Hydrophilic surface modification of poly(methyl methacrylate)-based ocular prostheses using poly(ethylene glycol) grafting

Ko, JaeSang,Cho, Kanghee,Han, Sang Won,Sung, Hyung Kyung,Baek, Seung Woon,Koh, Won-Gun,Yoon, Jin Sook Elsevier 2017 Colloids and surfaces Biointerfaces Vol.158 No.-

<P><B>Abstract</B></P> <P>Ocular prostheses are custom-made polymeric inserts that can be placed in anophthalmic sockets for cosmetic rehabilitation. Prosthetic eye wearers have reduced tear amount, and they often experience dry eye symptoms including dryness, irritation, discomfort, and discharge. Most modern ocular prostheses are made of poly(methyl methacrylate) (PMMA), which is highly hydrophobic. Previous research has shown that improving the wettability of contact lens materials decreases its wearers discomfort by increasing lubrication. Therefore, hydrophilic modification of PMMA-based ocular prostheses might also improve patient discomfort by improving lubrication. We modified the surfaces of PMMA-based ocular prostheses using poly(ethylene glycol) (PEG), which is hydrophilic. To do this, we used two strategies. One was a “grafting from” method, whereby PEG was polymerized from the PMMA surface. The other was a “grafting to” method, which involved PEG being covalently bonded to an amine-functionalized PMMA surface. Assessments involving the water contact angle, ellipsometry, and X-ray photoelectron spectroscopy indicated that PEG was successfully introduced to the PMMA surfaces using both strategies. Scanning electron microscopy and atomic force microscopy images revealed that neither strategy caused clinically significant alterations in the PMMA surface morphology. In vitro bacterial adhesion assessments showed that the hydrophilic modifications effectively reduced bacterial adhesion without inducing cytotoxicity. These results imply that hydrophilic surface modifications of conventional ocular prostheses may decrease patient discomfort and ocular prosthesis-related infections.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Surfaces of PMMA-based ocular prosthesis were modified via PEG grafting. </LI> <LI> The hydrophilic surface modifications effectively inhibited bacterial adhesion. </LI> <LI> These modifications of ocular prostheses may decrease discomfort and infections. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Delayed onset <i>Mycobacterium intracellulare</i> keratitis after laser in situ keratomileusis : A case report and literature review

Ko, JaeSang,Kim, Se Kyung,Yong, Dong Eun,Kim, Tae-im,Kim, Eung Kweon Wolters Kluwer Health 2017 Medicine Vol.96 No.51

<P><B>Abstract</B></P><P><B>Rationale:</B></P><P>Infectious keratitis is a relatively uncommon but potentially sight-threatening complication of laser in situ keratomileusis (LASIK). Mycobacterial keratitis is usually regarded as late onset keratitis among post-LASIK keratitis. There has been no documented case of <I>Mycobacterium intracellulare</I> post-LASIK keratitis of a long-latent period.</P><P><B>Patient concerns:</B></P><P>A 36-year-old man was referred to our out-patient clinic, for persistent corneal epithelial defect with intrastromal infiltration. He had undergone uneventful bilateral LASIK procedure 4 years before. He complained decreased vision, accompanied by ocular pain, photophobia, and redness in his left eye for 7 months.</P><P><B>Diagnosis:</B></P><P>Lamellar keratectomy was taken using femtosecond laser. Bacterial culture with sequenced bacterial 16s ribosomal DNA confirmed the organism to be <I>M intracellulare</I>.</P><P><B>Interventions:</B></P><P>After 3 months of administration of topical clarithromycin, amikacin, and moxifloxacin, the corneal epithelial defect was resolved and the infiltration was much improved. However, newly developed diffuse haziness with surrounding granular infiltration in the central cornea was noted. Drug toxicity was suspected and topical moxifloxacin was discontinued, resulting in resolution of the diffuse haze with infiltration.</P><P><B>Outcome:</B></P><P>The patient was followed up regularly without medication thereafter and recurrence was not found for 7 years.</P><P><B>Lessons:</B></P><P>This case presents the first case of <I>M intracellulare</I> keratitis after LASIK. LASIK surgeons should aware that post-LASIK keratitis can develop long after the operation and careful suspicion of infectious disease with meticulous diagnostic test is needed.</P>

Kimura Disease with Lacrimal Sac and Nasolacrimal Duct Involvement: A Case Report

Hyeong Ju Byeon(Hyeong Ju Byeon),JaeSang Ko(JaeSang Ko),Jun Yong Kim(Jun Yong Kim),Jin Sook Yoon(Jin Sook Yoon) 대한안과학회 2023 Korean Journal of Ophthalmology Vol.37 No.3

MF Based Arc Signal detection for SWG linked Wastewater Treatment Plant

Eunyoung Ko,Jaesang Cha,Juyoung Lee,Jintae Kim,Jaekwon Shin,Jawan Gu,Myongchul Shin 보안공학연구지원센터(IJMUE) 2011 International Journal of Multimedia and Ubiquitous Vol.6 No.4

Serum Selenium Levels in Patients with Graves Disease: Associations with Clinical Activity and Severity in a Retrospective Case-control Study

