• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11b
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• pp.43-48
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• 2004

Undoped and $Co^{2+}$-doped $CaGa_2S_4$, $CaGa_2Se_4$, $CaIn_2S_4$. and $CaIn_2Se_4$ single crystals were grown by using the chemical transport reaction method The temperature dependence of the optical energy gap was well fitted by the Varshni equation. In the Co2+ - doped $CaGa_2S_4$, $CaGa_2Se_4$, $CaIn_2S_4$, and $CaIn_2Se_4$ single crystals, two groups of impurity optical absorption peaks due to Co2+ sited in a Td symmetry were observed in the wavelength regions of 600 900 nm and 1350 1950 nm at 11 K.耀

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.2
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• pp.233-239
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• 2012

Purpose: In the study, the change of protein and lipid deposits on soft contact lens by drinking was investigated. Methods: Fifty male subjects wearing soft contact lens were surveyed whether they felt any discomfort induced by drinking or not. Further, 32 male subjects who has no ocular disease drank 190 mL alcohol. The protein and lipid deposits on soft contact lens (etafilcon A material) of subjects were measured after 4 hours later and compared with those of non-drinking subject. Results: When subjects drink alcohol with soft contact lens on, 58% of subjects answered they experienced the change of lens awareness such as stiffness, blurry sight, dryness and so on. The protein deposit on soft contact lens increased an average of $59.3{\mu}g/lens$ by drinking and the case of more than double in protein deposit was reached in 9 eyes. However, the protein deposited on soft contact lens was lysozyme which was unchanged by drinking. The amounts of cholesterol and methyl oleate after drinking were 85.5% (p=0.25) and 52.6% (p=0.002) of non-drinking's indicating some change of lipid deposit on soft contact lens by drinking. Conclusions: The results showed the composition of protein and lipid deposited on soft contact lens was changed due to drinking. Thus, it is suggested that wearing soft contact lens when drinking might be one of the reasons to feel discomfort.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.1
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• pp.55-60
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• 2010

Purpose: We investigated the changes of plastic lens after etching of coating films by comparing uncoated lens. Methods: CR-39, middle index and high index lenses of 0 (zero) diopter were etched at $80^{\circ}C$ and room temperature using a coating remover, and then changes of refractive power, transmittance and surface morphology were investigated. Results: There were no differences in refractive power and transmittance between uncoated and etched lenses. The etching rate was similar in both CR-39 and middle index lens, but in the case of high index lens, it was slower and less steady than the others. From the SEM observation of lens surface, etching damage was found out on the surface of etched lens. It was shown the least damage in middle index lens but the most damage in high index lens. Conclusions: If the etching of coating films is demanded on condition that the surface of ophthalmic lenses are not damaged, a using of most adequate coating remover based on lens material should be considered, and a caution for proper etching conditions is required.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.3
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• pp.45-50
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• 2008

Purpose: A soft contact lens was manufactured by adding naringin known as natural anti-bacterial material to resin solution. With solution eluted from manufactured contact lens, we examined its optical properties, physical and chemical states of naringin in the polymer, and elution properties. Methods: The soft contact lens with naringin was synthesized by bulk polymerization method. IR spectrum and HPLC were used to define the bonding type of naringin itself in the soft contact lens contained naringin, elution process of naringin to the saline solution, and the amount of naringin solution eluted from the lens with elapsed time. Results: Naringin was continuously eluted with constant concentration from the soft contact lens for about a month and the structure ofnaringin which is eluted was as same as before it was added to resin solution. Any change in optical properties such as transmittance couldn't be found. Bonding state and the structure of naringin in contact lens were explained with IR spectrum and HPLC results. Conclusions: In the contact lens with naringin, naringin remained in the contact lens bonding with weak hydrogen bonding and/or van der Waals force between naringin and polymer. Naringin was continuously eluted from the contact lens contained naringin during about 1 month. Even after 1 month, it showed that the concentration of the naringin eluted was approximately 10 ppm in a day. From the results, adding naringin to the soft contact lens resin is very effective method for manufacturing the soft contact lens which has anti-bacterial function for a period of time.

