• KSBB Journal
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• v.16 no.1
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• pp.82-86
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• 2001

Glyco-acrylate and methacrylate were synthesized by lipase-catalyzed glycosylation of acrylic acid, methacrylic acid and their vinyl esters with $\beta$-methyl fructoside and glycerol in t-butanol as a reaction medium. At the optimum conditions for enzymatic glycosylation of acrylic acid and vinyl methacrylate, we attained up to 80% conversion for glyco-acrylate from acrylic acid and 90% conversion for glyco-methacrylate from vinyl methacrylate. The polymerizable glyco-acrylates and methacrylate have biomedical application as hydrophilic monomers and hydration modifiers to be use for hydrogel contact lens formulation.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.4
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• pp.43-54
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• 2007

Silicone hydrogel contact lenses developed as a continuous-wear modality are now used as a daily-wear contact lenses. The purpose of this study was to investigate the clinical performance in a group of successful long-term wearers of conventional hydrogel contact lenses when refitted with daily wear $O_2OPTIX$ silicone hydrogel lenses. Sixty-two wearers ($30.7{\pm}19.9$ months of prior lens wear) among sixty-five soft lens wearers refitted with $O_2OPTIX$ silicone hydrogel lenses were participated in this study finally. Subjective symptoms were scored and objective signs were graded using CCLRU scales during the study period. 98% of subjects were successfully refitted with the one base curve of $O_2OPTIX$, and 33.9% of subjects were needed more or less lens powers compared with their habitual lenses. Subjects reported a concurrent reduction in dryness, redness and tiredness compared with their habitual lenses and both subjective and objective evaluations showed that dryness, tiredness, itchiness, bulbar and limbal hyperemia were decreased and significantly decreased particularly for those subjects with greater baseline symptoms (p<0.0001). But corneal staining was increased and was seen in many subjects during the study (p<0.0001). Refitting existing soft contact lens wearers with silicone hydrogel contact lens could result in a decreased in dryness, redness and tiredness, particularly more effective for those subjects with greater baseline of those symptoms. When patients using conventional hydrogel materials switch to a silicone hydrogel material, the potential for increased corneal staining should be considered and over-refraction should be needed to give a best vision.

• Korean Journal of Materials Research
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• v.33 no.1
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• pp.1-7
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• 2023

The physical and antibacterial properties of ophthalmic lenses fabricated by copolymerization with hydrogel monomers using two types of graphene were measured, and their usability as contact lens materials was analyzed. For polymerization, silicone monomers, including SID-OH, 3-(methacryloxy)propyl tris(trimethylsiloxy)silane, and decamethylcyclopentasiloxane, were used, and N,N-dimethylacetamide, ethylene glycol dimethacrylate as a crosslinking agent, and azobisisobutyronitrile as an initiator were added. Also, graphene oxide nanoparticle (GON) and graphene nanoplate (GNP) were used as an additive, and the physical properties of the lenses fabricated after copolymerization were evaluated. The fabricated lenses satisfied the basic physical properties of general hydrogel contact lenses and showed the characteristics of lenses with high water content, and the disadvantage of very weak durability, due to low tensile strength. However, it was confirmed that the tensile strength and antibacterial properties were greatly improved by adding GON and GNP. With GON, the oxygen permeability and refractive index of the fabricated lenses were slightly improved. Therefore, it was determined that the graphene materials used in this study can be used in various ways as a contact lens material.

• Journal of Biomedical Engineering Research
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• v.9 no.1
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• pp.67-72
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• 1988

Poly (HPMA/NVP) hydrogel was synthesized according to the composition and the con- centration of the crosslinking agent. The swelling degree of the P(HPMA/NVP) hydrogel decreased with increasing of P(HPMA) composition and crosslinking agent. The glass transi- tion and softening temperatures of the P(HPMA/NVP) increased with increasing of P(HPMA) composition. The composition of P(HPMA/NVP) : 70/30 and the concentration of the crosslin- king agent of 0.5 wt % gave the optimum condition in the application to the contact lens. There were also adequate in the mechanical, refractive properties and in vivo test in the P(HPMA/ NVP): 70/30 system.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.4
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• pp.381-388
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• 2012

