• The Korean Journal of Vision Science
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• v.20 no.4
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• pp.569-577
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• 2018

Purpose : The study looked at how effective each group wearing MyoVison lens, MC lens, and Single Vision lensdepending on their parents' myopia condition. Methods : The study observed the changeof spherical equivalent among customers, who visited between January 2010 and December 2016,of an optical shop in Incheon Metropolitan City. And we observed MyoVision 152 eyes, MC Lens 86 eyes and Single Vision lens 270 eyes. This study was conducted using SPSS ver18, which analyzes the changes in average values of MyoVision, MC Lens, and Single Vision for a year.In each group, the differences in the group were compared using the Paired T-test and then one-way ANOVA (post-hoc; Bonferroni) Results : Group-to-group comparisons showed that MyoVision and MC Lens have a shorterinhibition than Single Vision. In particular, MyoVisionand MC Lens showed different relief effects depending on the degree of refraction of parents.When both parents had normal refractive, the change between MyoVision and Single Vision lens was $-0.35{\pm}0.05D$. When the father had a refraction MC lens were $-0.36{\pm}0.14D$ more effective than Single Vision. When only the mother had refraction, the mean value between MyoVision and Single Vision lens was $-0.37{\pm}0.06D$, and the mean between MC lens and Single Vision lens was $-0.38{\pm}0.08D$. And when both parents had refraction problems, the mean value change between MyoVision and Single Vision lens was $-0.28{\pm}0.07D$, and $-0.31{\pm}0.07D$, respectively. Conclusion : MyoVision and MC Lens appeared to have no effect on the functions of mitigating myopia in within group comparisons, but MyoVision and MC Lens showed reducing myopia than Single Vision in between group.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.4
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• pp.45-51
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• 2009

Purpose: The purpose of this study is to compare and analyze the survey results of clinical performance and visual problem, and the survey were carried out before and after of VDT working for 4 hours by wearing functional lens designed for improving VDT syndrome and single-vision lens. Methods: We tested near & far visual acuity, change of spherical equivalent, near point of accommodation, near point of convergence, AC/A ratio, accommodative facility and survey of subjective symptoms to visual problem of before and after VDT working for 4 hours after wearing single-vision lens and functional lens subjected on 30 males and females in the age of 20 to 45. Results: When wearing functional lens comparing to single-vision lens, near visual acuity, near point of accommodation, near point of convergence, and accommodative facility are significantly improved. It is investigated that average scores of 10 items to visual problem after VDT working for 4 hours are 3.63${\pm}$0.75 at single-vision lens and 4.69 ${\pm}$ 0.83 at functional lens, and therefore functional lens is significantly improved. Conclusions: It is thought that functional lens is an excellent lens which helps to improve accommodative function and visual problem after VDT working for 4 hours than single-vision lens.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.1
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• pp.75-84
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• 2013

Purpose: Changes of refractive correction value in different age group were investigated. Regarding the inhibitive effects against myopia progression after wearing reverse geometry contact lenses and myopia control lenses (MC lenses), the effects after wearing single vision lenses were compared. Methods: We organized children between the ages of six and fifteen into three groups by age, and distributed fifty-seven reverse geometry contact lenses, fifty-six MC lenses and seventy-eight single vision lenses among them to be worn. Group 1 consisted of children aged ten and under, Group 2 consisted of children between the ages of eleven and fifteen, and Group 3 represents all of the study participants. The aim of this study was to learn the inhibitive effects against myopia progression attained by changes of refractive correction value and to verify their statistical significance at twelve months and under, thirteen to twenty-four months and twenty-five to thirty-six months. Results: Changes of refractive correction value by each length of use in Group 3 were as follows. For the age group of under twelve months, participants using the reverse geometric contact lens showed no change, while those using the MC or single vision lens had significant changes (P<0.05) of $-0.36{\pm}0.10$ D and $-0.67{\pm}0.52$ D, respectively. Users of all three lens types displayed significant change (P<0.05), in the age group of between thirteen and twenty-four months, of $0.18{\pm}0.49$ D, $0.60{\pm}0.42$ D and $1.37{\pm}0.72$ D for users of the reverse geometry contact lens, the MC lens and the single vision lens, respectively. There were significant changes (P<0.05) of $0.29{\pm}0.61$ D, $0.93{\pm}0.57$ D and $1.72{\pm}0.78$ in the same respective order as the above in the age group of twenty-five to thirty-six months. Refractive correction value showed changes with different age group. Group 1 displayed significant changes (P<0.05) of $0.29{\pm}0.73$ D, $1.07{\pm}0.59$ D and $1.75{\pm}0.74$ D for users of the reverse geometry contact lens, MC lens and single vision lens, respectively, up to thirty-six months of lens wearing; Group 2, also up to thirty-six months, displayed significant changes (P<0.05) of $0.28{\pm}0.42$ D, $0.75{\pm}0.49$ D and $1.70{\pm}0.84$ D in the same respective order, and changes in refractive correction for the age group under ten years was significantly greater (P<0.05) for the age group of eleven and older. Conclusions: The results found in this study demonstrate that there were no changes of refractive correction value for the case of wearing reversing geometry contact lens up to twelve month or less. MC lens showed less changes in variations of visual acuity for all users which might be resulted in inhibiting progression of myoptia. When both reverse geometry contact lens and the MC lens are wearing for the period from 13 to 36 month, both lens showed less changes in variation of visual acuity for all users. The results suggested that the less changes in variation of visual acuity of both lens had an effect on inhibiting progression of myopia.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.1
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• pp.19-26
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• 2012