• Journal of Integrative Natural Science
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• v.13 no.1
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• pp.13-18
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• 2020

This study used cerium iron hydroxide nanoparticle with HEMA (2-hydroxyethyl methacrylate), the cross-linker EGDMA (ethylene glycol dimethacrylate), NVP (N-vinyl-2-pyrrolidone) and the initiator AIBN (azobisisobutyronitrile) for copolymerization. Also, the physical properties of the prepared lenses were compared, and their applicability as polymers for ophthalmic materials was experimented. The results of the measurement showed that the UV blocking rate and the wettability increased with the cerium iron hydroxide nanoparticles addition ratio, and the refractive index and water content were not affected. Thus, the produced copolymer is expected to be useful as a functional contact lens material while satisfying the basic physical properties of the hydrogel contact lens.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.4
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• pp.339-346
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• 2010

Purpose: The study was performed to compare the difference of non-invasive tear break-up time (NIBUT) with alignment or steep fitting of soft contact lens in normal and dry eyes. Methods: Total 40 eyes (aged 20~30 years) were classified to the normal (n=20) or dry eye group (n=20) by the diagnosis methods for dry eyes and worn soft contact lens (polymacon material) with alignment or steep fitting. NIBUTs of lens wearers were separately measured at the points of before wearing, immediately after wearing and after stabilization of tear film. Results: With alignment fitting, averaged NIBUT in the dry eye group after stabilization of tear film was not significantly different from that of the normal eye group. However, averaged NIBUTs in the normal and dry eyes had significant difference when measured immediately after lens wearing. However, the number of eyes having NIBUT less than 4.0 second was 30% higher compared to the number of normal eyes with steep fitting when measured immediately after wearing. Some shorten NIBUT in dry eyes with steep fitting was also shown after stabilization of tear film. Conclusions: These results suggest that wearing soft contact lens in dry eyes differently affect tear film compared to normal eyes. Thus, dry eyes need more advertent fitting for contact lens wearing because of unstable tear film.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.2
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• pp.125-131
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• 2015

Purpose: The effect of pigmentation in circle contact lens on lens wearers' tear film stability was investigated in this study. Methods: Non-invasive tear film break-up times of 54 normal eyes before and after lens wearing in twenties and the portion of first tear breakup were measured. The frontal and back surface roughness of circle contact lens was further observed with a scanning electron microscope. The clear lens which was made of hilafilcon B and circle contact lenses which were made of hilafilcon B, polymacon and copolymer of HEMA NVP were tested. Results: Non-invasive tear film breakup time was significantly reduced compared with it before lens wearing. In some case, statistically significant difference in tear film breakup time was also observed between circle contact lenses. The tear file break-up was usually early started in lower than upper portion, and in temporal than nasal portion although there was variation in the lens material. The tear film break-up of circle contact lenses made of hilafilcon B was more commonly observed in peripheral portion(pigmented area) compared with clear contact lens made of same material. Conclusions: The present study revealed that the stability of tear film was affected by wearing circle contact lens and the result seems to be used as the basis for the problem solving that can occur due to the pigmentation when wearing circle contact lens.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.2
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• pp.217-224
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• 2014

Purpose: This study was conducted to compare and analyze the accommodative system (accommodative response and accommodative lag) according to the material and font size of near visual media that we often encounter in daily life. Methods: Forty adult men and women aged 20 to 30 who not had specific ocular diseases and refractive surgery experience were examined to measure and compare the accommodative response according to the material of near visual media (print paper, newspaper, magazine, the I-Phone, LCD monitor) and font size (6, 8, 10, 12) by using both eyes open-view auto-refractometer. Results: The accommodative stimulus was $2.28{\pm}0.11D$ and the accommodative response was $1.66{\pm}0.30D$. The accommodative lag namely the difference between accommodative stimulus and accommodative response was $0.62{\pm}0.28D$. The accommodative response according to material of visual media using LCD monitor was $1.35{\pm}0.26D$ (p=0.00) and using the I-Phone was $1.55{\pm}0.25D$ (p=0.04). Both of them were statistically significant lower. The accommodative lag using LCD monitor was $0.93{\pm}0.24D$ (p=0.00) and using the I-Phone was $0.73{\pm}0.25D$ (p=0.04) and they were statistically significant higher. The accommodative response and accommodative lag according to font size were not statistically significant (p>0.05). Conclusions: During near working, the accommodative system was more affected by material than font size of visual media. Especially, visual media of non-luminous material (print paper, newspaper, magazine) are considered fewer burdens on eyes than luminous material (I-Phone, LCD monitor) in terms of accommodative system.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.1
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• pp.83-89
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• 2005

