Effect of Intraoperative Mitomycin C on the Surgical Outcomes of Ahmed Glaucoma Valve Implantation with Ciliary Sulcus Tube Placement

Na Eun Kim(Na Eun Kim),Sung Sik Kim(Sung Sik Kim),Jihei Sara Lee(Jihei Sara Lee ),Kwanghyun Lee(Kwanghyun Lee),Hyoung Won Bae(Hyoung Won Bae),Sang Yeop Lee(Sang Yeop Lee),Wungrak Choi(Wungrak Choi),Ch 대한안과학회 2023 Korean Journal of Ophthalmology Vol.37 No.3

Purpose: To evaluate the effect of intraoperative mitomycin C (MMC) on the surgical outcomes of ciliary sulcus (CS) Ahmed glaucoma valve (AGV) tube placement. Methods: A retrospective review of medical records of 54 consecutive patients who underwent AGV implantation with tube placed in CS was performed. Consecutive cases operated without the use of intraoperative MMC from 2017 to 2019 were compared with consecutive cases operated with MMC from 2019 to 2021. Surgical failure was defined as intraocular pressure (IOP) exceeding 21 mmHg in two consecutive visits after postoperative 3 months or ≤30% IOP reduction, IOP ≤5 mmHg in two consecutive visits, or loss of light perception. Kaplan-Meier survival analysis and log-rank test were performed to compare the surgical failure rates. Results: A total of 54 eyes of 54 patients were investigated. Mean follow-up period after AGV implantation was 1.4 ± 0.8 years. The MMC group showed significantly lower IOP during the 1st postoperative month (20.5 ± 8.6 mmHg vs. 15.8 ± 6.4 mmHg, p = 0.027), but the difference did not persist 6 months after the surgery (p = 0.805). The mean number of postoperative antiglaucoma medications was significantly lower in the MMC group in the 1st postoperative month (p = 0.047) but no difference was found at 6 months. No statistical difference was noted in the rates of postoperative complications. Kaplan- Meier survival analysis showed comparable survival rates between MMC group and no MMC group (p = 0.356). Conclusions: The intraoperative use of MMC significantly lowered IOP in the 1st postoperative month but did not increase 6 months success rates in patients receiving AGV tube placement in CS.

Optimization of Delay-Constrained Video Transmission for Ad Hoc Surveillance

Kwanghyun Lee,Sungjin Lee,Sanghoon Lee IEEE 2014 IEEE Transactions on Vehicular Technology VT Vol.63 No.4

<P>Recent increases in demand by militaries and disaster relief operations has greatly accelerated research on delay-constrained video surveillance with low-delay and high-quality video transmission. The following factors should be systematically analyzed due to the tradeoff between low delay and high quality: the visual importance of surveillance objects, quality degradation due to wireless channel dynamics, and variant end-to-end delay. We propose and optimize a low-delay video transmission technique for video surveillance over an ad hoc network. The proposed protocol is composed of intercommunication and intraprocessing parts. Through intercommunication optimization, we identify an optimal routing path and an associated relaying in terms of channel throughput that meet the source-rate, the flow-rate, and delay constraints. Through intraprocessing optimization, we identify an optimal packet length and an associated number of packets to adapt to the delay in the variant dynamic channel. Through simulations, we demonstrate that delay and throughput control significantly contribute to improvements in visual quality of up to 1.7-3 dB compared with conventional schemes.</P>

Single-Crystalline Silicon-Based Heterojunction Photodiode Arrays on Flexible Plastic Substrates

Sangwook Lee,Juree Hong,Ja Hoon Koo,Seulah Lee,Kwanghyun Lee,Seongil Im,Taeyoon Lee IEEE 2011 IEEE transactions on electron devices Vol.58 No.10

<P>A silicon-based photodiode array was fabricated on a flexible polyethylene terephthalate substrate using a transfer printing technique. A heterojunction structure composed of a 15-nm-thick highly doped hydrogenated amorphous-silicon (n<SUP>+</SUP> a-Si:H) layer and a 3-μm-thick p-type single-crystal silicon (p c-Si) membrane layer was adopted as the active layer of the flexible photodiode. The highly ordered photodiode array formed on the flexible substrate exhibited superior stability in electrical properties under bent conditions with no mechanical deformation. The variation of the spectral quantum efficiency (QE) under short-wavelength light illumination (λ ≤ 580 nm) was in excellent agreement with that of a heterojunction photodiode composed of a-Si:H and a bulk c-Si substrate. Relatively low QE values were observed under longer wavelength (λ ≥ 600 nm) illumination due to the finite thickness of the active layer. The <I>C</I>-<I>V</I> measurement results of the fabricated photodiode array were in accordance with the abrupt junction model. A closer inspection of the junction area of the device using high-resolution cross-sectional transmission micrograph exhibited an interface depth of 2 ± 0.5 nm, which is unavoidable in plasma-enhanced a-Si:H deposition processes.</P>

A New Framework for Measuring 2D and 3D Visual Information in Terms of Entropy

Lee, Kwanghyun,Lee, Sanghoon Institute of Electrical and Electronics Engineers 2016 IEEE transactions on circuits and systems for vide Vol.26 No.11

