• 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.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.3
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• pp.261-270
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• 2013

Purpose: Adsorption properties of lysozyme and albumin according to physiochemical properties of commercial contact lens classified with the FDA categories and a contact lens fabricated in the laboratory were investigated. Methods: The contact lens were prepared using HEMA(2-hydroxyethyl methacrylate) and TRIM(3-(trimethoxysilyl) propyl methacrylate) in a cast mold. Artificial tears containing lysozyme and albumin were prepared. We measured the amounts of protein adsorbed on the each lenses with varying adsorbed time (48 hour) and the pH range (6, 6.8, 7.4, 8.2, 9) of artificial tear. Amount of the proteins absorbed on the contact lenses were measured by using HPLC. Results: Time to reach the equilibrium of protein adsorption for silicone hydrogel lens was taken longer than hydrogel lens. The amount of adsorbed both lysozyme and albumin at equilibrium were greater for the hydrogel lens than the silicone hydrogel lens, and larger for the ionic lens than the non-ionic lens. Lysozyme was more adsorbed on the higher water content of contact lens, whereas albumin was more adsorbed on the lower water content of contact lens. Only lysozyme was adsorbed on the Group IV hydrogel lens of ionic higher water content. The adsorption of protein on contact lens increased with pH of artificial tears as close to the isoelectric point of each protein. Conclusions: The adsorption amount of lysozyme is more affected by the ionic strength of the contact lens surface than the water content of contact lens. Albumin adsorption is more affected by water content than the ionic strength of the contact lens surface. For the adsorption of proteins on the silicone hydrogel lens, the pore size, determined both by the number of Si atoms and the chemical structure of the silicone-containing monomers, as well as the polarity of contact lens should be also considered.

• Journal of the Korea Convergence Society
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• v.9 no.1
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• pp.393-403
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• 2018

Although the use of silicone hydrogel contact lenses which are known to have high oxygen transmissibility is increasing, they are being sold without any product labeling of physical properties such as water content and oxygen transmissibility. To analyze the physical properties such as the water content and oxygen transmissibility of approved silicone hydrogel contact lenses, this study collected and analyzed the approval information published on the KFDA website. Of 68 cases of domestic silicone hydrogel contact lenses analyzed in this study, 61 cases (89.7%) did not meet the international standard for oxygen permeability. This is because lenses that are not different from hydrogel contact lenses were submitted for approval as silicone hydrogel contact lenses because there is no domestic standard for silicone hydrogel contact lenses. In future, besides the information published on the website, analysis of the physical properties of a wide variety of actual silicone hydrogel contact lenses on the market is required.

• 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 Korean Ophthalmic Optics Society
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• v.11 no.3
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• pp.259-265
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• 2006

We polymerized material of AA(Acrylic acid) and BMA(butyl methacrylate) to make up for the weak points of hydrogel contact lens. The synthesis process of silicone synthesis is as follows. Acrylate-PDMS(Polydimethylsiloxane)-Urethane prepolymer was composed after Diisocynate reacted with HEMA(2-hydroxyethylmethacrylate) under the catalyst and it reacted again with bis(hydroxyalkyl) terminated poly(dimethylsiloxane) with high oxygen transmissibility characteristics. HEMA(2-hydroxyethylmethacrylate) was used to make prepolymer that can be polymerized and the urethane was used to improve elasticity and oxygen transmissibility, copolymerization was performed with conventional hydrogel contact lens materials to make silicone hydrogel contact lens with higher oxygen transmissibility. For manufacturing of contact lens, We added BMA(Butyl methacrylate) with better elasticity and flexibility, and AA(Acrylic acid) with higher moisturizing to used contact lens materials. AIBN (Azobis2-methylpropionitrile) as initiator and EGDMA(Ethylene Glycol Dimethacrylat) as crosslinking agent were used and the lens with higher oxygen transmissibility and better moisturizing were manufactured complying with basic contact lens properties, which have several combination trial of each monomer characteristics. Compounding SN which included SILICONE, HEMA, NVP and EGDMA etc was showed by swelling ratio of 9.38% and water content of 23.7%. SN was showed by swelling ratio of 9.38%, water content of 23.7% and a visible ray transmissibility of 89%. SB which added BMA in the SN was showed by swelling ratio of 12.50%, water content of 18.56% and a visible ray transmissibility of 88%. SAB which added both AA and BMA in the SN was showed by swelling ratio of 8.33%, water content of 12.93% and a visible ray transmissibility of 88%.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.3
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• pp.271-277
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• 2013

