• Korean Journal of Materials Research
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• v.31 no.8
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• pp.427-432
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• 2021

This study uses silicone monomer, DMA, crosslinking agent EGDMA, and initiator AIBN as a basic combination to prepare hydrogel lenses using fluorine-based perfluoro polyether and iron oxide and zinc oxide nanoparticles as additives. After manufacturing the lens using iron oxide nanoparticles and zinc oxide nanoparticles, the optical, physical properties, and polymerization stability are evaluated to investigate the possibility of application as a functional hydrogel lens material. As a result of this experiment, it is found that the addition of the wetting material containing fluorine changes the surface energy of the produced hydrogel lens, thereby improving the wettability. Also, the addition of iron oxide and zinc oxide nanoparticles satisfies the basic hydrogel ophthalmic lens properties and slightly increases the UV blocking performance; it also increases the tensile strength by improving the durability of the hydrogel lens. The polymerization stability of the nanoparticles evaluated through the eluate test is found to be excellent. Therefore, it is judged that these materials can be used in various conditions as high functional hydrogel lens material.

• Journal of the Korean Chemical Society
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• v.60 no.4
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• pp.261-266
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• 2016

The major physical characteristics of macromolecules used in silicone hydrogel ophthalmic lenses include optical transmittance, oxygen permeability, water content, and refractive index. For the preparation of highly functional silicone hydrogel lens materials, two silicone monomers were used in the presence of 2-hydroxyethyl methacrylate (HEMA) and hydroxypropyl methacrylate (HPMA). The samples containing HEMA and HPMA had oxygen transmissibility (Dk) values in the range of 73.38–50.98 × 10^-11 (cm²/s) (mLO₂/mL×mmHg) and 71.94–42.80 × 10^-11 (cm²/s) (mLO₂/mL×mmHg), respectively. Furthermore, the water contents of samples containing HEMA and HPMA were in the range of 32.73–34.67% and 31.94–33.74%, respectively, and the refractive indices were in the range of 1.4348–1.4364 and 1.4385–1.4407, respectively. Thus, silicone monomers containing HEMA and HPMA are expected to be useful for fabricating high-oxygen-permeability silicon hydrogel ophthalmic lenses.

• 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 Korean Clinical Health Science
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• v.5 no.4
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• pp.1021-1025
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• 2017

Purpose: Changes in corneal thickness after wearing hydrogel lens and silicone-hydrogel lens with different oxygen transmission rates wew syudied. Methods: Experiments were performed on 11 subjects(22 eyes). corneal thickness was measured after wearing contact lenses for 8 hours. Corneal thickness was measured using ORB Scan II(ver. 3.14) Results: In the results of the corneal thickness measurement by direction, in the case of the hydrogel-tor lens, the center thickness was $33.63{\mu}m$, the nasal was $34.29{\mu}m$, the temporal was $27.17{\mu}m$, the inferior was $27.17{\mu}m$, the superior was $18.90{\mu}m$, and change rates were 6.28%, 5.71%, 5.40%, 4.75% and 3.09%, respectively. In the results of the corneal thickness measurement by diameter, in the case of the hydrogel-tor lens, the center was $33.63{\mu}m$, the mid-peripheral was $28.19{\mu}m$, the peripheral was $24.18{\mu}m$, and change rates were 6.28%, 4.76%, and 3.79%, respectively. Conclusions: The hydrogel lenses with relatively low oxygen transmission rates resulted in a significant increase in thickness over the entire cornea compared to silicon-hydrogel lenses with high oxygen transmission rates.

• 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.17 no.4
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• pp.389-394
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• 2012

Purpose: The purpose of this study was to examine the corneal topographical changes associated with the wearing of everted silicone hydrogel soft lenses. Methods: The shape and fluorescein pattern of everted silicone hydrogel lenses were investigated. The subject wore the silicone hydrogel everted lenses overnight for 8 hours. Objective refractive error and corneal shape were evaluated at baseline, 1, 2, 3, 5, and 7 days after lens wearing and 1,2,3, and 4 days after discontinuation of lens wear. Results: The Fluorescein pattern of everted silicone hydrogel lenses was similar to the reverse geometry lenses with pressure profile. Objective refractive error(sphere power) and corneal refractive power were decreased and corneal shape had changed during the everted silicone hydrogel lenses wear and recovered during the 4 days of discontinuation. Subject experienced no discomfort associated with the everted silicone hydrogel lenses. Conclusions: It appears that everted silicone hydrogel lenses are capable of inducing significant changes in corneal topography, with overnight wear. Further study must be done to help understand these changes to develop a predictable and effective way of using soft contact lenses for corneal reshaping.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.2
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• pp.151-156
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• 2015

Purpose: This study has been compared the degree of corneal edema arising from the material of the lens after wearing the recommended wearing time for the contact lens. Methods: For the study, 43 adults of 77 eyes who did not use drugs and have not any disease participated. Three types of lenses including narafilcon A, HEMA, and silicone hydrogel material regular replaceable lenses were used. Central corneal thickness was measured before and after 8 hours from wearing lenses using Pentacam. The degree of corneal edema was determined by the difference before and after wearing. Results: The average corneal edema of narafilcon A, HEMA material lens, and silicone hydrogel material regular replaceable lens were $2.36{\pm}6.15{\mu}m(Mean{\pm}SD)$, $23.61{\pm}10.71{\mu}m$, $18.25{\pm}8.64{\mu}m$, respectively. The central corneal thickness after wearing narafilcon A was not statistically significant with the central corneal thickness before wearing the lens. Central corneal thickness before and after wearing HEMA material lens and silicone hydrogel material regular replaceable lens were statistically significant. Conclusions: The amount of corneal edema induced by silicone hydrogel material regular replaceable lens was no statistically significant difference to the amount of corneal edema induced by HEMA material lens, but there was significant difference to narafilcon A. Therefore, it is judged to be careful not to exceed the recommended wearing time depending on the composition of the 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.17 no.1
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• pp.83-89
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• 2012

Purpose: This article was to study the optical and surface properties of soft contact lenses (SCL) exposed to eye make-ups. Methods: Rates of the light transmission of etafilcon A (HEMA based hydrogel lens) and lotrafilcon B (silicone based hydrogel lens) exposed to four different cosmetics over time were investigated. After cleansed with multi-purpose solution (MPS), rates of the light transmission and surface change of lens that were exposed to the cosmetics for 7 consecutive days were analyzed. Results: Visible light transmissions of all lenses exposed to cosmetics decreased to 93.35% (HEMA based hydrogel lens) and 90% (silicone based hydrogel lens) compared with those of the fresh SCLs, such as 97.8% and 96.4%, respectively. It was found that cosmetic residues from powder eye shadow and mascara attached to the lenses were not removed completely when cleansed with MPS. Especially with silicone based hydrogel lens, we found a decrease in visible light transmission of the lens and noticeable particles on lens surface imaged by SEM. Conclusions: Depending on types of eye make-ups and contact lens materials, make-ups were not completely eliminated with current cleansing methods and that caused a decrease in optical property and a change in surface property of the lenses.

• 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.