stimulated RAW264.7 macrophage-like cells and mouse bone marrow-derived macrophages (BMDM) and to identify its underlying mechanism. Our data showed that rhKAI1 suppressed expression levels of classically macrophages (M1) phenotype-related surface markers F4/80+CD86+ in LPS-stimulated BMDM and RAW264.7 cells. In addition, LPS markedly increased mRNA expression and release levels of pro-inflammatory cytokines and mediators such as interleukin (IL)-1β, IL-6, tumor necrosis factor-α, cyclooxygenase-2, nitric oxide and prostaglandin E2, whereas these increases were substantially down-regulated by rhKAI1. Furthermore, LPS strongly increased expression of NF-κB p65 in the nuclei and phosphorylation of ERK, JNK, and p38 MAPK. However, nuclear translocation of NF-κB p65 and phosphorylation of JNK were greatly reversed in the presence of rhKAI1. Especially, rhKAI1 markedly suppressed expression of toll-like receptor (TLR4) and prevented binding of LPS with TLR4 through molecular docking predict analysis. Importantly, Glu 214 of rhKAI1 residue strongly interacted with Lys 360 of TLR4 residue, with a binding distance of 2.9 Å. Taken together, these findings suggest that rhKAI1 has an anti-inflammatory effect on LPS-polarized macrophages by interacting with TLR4 and down-regulating the JNK/NF-κB signaling pathway.

• Exercise Science
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• v.21 no.3
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• pp.289-298
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• 2012

In the present study, we investigated the effect of treadmill exercise on apoptotic neuronal cell death in the retinas of streptozotocin-induced diabetic rats. Twenty-eight male Sprague-Dawley rats were used for this study. The animals were divided into four groups(n = 7 in each group):(1) control group, (2) exercise group, (3) diabetes-induced group, (4) diabetes-induced and exercise group. Diabetes mellitus(DM) was induced by intraperitoneal injection of streptozotocin. The rats in the exercise groups were forced to run on the treadmill for 30 minutes once a day, five times per a week, during 12 weeks. In this study, a terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling(TUNEL) assay and western blot for the expressions of caspase-3, cytochrome c, Bax, and Bcl-2 in the retinas were conducted for the detection of apoptotic retinal cell death. The present results showed that the number of TUNEL-positive cells was increased in the retinas of the diabetic rats, whereas treadmill exercise suppressed this number. The expressions of pro-apoptotic factors caspase-3, cytochrome c, and Bax were enhanced and the expressions of anti-apoptotic factor Bcl-2 was decreased in the retinas of the diabetic rats. In contrast, treadmill exercise suppressed the expressions of caspase-3, cytochrome c, and Bax and increased the expression of Bcl-2. The present study demonstrated that treadmill exercise suppressed diabetes-induced apoptotic neuronal cell death in the retinas. Based on the present results, treadmill exercise may be effective therapeutic strategy for the alleviating complications of diabetes patients.

• The Korean Journal of Nuclear Medicine
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• v.33 no.5
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• pp.439-451
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• 1999

Purpose : It is important to differentiate malignant from benign lesions of intraocular masses in choosing therapeutic plan. Biopsy of intraocular tumor is not recommended due to the risk of visual damage. We evaluated the usefulness of F-18-FDG PET imaging in diagnosing intraocular neoplasms. Materials and Methods: F-18-FDG PET scan was performed in 13 patients (15 lesions) suspected to have malignant intraocular tumors. There were 3 benign lesions (retinal detachment, choroidal effusion and hemorrhage) and 10 patients with 12 malignant lesions (3 melanomas, 7 retinoblastomas and 2 metastatic cancers). Regional eye images ($256{\times}256$ and $128{\times}128$ matrices) were obtained with or without attenuation correction. Whole body scan was also performed in eight patients (3 benign and 6 malignant lesions). Results: All malignant lesions were visualized while all benign lesions were not visualized. The mean peak standardized uptake value (SUV) of malignant lesions was $2.64{\pm}0.57g/ml$. There was no correlations between peak SUV and tumor volume. Two large malignant lesions ($> 1000 mm^3$) showed hot uptake on whole body scan. But two medium-sized lesions ($100-1000mm^3$) looked faint and two small ($<100mm^3$) lesions were not visualized. The images reconstructed with $256{\times}256$ matrix showed lesions more clearly than those with $128{\times}128$ matrix Conclusion: F-18-FDG PET scan is highly sensitivity in detecting malignant intraocular tumor For the evaluation of small-sized intraocular lesions, whole body scan is not appropriate because of low sensitivity. A regional scan with sufficient acquisition time is recommended for that purpose. Image reconstruction in matrix size of $256{\times}256$ produced clearer images than the ones in $128{\times}128$, but it does not affect the diagnostic sensitivity.