Purpose: The purpose was to study the corneal refractive power changes associated with the wearing of everted silicone hydrogel soft lenses. Methods: The corneal refractive power and corneal astigmatism were measured using corneal topographer (CT-1000, Shin-nippon Co., Japan) for checking change of corneal refractive power and objective refractive error was measured by auto-refractometer (Natural vision-K 5001, Shin-nippon Co., Japan). We measured at baseline and 1 week after lens wearing. Results: The correcting of corneal refractive power could be effective in low myopia. It's more effective to the higher power of greatest meridian of cornea and the more corneal astigmatism. 73% of subjects' refractive error was decrease less than 1 D and 17% of the subjects had an reverse effect (increase) occurs. The reduction of objective refractive error was more effective when cornea refractive power was great or corneal astigmatism was much. Conclusions: Pressure which the everted silicone hydrogel lens to the cornea could be caused. It occurred as the degrees of corneal power, corneal astigmatism and objective refractive error differences. Selection of an appropriate subject is important considering difficulty of changing the parameters of the lens.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.2
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• pp.143-149
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• 2006

The purpose of this study is synthesizing silicone polymer which is used the material of contact lens and solving the problems of water content and light transmittance for gas permeable contact lens. We used NVP, MMA, HEMA monomer for polymerization and EGDMA as cross linking regent. Also, we polymerized with a several formulation arrangement for the best condition as contact lens. After that. we measured water content and light transmittance by each sample which was polymerized. We polymerized the silicone polymer which is simultaneously pursued by the transparent and water content of the material and measured their physical nature of each sample on this study.

• 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.

• Polymer(Korea)
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• v.38 no.2
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• pp.220-224
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• 2014

Protein adsorption kinetics was studied with the amount of proteins adsorbed to contact lens hydrogels over time scales. Hydroxyethylmethacrylate (HEMA) and silicone hydrogels were dipped in protein solutions (albumin or IgG) and adsorption amounts were measured over time scales. The amount of protein adsorbed to both hydrogel types increased rapidly in 10 min, and remained consistently in 90 min. Decreasing interfacial energetics was taken slowly up to an hour in spite of rapid diffusion of protein molecules. This is due to the fact that water deprivation from three dimensional interphase initially formed by protein diffusion took over an hour. Interpretation of adsorption kinetics on contact lens hydrogels was discussed with understanding of relationship between surface energy and protein adsorption capacity.

• Polymer(Korea)
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• v.33 no.2
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• pp.169-174
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• 2009

Silicone hydrogels incorporated with poly(ethylene glycol)(PEG) were prepared and characterized to evaluate the effects of PEG on contact lenses. The silicone hydrogels were copolymerized with methacryloxypropyl tris(trimethylsiloxy) silane (TRIS), methyl methacrylate (MMA), N,N-dimethyl acrylamide (DMA) and PEG-containing monomers such as poly(ethylene glycol) methyl ether methacrylate (PEG- MEM). The silicone hydrogels were characterized using Fourier transform infrared spectroscopy (FT-IR), electron spectroscopy of chemical analysis (ESCA), and scanning electron microscopy (SEM). Water absorbance, water contact angle and light transmittance of the silicone hydrogels were evaluated. The experiments of protein adsorption were also carried out to evaluate the protein adsorption in tears. The peak intensity of C-O bond was increased by the incorporation of PEG-containing monomers and thus PEG incorporation into silicone hydrogels could be confirmed. Phase separation was not shown by the SEM observation of the cross-section of silicone hydrogels. Water absorbancy was increased, while water contact angle and light transmittance were decreased with increasing incorporation of the PEG-containing monomers. The absorption of proteins in tears, albumin, lysozyme and $\gamma$-globulin, on the surface of silicone hydrogels was decreased with increasing incorporation of the PEG-containing monomers.