Purpose: In this study, the changes in the shape of silicone hydrogel lenses, dryness of lens and objective/ subjective symptoms that could be induced by repeating dryness of lens and objective/subjective symptoms were investigated. Methods: After drying and rehydrating of silicone hydrogel lenses with different lens material and thickness for 4 times, their overall diameters and base curves were compared. Subjective symptoms, non-invasive tear break-up time (NIBUTs) and blinking rate were evaluated after wearing dehydrated silicone hydrogel lens. Results: Overall diameter and base curve increased in all tested silicone hydrogel lenses by repeating dryness and rehydration. The degree of change in over all diameter and base curve were variable on the material. There were irregular change of lens parameters in thicker lens. When the subjects wore silicone hydrogel lenses after drying and rehydrating, their NIBUTs were decreased and blink rates were increased regardless of lens material or thickness. In addition, repetitive drying of silicone hydrogel lenses affected the lens fitting. Therefore, subjective symptoms such as itching, pain, irritation, foreign body sensation, dryness tended to be increased. Conclusions: The results obtained from the study may suggest to develop durable silicone hydrogel contact lenses against dry environment since the changes in parameters of silicone hydrogel lens and the subjective discomfort were observed after repetitive drying and rehydration.

• Journal of Integrative Natural Science
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• v.8 no.1
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• pp.60-66
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• 2015

The physical and optical properties of polymers with 2-fluoroaniline and 4-fluoroaniline added, which can be used for hydrophilic ophthalmic lenses, were investigated in this study. The UV-blocking properties of 2- and 4-fluoroaniline were also investigated by measuring their UV transmissibility. 2- and 4-Fluoroaniline were used as additives for the basic combination of HEMA, 5% AA, and 1% MMA, and the materials were copolymerized with EGDMA as the cross-linking agent and AIBN as the initiator. The refractive index, water content, optical transmittance, tensile strength, and contact angle were measured to evaluate the physical properties of the produced hydrogel lens. The measured physical properties of the hydrogel contact lens produced with the copolymerized polymer showed a refractive index of 1.425-1.436; a water content of 36.95-44.65%; a visual light transmittance of 66.0-81.0%; a tensile strength of 0.138-0.281 kgf; and a contact angle of $55.02-57.87^{\circ}$. The UV transmissibility was significantly reduced, which indicates that 2-fluoroaniline and 4-fluoroaniline have UV-blocking properties. This study showed that 2- and 4-fluoroaniline are expected to be used as UV-blocking materials in hydrogel ophthalmic lenses whose physical properties, such as their refractive index and water content, do not change.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.3
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• pp.315-322
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• 2014

Purpose: The physical and optical characteristics of hydrophilic tinted contact lens containing titanium silicon oxide nanoparticles and the basic hydrogel contact lens material containing 4-iodoaniline were examined. In this study, the utility of titanium silicon oxide nanoparticles as a UV-blocking material for ophthalmologic devices were investigated by measuring the UV transmittance of the produced polymer. Also, titanium silicon oxide nanoparticles only without the addition of 4-iodoaniline in primary contact lens materials by copolymerizing two groups were compared. Methods: For manufacturing hydrogel lens, HEMA, MA, MMA, 4-iodoaniline and a cross-linker EGDMA were copolymerized in the presence of AIBN as an initiator. Also, the titanium silicon oxide nanoparticles was used as additive. After polymerization the physical properties such as water content, refractive index, contact angle and spectral transmittance of produced contact lenses were measured. Results: Measurement of the physical properties of the copolymerized material showed that the water content, refractive index, UV-B transmittance and contact angle were in the range of 35.01~38.60%, 1.4350~1.4418, $34.15{\sim}57.25^{\circ}$ and 1.0~10.0%, respectively. Titanium silicon oxide nanoparticles is not used as an additive in the experimental group, the results of the measurement showed that the water content, refractive index, contan angle and UV-B transmittance of the hydrogel lens polymer was 34.00~36.80%, 1.4378~1.4420, $40.15{\sim}60.16^{\circ}$ and 1.8~25.0%, respectively. Conclusions: Also, the transmittance for UV light was reduced significantly in combinations containing titanium oxide nanoparticles.