Tae Hwan Kim,JaeSang Ko,Bo Ram Kim,Dong Yeob Shin,Eun Jig Lee,Jin Sook Yoon 대한안과학회 2022 Korean Journal of Ophthalmology Vol.36 No.1

Purpose: To compare serum selenium levels in Graves patients and non-Graves control participants and to evaluate associationsbetween serum selenium levels and clinical features of Graves orbitopathy (GO). Methods: We conducted a single-center, retrospective case-control study among 33 patients with Graves disease withoutGO (GD), 31 patients with diagnosed GO, and 27 unaffected healthy participants enrolled between 2013 and 2020 at SeveranceHospital. We compared serum selenium concentrations between the GD, GO, and healthy control groups, and analyzedassociations between serum selenium and GO patients’ clinical activity scores, severity (assessed through modified NOSPECSscores), and other clinical features using multivariate linear regression analysis. Results: Mean serum selenium levels were 109.30 ± 16.39, 111.39 ± 14.04, and 126.09 ± 21.09 ng/mL in GO patients, GDpatients, and healthy control participants, respectively. Mean serum selenium levels in Graves patients with and without orbitopathywere significantly lower than those in the healthy control group (p < 0.05), and mean selenium levels were slightlylower in GO than those in GD patients (p = 0.594). Serum selenium levels were significantly lower in GO patients with eyelidretraction than in patients without retraction (p = 0.038). However, serum selenium levels were not associated with clinicalactivity scores and modified NOSPECS scores (p = 0.241 and 0.801, respectively). Conclusions: Serum selenium levels were significantly lower in Graves patients with or without GO, compared to non-Gravescontrol participants. Selenium levels were not associated with clinical activity scores or NOSPECS scores, though we observedan association with eyelid retraction.

Meibomian Gland Dysfunction Associated With Periocular Radiotherapy

Woo, Young Jun,Ko, JaeSang,Ji, Yong Woo,Kim, Tae-im,Yoon, Jin Sook Masson Pub. USA 2017 Cornea Vol.36 No.12

PURPOSE:: To investigate the influence of periocular radiotherapy on meibomian glands. METHODS:: We evaluated 28 patients (40 eyes) who received radiotherapy (RT group) for conjunctival or orbital lymphoma and 30 age-matched control subjects (60 eyes). Subjects underwent slit-lamp examination of the eyelids, Schirmer test, meibography, and evaluation of tear film breakup time (TBUT), Ocular Surface Disease Index (OSDI) scores, meibomian glands evaluation (meiboscore, meibum expressibility, and lid margin abnormality scores), and tear film lipid layer thickness using an ocular surface interferometer. These parameters were compared between subjects in the RT and control groups. RESULTS:: Meiboscores as well as meibum expressibility and OSDI scores in the RT group were significantly higher compared with those in the control group (1.6 ± 0.9 vs. 0.4 ± 0.6, 1.6 ± 1.0 vs. 0.2 ± 0.4, and 48.1 ± 21.4 vs. 6.2 ± 4.4, respectively, P < 0.001, all), whereas the Schirmer value (9.2 ± 5.1 vs. 12.3 ± 5.2, P = 0.004), TBUT (4.2 ± 2.5 vs. 6.4 ± 2.6, P = 0.001), and lipid layer thickness (61.0 ± 29.3 vs. 85.2 ± 20.0, P < 0.001) in the RT group were lower compared with those in the control group. The percentage of meibomian gland dropout was significantly correlated with age (P = 0.025) and total radiation dose (P = 0.012), regardless of the target location of irradiation. Even low-dose irradiated eyes (<30 Gy) exhibited significantly higher meiboscores (P < 0.001) and shorter TBUT (P = 0.005) compared with control eyes. CONCLUSIONS:: Eyes that received periocular radiotherapy exhibited relatively high tear film instability induced by meibomian gland dysfunction, contributing to the high severity of dry eye symptoms.

Prevalence of Ocular Hypertension and Glaucoma as Well as Associated Factors in Graves’ Orbitopathy

Kim, Ji Won,Ko, JaeSang,Woo, Young Jun,Bae, Hyoung Won,Yoon, Jin Sook Raven Press 2018 Journal of glaucoma Vol.27 No.5