The results that research industrial competitive power of about two hundreds frames manufactures were as follows. First, It's researched that frames industry of Daegu will be worse and worse, and 79 percent of inquiry manufactures in export and 58 percent of them in the domestic demand prospects to be worse. Second, it is analyzed that the commercial profits in 2004 was more decreased to 16.5 percent than 2002. Therefore it is studied that they will be diminished to 5---- comparing with last year by a fall in the exchange rate of the won dollar, in the export unit cost and a raise of raw material price. Third, it is researched that most competitive countries of Daegu glasses manufactures is China and the mext county is japan, ltuly and hik. Fourth, It is studied that average price of glasses of Daegu during last three years(2002~2004) was more disadvantageous than China and Hong Kong, but was more profitable than Italy and Japan by the examination that when Korea is 100, China is 82, Hong Kong 89, Italy 112, Japan 114. Fifth, It is investigated that the average of production cost in Daegu is more disadvantageous than that of China and Hong Kong but is more profitable that of Italy and Japan by the study that when average production cost of Korea is 100, that of China is 78 and that of Hong Kong 89, that of Italy 114. Sixth, It is studied that the Average personal expense of Daegu is much more disadvantageous than that of China and more profitable than Japan and Italy by the analysis that when Korea is 100, China is 74, Hong Kong 98, Japan 112, Italy 113. Seventh, It is analyzed that technique, quality, design of Daegu are more advantageous than those of China, are equal with those of Hong Kong. Eighth, It is studied that Daegu still lags behind more four and five years than developed countries and goes more oheod four years than developing countries.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.4
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• pp.383-390
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• 2011

Purpose: The present study was conducted to investigate whether refractive powers of soft contact lenses were induced by the deposition of tear proteins when wearing soft contact lenses. Methods: The soft contact lenses (material: etafilcon A, hilafilcon A and comfilcon A) with refractive powers of -1.00 D, -3.00 D, -5.00 D and -7.00 D were incubated in artificial tear for 1 day, 3 days, 5 days, 7 days and 14 days, respectively. After incubation, their refractive powers were measured by wet cell method with an auto-lens meter and their protein deposited on the lenses was determined by the method of Lowry. Results: Among three types of soft contact lenses, the most protein deposition was detected in ionic etafilcon A lens material and significant change of its refractive power was manifested. In other words, refractive powers of etafilcon A lenses firstly decreased after 1 day incubation in artificial tear and then gradually increased with increasing incubation period again. The observed change in refractive powers of all diopters of etafilcon A material was beyond the scope of standard error and bigger in the lens with lower optical power. On the other hand, non-ionic hilafilcon A showed less protein deposition as much as about 20% in etafilacon A and statistically significant increase of refractive powers with increasing incubation period in artificial tear. The change in refractive power of hilafilcon A was also beyond the scope of the standard of error when incubating in artificial tear and greater in the lens with lower diopter. The least protein deposit was shown in silicone hydrogel lens material, comfilcon A as approximately 10% of it in etafilcon A, indicating less change in refractive power within the standard range of error. Conclusions: The large change of refractive powers that was beyond the scope of standard error by the deposition of tear proteins on soft contact lenses was differently detected depending on lens materials in the current study. Thus, the deposition of tear proteins induced by longer period of lens wearing may be one of the causes that induces blurred vision, suggesting that soft contact lens wearers with the amount of tear proteins may need to choose proper lens material.