• Clinical and Experimental Pediatrics
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• v.52 no.6
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• pp.674-679
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• 2009

Purpose : The authors aimed to analyze the long-term effects of treatments, especially external beam radiotherapy (EBRT), in bilateral retinoblastoma patients. Methods : This retrospective study analyzed the medical records of 22 bilateral retinoblastoma patients who were registered between October, 1987 and October, 1998 and followed-up for more than 10 years. They were treated by enucleation, EBRT, and systemic chemotherapy. Age at diagnosis, sex, delay prior to treatment, Reese-Ellsworth (RE) classification, and the local treatment modalities were analyzed in relation to recurrence-free survival (RFS) and complications. Results : Median age at diagnosis was 7.0 months (range 1.7-31.6 months). Leukocoria was the most common presenting feature. Two patients had a familial history. The RE classifications of the 44 eyes were group II in 4, III in 14, IV in 4, and V in 22. At the end of a median follow-up period of 141 months (range 55-218 months), 20 patients were alive. The 10-year ocular survival rate of the 44 eyes was $56.8{\pm}7.5%$. The 10-year RFS and ocular survival rate of the 29 eyes treated by combined EBRT and chemotherapy were 75.9% and 86.2%, respectively. Treatment delay (>3 months) was found to be related to higher risk of recurrence. Complications after EBRT were cataract, retinal detachment, phthisis bulbi, and facial asymmetry. No patient developed a second malignancy during the follow-up period. Conclusion : Early detection and prompt treatment can increase ocular survival rates. In addition, careful attention should be paid to possible long-term sequelae in these patients.

• Clinical and Experimental Pediatrics
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• v.50 no.5
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• pp.436-442
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• 2007

Purpose : To promote awareness and efforts by pediatricians to identity and prevent child abuse by investigation of characteristics of victim and types of injury caused by abuse. Methods : A retrospective study was performed with 20 patients who had been diagnosed or suspected as child abuse at Hallym University Hospital from January 1999 to December 2005. The medical records, radiologic documents, and social worker's notes were reviewed to investigate age, sex, visiting time, form of abuse, perpetrator, risk factor, and type of injury. Results : The mean age of the subjects was 2.8 years. Fourteen patients were between 0-1 years old, 2 patients between 1-6 years old, 3 patients between 7-12 years old, and 1 case over 13 years old. The ratio of male to female was 1:1. The majority of these patients (70%) visited via emergency department. Eight five percent of these patients reported with physical abuse, 5% psychological abuse, 5% sexual abuse, and 5% neglect respectively. The suspected perpetrator was the biological father in six cases, the biological mother in three cases, the stepmother in two cases, caregiver in one case, relatives in one case and "unknown" in six cases. Bruise and hematoma (80%) were the most common physical findings. Skull fractures were diagnosed in six cases, long bone fractures in two cases, hemoperitoneum in two cases, subdural hemorrhage in 10 cases, epidural hemorrhages in two cases, subarachnoidal hemorrhages in two cases, and retinal hemorrhages in five cases respectively. Seventeen cases required hospitalization and surgical operations performed were in nine cases. Four patients died and three patients had sequalae such as developmental delay and quadriplegia. Conclusion : Child abuse results in high mortality and morbidity in victims. Therefore early recognition and prevention is very important. Pediatricians should always suspect the possibilities of abuse in cases of fracture, intracranial hemorrhage, abdominal injury, or even any injury to the body. We recommend that the clinical investigation of suspicious children should include a full multidisciplinary social assessment, a skeletal survey and CT or MRI.