Purpose: This paper was to study the clinical effects of moderating myopia by comparing the myopia control lens, which was being recently recognized as a method of inhibiting the progression of myopia, with the wearers of single vision lens. Methods: Using 56 subjects between the ages of 8-15 years (112 eyes) with myopia in the areas of City of Daegu and Gyeongsangbuk Province as study subjects, refractive error, axial length, near point of convergence and accommodative near point were measured and compared a total of 3 times at the baseline, after 1-month and after 6-months. Results: For refractive error, suppression and mitigation were seen in the progression of spherical equivalent when MC lens was worn, as compared to using SV lens, and, when axial length MC lens was worn, the axial progression was significantly suppressed and delayed (p < 0.05). The near point of convergence became shorter with the use of MC lens, and the amplitude of convergence was improved when MC lens was worn. Accommodative near point became shorter with the use of MC lens, and focus ability was significantly improved (p <0.05). Conclusions: It was shown that MC lens, compared to SV lens, could alleviate myopia progression in school-age children and youth. It is considered that MC lens can be used as a useful therapy for the inhibition of myopia progression in the increasing number of myopic children and adolescents.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.1
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• pp.103-108
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• 2009

Purpose: The objective of this study is to compare and analyze the wearing status of refractive error correction devices of elders who reside in a city or in a small town district. Methods: Each of opticians from a small town or a city was selected for the study of wearing status of presbyopia correction device for each residential district in units of percentage. with the analysis of the age and gender distributions of the elders, numbers of elderly members, and the kinds of presbyopia correction. Results: The wearing rate of progressive lens was reduced in reverse proportion to the increase of the age for the people of presbyopia in a twon. Pepople in 60s living in a town perferred to wearing bifocal lens, but people of 50~60s preferred to single vision lenses. However, none of people living in a city who is diagnosed as presbyopia had refractive error correction device, and no one used bifical lenses. The progressive lens was mostly used in the people of 40~50s and using rate of those lenses reduced with the age; and single vision lens had the highest rate of in the 40~50s but no one wore it in the 70s. Conclusions: Among the refractive error correction devices, the progressive lens was most widely worn by presbyopia group who is living in a town or a city. In particular, the refractive error correction devices were most preferred in 40~50s of early presbyopia. The highest preference for the progressive lens in the people with the early presbyopia indicates that the wearing rate of the progressive will be increased in future. Therefore, the opportunity of systematic education on the progressive lens should be increased.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.1
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• pp.51-60
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• 2011

Purpose: This study was to investigate visual performance and subjective satisfaction with multifocal soft contact lenses at near works in university students. Methods: In a cross-over study design, 26 students (6 male, 20 female) who did not have any ocular disorder with at least 20/20(1.0) binocular vision were fitted with singlevision lenses (SofLens$^{TM}59$, Bausch + Lomb Co. USA) or multifocal lenses (SofLens Multifocal, Bausch + Lomb Co. USA). After 2 weeks, visual performance assessments included visual acuity, stereoacuity and contrast sensitivity function at distance and near. Near point of accommodation, accommodative facility, near point of convergence, vergence facility and near range of clear vision at near were examined. Students' satisfaction and preference were measured using survey questionaries. Results: Subjects maintained at least 20/20 binocular vision with multifocal and single-vision lenses at distance and near. There was no difference between multifocal and single-vision lenses in stereoacuity, contrast sensitivity function and vergence facility at far and near. The near point of accommodation, accommodative facility, near point of convergence and the near range of clear vision with multifocal lenses were better than single-vision lenses. On the survey questionaries, subjects reported that they preferred and satisfied with multifocal lenses with near works, and single-vision lenses with distance works. Conclusions: The majority of university students preferred multifocal to single vision lenses because multifocal lenses provided better visual performance at near works. This study suggests that multifocal lens is helpful for young adult in prolonged near works.

