• 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.18 no.4
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• pp.405-411
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• 2013

Purpose: In this study, the mounting status of trial case lens was investigated. Methods: We measured distances between geometric center of lens mount and optical center of lens and angle deviations between axis mark on lens and real axis using arbitrary trial case lens sets distributed in Korea, and then, compared those results with international standards. Results: In some of lenses, the prismatic power on geometric center of lens mount and the angle deviations between axis mark and real axis of cylindrical lens were out of tolerance according international standards. Conclusions: The more precise control of the manufacturing process and more thorough quality control for trial case lenses will be required to offer an accurate vision test.

• Biomedical Science Letters
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• v.18 no.3
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• pp.324-327
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• 2012

Acanthamoeba is a free-living amoeba that causes human infections, and recently the incidence of amoebic keratitis has increased among contact lens wearers. In order to investigate Acanthamoeba contamination of contact lens storage cases, a short survey was performed on 57 contact lens wearers, and Acanthamoeba was found in one contact lens storage case. To diagnose Acanthamoeba, the 18s small subunit ribosomal DNA (18s rDNA) gene was amplified by polymerase chain reaction (PCR), and subsequently, the isolate was identified as A. lugdunensis. This species was originally isolated from a freshwater pool in France, and was reported recently to be a cause of amoebic keratitis. This observation indicates the need for a large survey to investigate the extent of Acanthamoeba contamination, and suggests that contact lens wearers be aware of the importance of hygiene and of the implications of Acanthamoeba infection.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.2
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• pp.77-83
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• 2006

We have studied the astigmatism according to the bevel position and the tilting(pantoscopic) angle of decentered spectacle lens for prism prescription. For prism prescription, generally we make a general spectacle lens into decentered spectacle lens. At this time the bevel position of decentered lens is a important matter, because the difference between optic axis and visual axis occur aberrations. Using the calculation we find that the case that the axis of bevel rotation band passes the front curvature center of (+) lens has a smaller astigmatism than the case that the axis of bevel rotation band passes the rear curvature center of (+) lens and that the case that the axis of bevel rotation band passes the rear curvature center of (-) lens has a smaller astigmatism than the case that the axis of bevel rotation band passes the front curvature center of (-) lens. We find the lens with higher refraction index has a smaller astigmatism.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.4
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• pp.321-334
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• 2012

Purpose: In this study, the distribution and differences in refractive powers on trial case lenses were investigated. Methods: We measured refractive powers at optical center and periphery using 4 trial case lens sets. According to international standards, the distribution and uniformity in refractive powers were investigated. Results: The lens shapes were different in different kinds of trial case lenses and some of lenses were out of tolerance according international standards. In some cases, the power differences were found between front and back side as well as between optical center and peripheral regions and also the cylindrical power on spherical lens and spherical power on the cylindrical lens were measured. Conclusions: Trial case lens are used to assess the refractive error, therefore, more precise control of the manufacturing process for trial case lenses and more thorough quality control will be required to offer an accurate vision test. More careful attention in using trial case lens is also required.

• Korean Journal of Optics and Photonics
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• v.5 no.2
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• pp.204-211
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• 1994

Micro array lens systems are designed for a faximile or copy machine. The array type is hexagonal. Diameter of a lens is 0.16 mm and the distance of the center of the nearest neighbor is 0.192 mm. The magnitude of the lens system is 1:1. Working distane is 10.55 mm and the spot size is less than 0.04 mm radius on axis and 0.20 mm off-axis in case of single layer system. Working distance is 7.90 mm and the spot size is less than 0.07 mm radius on axis and 0.09 mm radius off axis in case of double layer system. Performance of single layer micro array lens system and double layer micro array lens system are compared with the characteristics of the ray fans.y fans.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.2
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• pp.135-145
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• 2011

Purpose: This study was conducted to investigate the actual condition of caring soft contact lens cases and the change in contamination level of lens cases by wearing and storage period of soft contact lens. Methods: The actual condition of caring soft lens cases was surveyed with sixty-three of contact lens wearers. Soft contact lenses were worn for 1, 3, 7 and 14 days, and the lenses were separately stored in 12 lens cases for 1, 3 and 7 days. The contamination level of lens cases was determined by counting the numbers of microorganisms, gram negative bacteria and fungi. Results: Only 14% of survey answerers cleaned their lens cases with a brush, rinsed and dried them upside down before next usage of lens case when those lenses were kept for a long time. Furthermore, 54% of total answerers just kept soft contact lens in the case without changing the multipurpose solution. Microorganisms, gram negative bacteria and fungi were detected in lens cases even when soft contact lens were kept for 1 day in the lens case after wearing for 1 day and cleaning it with multipurpose solution. The numbers of microorganisms, gram negative bacteria and fungi in lens cases increased with storage periods of soft contact lens, and also contamination level of lens cases was increased in accordance with wearing period of lens. In the lens cases without changing multipurpose solution, the numbers of microorganisms, gram negative bacteria and fungi increased with storage period of lens with statistical significance. Conclusions: This study showed that lens wearers' concerns on caring contact lens case were not satisfactory. As the result, the contamination of lens cases was related to increase of lens wearing and storage periods suggesting that the proper instruction and education for lens wearers are required.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.132-136
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• 2002

Optical collimating lenses are play a role as maintenance parallel light and as a kind of optical collimating lens, there is Ball lenses, GRIN-rod lenses, spherical lenses and aspherical lenses etc. but recently GRIN lens has monopolized a market. The performance of optical collimator depended on the coupling efficiency. In this paper, we were compared and analyzed to be measured values of coupling efficiency with respect to optical working distance using GRIN rod lenses and spherical lenses. In the case of GRIN lenses with a beam size of 420 ${\mu}{\textrm}{m}$, the minimum coupling efficiency was obtained to a measured value of 0.15 ㏈ and in the case of spherical lenses was obtained to a measured value of 0.12 ㏈ on the same condition. In results, we found that a performance of spherical lenses be better as compared with a that of GRIN lens.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.2
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• pp.202-210
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• 2011

The fabrication method of aspheric lens is changed from machining to press molding so as to improve the productivity. In the case of the press molding method, the temperature control of the molding die is most important, because the temperature of each molding die determines the quality of lens. But any practical method for direct measuring of the lens temperature and the die internal temperature is yet unknown. Besides, in the case of the press molding system in which the heating and pressing and cooing of a die is done at separate work stations, the lens productivity of the system for small lens is yet too low. The paper shows an improved structure of convective sequential system, the lens productivity of which is three times as many as the conventional convective system. To know the die internal temperature, numerical results are given using ANSYS. A new convective sequential system is developed and tested. Finally, the Taguchi method is applied in order to optimize the setting conditions of individual work station of the system.

• 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.