<P>In recent years, the problem of how to more perceptually quantify visualizations of an object and a surface displayed in 3D space between the human eye and a display has been more prominent with rapid increase in the demand for 3D/ultrahigh-definition content. In order to quantify the content information in terms of human visual perception, it is necessary to measure the visual information of 2D and 3D videos accurately in accordance with the human visual system. In this paper, we investigate a new framework for expressing visual information in bits termed visual entropy, based on information theory. 2D visual entropy (2DVE) is composed of two major components: 1) texture entropy on the 2D surface and 2) depth entropy based on the monocular cue. In contrast, 3D visual entropy (3DVE) includes the depth entropy based on the binocular cue in addition to the 2DVE. A series of simulations is conducted to demonstrate the effectiveness of visual entropy, including the degree of accuracy needed to represent perceptual information by means of the texture and monocular and binocular depth entropies. In the simulation results, two successful example applications are also provided, whereby visual entropy is applied to the problems of predicting the visual discomfort experienced when viewing 3D displays and of analyzing performance tradeoffs between 2D and 3D contents.</P>

Quantitative analysis of subjective color appearance based on color and filter transmittance rates

KwangHyun Choi,JiYoung Park,Ho Lee,JinSook Lee 한국색채학회 2017 AIC 2017 Jeju Vol.2017 No.10

Recently, the number of cases in which colored films are put on vehicles or residential windows is increasing to prevent hot summer heat and UV lights inducing skin cancer and aging. However, colored films with a high blocking rate may cause the color constancy, a phenomenon of subjective color appearance. When the film is applied in the wrong way, or part of it is damaged and missing, an optical illusion can occur between the surfaces with and without the film, which leads to confusion and even to an accident. In order to prevent such confusion and potential accidents, we performed color perception experiments according to the color and transmittance, based on which the degree of errors of color perception were derived. Thus, in this study, we identified the tendency of color constancy based on color and filter transmittance rates, and we quantitatively analyzed the degree of errors in color perception by measuring hue, brightness, color purity, and color difference in the Munsell color system. Our experiments were carried out in a space without windows in order to exclude the potential effects of daylight and surrounding artificial light. The inside of the experimental space was finished with N9.5 white (S0500-N) paint. A D65 standard light source was installed on the ceiling. In the experiment, we presented the object in which five different colors such as R, Y, G, B, and P with transmittance rates of 25%, 50%, and 75% were thrown onto the same picture. Subjects were asked to find a color in which a particular shape of N5 was perceived in the Munsell color system and then to write the hue, brightness, and color purity on the evaluation sheet. In addition, we derived a color difference between N5 (original color) and the color that was perceived due to the optical illusion. Thus, we identified the filter color causing the optical illusion the most frequently and the filter transmittance rate.

Object-Based Auto Exposure and Focus Algorithms Based on the Human Visual System

LEE, Kwanghyun,PARK, Suyoung,LEE, Sanghoon The Institute of Electronics, Information and Comm 2009 IEICE transactions on fundamentals of electronics, Vol.92 No.3

<P>For the acquisition of visual information, the nonuniform sampling process by photoreceptors on the retina occurs at the earliest stage of visual processing. From objects of interest, the human eye receives high visual resolution through nonuniform distribution of photoreceptors. Therefore, this paper proposes auto exposure and focus algorithms for the real-time video camera system based on the visual characteristic of the human eye. For given moving objects, the visual weight is modeled for quantifying the visual importance and the associated auto exposure and focus parameters are derived by applying the weight to the traditional numerical expression, i.e., the DoM (Difference of Median) and Tenengrad methods for auto focus.</P>

Biochemical characterization of deblocking aminopeptidase from hyperthermophilic archaeon <i>Thermococcus onnurineus</i> NA1

Lee, Hyun Sook,Cho, Yona,Kim, Yun Jae,Nam, Kwanghyun,Lee, Jung-Hyun,Kang, Sung Gyun Elsevier 2007 Journal of bioscience and bioengineering Vol.104 No.3

<P>A genomic analysis of the hyperthermophilic archaeon <I>Thermoccoccus onnurineus</I> NA1 (TNA1) revealed the presence of a deblocking aminopeptidase (DAP) gene with high similarity to the genes of DAPs from <I>Pyrococcus furiosus</I> (86%) and <I>Pyrococcus horikoshii</I> (83% identity). The optimum aminopeptidase activity of the recombinant enzyme was observed at pH 7.5 and in the range of 90°C to 100°C. The specific aminopeptidase and deblocking activities of the enzyme toward Leu-<I>p</I>NA and Ac-Leu-<I>p</I>NA were 18- and 3-fold higher than those of a <I>P. horikoshii</I> DAP (DAP2), respectively. The enzyme activity was significantly increased by Co<SUP>2+</SUP> ions. The presence of Co<SUP>2+</SUP> ions induced the activation of the enzyme with heating and changed the large oligomer to a dimer. The enzyme activated by Co<SUP>2+</SUP> ions appeared to eventually be inactivated by autodegradation, which was confirmed by mass spectrometry.</P>