• Korean Journal of Materials Research
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• v.29 no.12
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• pp.735-740
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• 2019

The purpose of this study is to fabricate an ophthalmic lens by copolymerizing two types of carbon nanotubes and hydrophilic hydrogel lens materials, and to investigate its application as an ophthalmic lens material by analyzing its physical properties and antimicrobial effect. For polymerization, HEMA (2-hydroxyethyl methacrylate), EGDMA (ethylene glycol dimethacrylate), a crosslinking agent, and AIBN (azobisisobutyronitrile), an initiator, are used as a basic combination, and a single-walled carbon nanotube and a single-walled, carboxylic-acid-functionalized carbon nanotube are used as additives. To analyze the physical properties, the water content, refractive index, breaking strength, and antimicrobial effect of the fabricated lenses are measured. The fabricated lenses satisfies all the basic properties of the basic hydrogel ophthalmic lens. The water content increases with increasing amount of additive and decreases with addition of 0.2 % ratio of nanoparticles. The refractive index is inversely proportional to the water content result. As a result of the antimicrobial test of the fabricated lens, the addition of carbon nanotubes shows an excellent antimicrobial effect. Therefore, it is considered that the fabricated lens can be applied as a functional material for basic ophthalmic hydrogel lenses.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.631-632
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• 2006

The assembly of camera lens modules fur the mobile phone has not been automated so far. They are still assembled manually because of high precision of all parts and hard-to-recognize lens by vision camera. In addition, the very short life cycle of the camera phone lens requires flexible and intelligent automation. This study proposes a fast and accurate identification system of the parts by distributing the camera for 4 degree of freedom assembly robot system. Single or multi-cameras can be installed according to the part's image capture and processing mode. It has an agile structure which enables adaptation with the minimal job change. The framework is proposed and the experimental result is shown to prove the effectiveness.

• Animal cells and systems
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• v.7 no.4
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• pp.331-335
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• 2003

Vertebrates with different habitats have different proportions of visual cells, with the rod cells responding to scotopic vision and the cone cells responding to photopic and color vision in their retinas. The present work studied whether the kinds and arrangement patterns of the cone cells and interlocking morphology of the lens were related to the kind of preys and habitats in the genus Zacco. The retinas were observed by a light microscopy using H-E staining method and the interlocking formula of the lens fibers were investigated by a scanning electron microscopy. The interlocking formula of the lens fibers of Z. temmincki is an ' anchor and socket ' connection, and that of Z. platypus is a ' ball and socket ' connection. The cone cells of Z. platypus and Z. temmincki constituted compacted mosaic patterns of row type. Away from the center, the double and single cone cells gradually increased in diameter. Zacco temmincki had identical double cone cells and Z. platypus had non-identical double and single cone cells. The eyes of Z. temminckifeeding on a moving aquatic insects in relative limpid water and swift current of mid and upper stream have better resolution than that of Z. platypus feeding on mainly adhesive algae and some aquatic insects in slightly turbid water of mid stream.

• Current Optics and Photonics
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• v.1 no.5
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• pp.538-543
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• 2017

Progressive addition lenses (PAL) have very wide application in the modern glasses market. The unique progressive surface can make a lens have progressive refractive power, which can meet the human eye's different needs for distance-vision and near-vision. According to the national glasses fabrication standard, the difference between actual optical power after fabrication and nominal design value should be less than 0.1D over the lens effective area. The optical power distribution of PAL is determined directly by the surface. Consequently, the surface processing accuracy requirement is proposed. Beginning from the surface expressions of progressive addition lenses, the relationship equations between the surface sag and optical power distribution are derived. They are demonstrated through tolerance analysis and test of an example progressive addition lens with addition of 2.09D (5.46D-7.55D). The example addition surface is fabricated under given accuracy by a single-point diamond ultra-precision machine. The optical power of the PAL example is tested with a focal-meter after fabrication. The optical power addition difference between test result and design nominal value is 0.09D, which is less than 0.1D. The derived relationship between the surface error and optical power is verified from the PAL example simulation and test result. It can provide theoretical tolerance analysis proof for the PAL surface fabricating process.