• Journal of Korean Ophthalmic Optics Society
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• v.1 no.1
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• pp.57-63
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• 1996

The microbial contamination in contact lens care systems and conjunctivas of 40 asymptomatic cosmetic soft contact lens wearers was investigated. Patient ages ranged from 19 to 27(mean:22), most of them have used hydrogel contact lenses for less than 1 year, and the ages of lens cases were 1 weeks ~ 3 months (43 %) or 4~6 months (52%). Twenty-seven patients (67%) chemically disinfected their lenses and 8(20 %) used hydrogen peroxide, and 5 used heat to disinfect. Fourteen patients used commercial non-preserved saline, and 26(65%) were using commercial preserved saline. Sixty-two percent of the patients had bacterial contamination of lens case, and 17% had conjunctival contamination. The bacterial contamination rate was highest in lens cases, followed by unpreserved salines, disinfecting chemicals(non-hydrogen peroxide), and conjunctivas. The fungal contamination rate of cases and conjunctivas was 67% and 15%, respectively, and lens case, unpreserved saline, and conjunctiva seemed more susceptible to contamination. The use of hydrogen peroxide for disinfection rather than chemical disinfection was associated remarkabley with decreased contamination of solution itself, and there was no significant difference in contamination rates between hydrogen peroxide care system and other disinfecting systems. Five of lens cases(13%) and 2 conjunctivas(5%) were contaminated with Pseudomonas aeruginosa, and Candida albicans were isolated from 11cases (27%) and 5 conjunctivas (12%). Of the organisms that were contaminated lens cases and conjunctivas, Pseudomonas aeruginosa, Escherichia coli, Candida albicans, and Aspergillus fumigatus were isolated from lens cases, whereas Pseudomonas aeruginosa, Candida albicans, and Aspergillus fumigatus were recorvered from conjunctivas. Fortunately all of the these tested samples showed 0% of Acanthamoeba in this investigation.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.4
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• pp.347-353
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• 2010

Purpose: An in vitro study was conducted to compare the lipid cleaning efficacy of care solutions on balafilcon A silicone hydrogel (SiHy) lens. Methods: Lipid spoilation was performed by incubating balafilcon A SiHy lenses in phosphate buffered saline (PBS) containing oleic acid, oleic acid methyl ester and cholesterol. Spoiled contact lenses rinsed with PBS were cleaned with surfactant cleaner, alcohol containing cleaner and multipurpose solution (MPS) respectively and repetitive spoilation and cleaning was conducted up to 14 times. To observe the cleaning effect of ultrasonic wave on the lipid deposit, each spoiled lens was ultrasonicated and then compared with non-sonicated lens. Lipids deposit on the contact lenses was extracted by methanol:chloroform (1:1, v/v) solution. High performance liquid chromatography was used to analyze and quantify lipid deposit extracts. Results: The effectiveness of alcohol containing surfactant cleaner on the lipid deposits was better than that of surfactant cleaner and MPS, and the cleaning efficacy was significantly higher in the ultrasonic wave treated group. Lipid deposits were not removed completely by contact lens care solutions so that lipid deposits increased continuously and cumulatively. Conclusions: The cleaning efficacy of contact lens care solutions was not satisfactory to remove lipid deposits on the SiHy lens that new cleaning products specially designed for SiHy lenses are needed to develop.

• Journal of Pharmaceutical Investigation
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• v.39 no.2
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• pp.127-131
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• 2009

Hydrogels for medical devices such as hydrophilic dressing, moisturizing healing band, hydrophilic intravenous catheter and soft contact lens were evaluated for their cytotoxicity according to the International Organization for Standardization (ISO) procedures. To test indirect cytotoxicity of hydrogel products, dissolution medium and dissolution condition were selected based on the guideline for medical devices. Cytotoxicity was low in all the case of hydrogel products. Soft contact lens showed no significant difference in dissolution between complete medium and saline. Currently, there is no specific guidelineto test hydrogel for medical devices in Korea with consideration of characteristics of hydrogel. Thus, proper method of cytotoxicity evaluation should be selected depending on the characteristics and usages of hydrogels for medical devices.