PURPOSE:: The purpose of this study was to determine the prevalence of ocular hypertension (OHT) and open-angle glaucoma (OAG) in patients with Graves’ orbitopathy (GO) and to investigate the associations between clinical features of the disease and the prevalence of OHT and OAG. METHODS:: A cross-sectional analytic study was conducted among a total of 1128 patients with GO. A complete ophthalmic examination was performed, including intraocular pressure, optic disc photography, visual field testing using a Humphrey visual field analyzer, and retinal nerve fiber layer thickness measured by optical coherence tomography. The results were analyzed by univariate and multivariate logistic regression. RESULTS:: A 6.8% prevalence of OHT (77/1128) and a 1.6% prevalence of OAG (18/1128) were observed. When considering only patients older than 40 years, the prevalence of OHT and OAG was 9.5% and 3.4%, respectively. Twenty-nine of the 1128 patients (2.6%) developed compressive optic neuropathy. Of the factors evaluated, male sex [odds ratio (OR), 1.83; 95% confidence interval (CI), 1.08-3.10], duration of GO (6 to 24 mo; OR, 2.08; 95% CI, 1.17-3.71; 24 to 60 mo; OR, 3.45; 95% CI, 1.66-7.18), clinical activity score ≥3 (OR, 1.76; 95% CI, 1.03-3.01), extraocular muscle involvement (OR, 4.65; 95% CI, 2.54-8.50), and lid retraction (OR, 2.17; 95% CI, 1.19-3.96) were associated with the prevalence of OHT in GO. The prevalence of OAG was associated with male sex (OR, 4.29; 95% CI, 1.60-11.51) and duration of GO (≥60 mo; OR, 4.28; 95% CI, 1.11-16.47). CONCLUSIONS:: The prevalence of OHT in patients with GO was higher and the prevalence of OAG was similar to that in the general population.

A Pilot Clinical Study of Ocular Prosthesis Fabricated by Three-dimensional Printing and Sublimation Technique

Bo Ram Kim,So Hyun Kim,JaeSang Ko,Seung Woon Baek,Yung Kyung Park,Yoon Jung Kim,Jin Sook Yoon 대한안과학회 2021 Korean Journal of Ophthalmology Vol.35 No.1

Purpose: We sought to evaluate the safety and effectiveness of patient-specific ocular prostheses produced by three-dimensional(3D) printing and the sublimation technique. A comparison with prostheses produced using manual manufacturingmethods was then performed. Methods: To confirm the biological and physiochemical safety, cytotoxicity, systemic acute toxicity, intradermal reaction,and skin sensitization tests were conducted according to the International Organization for Standardization guidelines. Thecompressive strength of the prostheses was also tested. Further, a case series of three patients who wore the 3D printedprostheses for more than eight hours daily for 4 weeks was executed. Self-assessments by these individuals using a questionnaireand safety evaluations focusing on the occurrence of conjunctival inflammation or allergic reactions according to theCornea and Contact Lens Research Unit criteria by slit-lamp examination and similarity assessment were completed. Results: The 3D printed ocular prostheses met the necessary qualifications per the biological and physiochemical safety tests,showing the absence of cytotoxicity, acute systemic toxicity, intradermal reactivity, and skin-sensitizing potency. Also, therewas no difference in strength test results between previous ocular prostheses and the 3D printed ones. Self-assessment bythe patients yielded satisfactory results, with no significant difference in the level of satisfaction reported for the 3D printedand previous handmade ocular prostheses. The 3D printed prosthesis did not trigger any side effects in the conjunctival sacand showed similar objective findings with respect to the color of the iris, sclera, and vessel patterns. Conclusions: Our study confirms the biologic and physiochemical safety of 3D-printed ocular prostheses created using computer-aided design technology and a sublimation technique. The patients’ questionnaires and the judgment of the ophthalmologists/ocularists showed that the 3D printed ocular prosthesis was acceptable in function and appearance through a caseseries report.

차량용 고 분해능 디지털 MEMS 가속도센서 시스템 IC 개발

유광호(Kwangho Yoo),고형호(Hyoungho Ko),이아라(Ahra Lee),임재상(Jaesang Lim),이상윤(Sang-Yoon Lee),정덕균(Deog-Kyoon Jeong),박민하(Minha Park),장현수(Hyunsu Jang),이정표(Jeongpyo Lee),조동일(Dong-il Dan Cho) 한국자동차공학회 2006 한국자동차공학회 Symposium Vol.- No.-

This paper presents design, fabrication and measurement of a high resolution digital microelectromechanical systems (MEMS) accelerometer system IC. This system IC consists of a MEMS sensing element and a high resolution digital readout circuit. The MEMS sensing element is fabricated using the sacrificial/bulk micromachining (SBM) process. In order to protect the sensing element from environmental changes, wafer level hermetic packaging(WLHP) process is performed. The developed readout circuit offers 32-bit resolution using an 1-bit, 4th-order ΣΔ modulator and a digital decimator/demodulator. The proposed system IC provides a 128-㎐, 32-bit digital output with ±5g dynamic range, 0.52% nonlinearity, and 1.6*10? count/g scale factor.

선체회전을 고려한 교량-선박충돌해석

이계희(Lee Gye-Hee),고재상(Ko JaeSang),김대환(Kim DaeHwan),조태원(Jo TaeWon) 한국구조물진단유지관리학회 2007 한국구조물진단학회 학술발표회논문집 Vol.11 No.1

In this paper, the methodology for the collision analysis of bridge-vessel was proposed with consideration of the rotational vessel DOF. And it was examined numerically by the estimation of structural responses of the bridge and the vessel. The rotational DOF of vessel was represented by the rotational buoyancy spring. The global responses of bridge were estimated from spring-mass model driven from the first lateral vibration mode. The local structural responses of bridge were considered by the addition of local shell model. The numerical example showed the adequateness and feasibility of the proposed method.