Molecular mechanism of Jmjd3‐mediated interleukin‐6 gene regulation in endothelial cells underlying spinal cord injury

Lee, Kwanghyun,Na, Wonho,Lee, Jee Youn,Na, Jungtae,Cho, Heejung,Wu, Hongjin,Yune, Tae Young,Kim, Won‐,Sun,Ju, Bong‐,Gun Blackwell Publishing Ltd 2012 Journal of Neurochemistry Vol.122 No.2

<P><I>J. Neurochem.</I> (2012) <B>122</B>, 272–282.</P><P><B>Abstract</B></P><P>The inflammatory response contributes substantially to secondary injury cascades after spinal cord injury, with both neurotoxic and protective effects. However, epigenetic regulations of inflammatory genes following spinal cord injury have yet to be characterized thoroughly. In this study, we found that histone H3K27me3 demethylase Jmjd3 expression is acutely up‐regulated in blood vessels of the injured spinal cord. We also observed up‐regulation of <I>Jmjd3</I> gene expression in bEnd.3 endothelial cells that were subjected to oxygen‐glucose deprivation/reperfusion injury. When <I>Jmjd3</I> was depleted by siRNA, oxygen‐glucose deprivation/reperfusion injury‐induced up‐regulation of IL‐6 was significantly inhibited. In addition, Jmjd3 associated with NF‐κB (p65/p50) and CCAAT‐enhancer‐binding protein β at the <I>IL‐6</I> gene promoter. The recruitment of Jmjd3 coincided with decreased levels of tri‐methylated H3K27 as well as increased levels of mono‐methylated H3K27 at the <I>IL‐6</I> gene promoter. Furthermore, <I>Jmjd3</I> depletion did not result in significant changes of methylation level of H3K27 at the <I>IL‐6</I> gene promoter. Collectively, our findings imply that Jmjd3‐mediated H3K27me3 demethylation is crucial for <I>IL‐6</I> gene activation in endothelial cells, and this molecular event may regulate acute inflammatory response and integrity of the blood‐spinal cord barrier following spinal cord injury.</P>

3D Visual Activity Assessment Based on Natural Scene Statistics

Kwanghyun Lee,Moorthy, Anush Krishna,Sanghoon Lee,Bovik, Alan Conrad IEEE 2014 IEEE TRANSACTIONS ON IMAGE PROCESSING - Vol.23 No.1

<P>One of the most challenging ongoing issues in the field of 3D visual research is how to perceptually quantify object and surface visualizations that are displayed within a virtual 3D space between a human eye and 3D display. To seek an effective method of quantification, it is necessary to measure various elements related to the perception of 3D objects at different depths. We propose a new framework for quantifying 3D visual information that we call 3D visual activity (3DVA), which utilizes natural scene statistics measured over 3D visual coordinates. We account for important aspects of 3D perception by carrying out a 3D coordinate transform reflecting the nonuniform sampling resolution of the eye and the process of stereoscopic fusion. The 3DVA utilizes the empirical distortions of wavelet coefficients to a parametric generalized Gaussian probability distribution model and a set of 3D perceptual weights. We conducted a series of simulations that demonstrate the effectiveness of the 3DVA for quantifying the statistical dynamics of visual 3D space with respect to disparity, motion, texture, and color. A successful example application is also provided, whereby 3DVA is applied to the problem of predicting visual fatigue experienced when viewing 3D displays.</P>

Effect of red ginseng on visual function and vision-related quality of life in patients with glaucoma

Kwanghyun Lee,Heon Yang,Joo Yeon Kim,Wungrak Choi,Gong Je Seong,Chan Yun Kim,Jun Mo Lee,Hyoung Won Bae 고려인삼학회 2021 Journal of Ginseng Research Vol.45 No.6

Background: Red ginseng has been found to improve ocular perfusion and dry eye syndrome in glaucomatouseyes; however, its effects on visual function and vision-related quality of life have not beeninvestigated. This study sought to evaluate the effects of red ginseng on visual function and visionrelatedquality of life in glaucoma patients using contrast sensitivity and a questionnaire. Methods: Participants were randomly assigned to two groups in this prospective, randomized, doubleblindstudy: in one group, red ginseng was taken first, followed by a placebo, and in the other, placebowas taken first, followed by red ginseng. We measured and compared changes in contrast sensitivityand vision-related quality of life between the two groups. Contrast sensitivity was measured usingOPTEC® 6500P, and vision-related quality of life was evaluated using the 25-item National Eye InstituteVisual Function Questionnaire. One-way and two-way repeated measure analyses of variance were usedfor the comparison. Relationships between respective changes in dry eye syndrome and contrastsensitivity were also analyzed. Results: Daytime contrast sensitivity and ocular pain improved after the administration of red ginseng. Nighttime contrast sensitivity was improved in early or moderate glaucoma. Improved contrast sensitivitywas not associated with improvement in dry eye syndrome. Conclusion: Red ginseng could improve contrast sensitivity and ocular pain in patients with glaucoma. The mechanism underlying improvement in contrast sensitivity appears to be associated with enhancedretinal perfusion or retinal ganglion cell function, but not dry eye syndrome.