• Korean Journal of Materials Research
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• v.28 no.8
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• pp.452-458
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• 2018

This research is conducted to create a functional hydrogel ophthalmic lens containing nanoparticles. Carbon nanoparticles and PEGMEMA are used as additives for the basic combination of HEMA, MA, and MMA, and the materials are copolymerized with EGDMA as the cross-linking agent and AIBN as the thermal initiator. The hydrogel lens is produced using a cast-mold method, and the materials are thermally polymerized at $100^{\circ}C$ for an hour. The polymerized lens sample is hydrated in a 0.9 % saline solution for 24 hours before the optical and physical characteristics of the lens are measured. The refractive index, water content, contact angle, light transmittance, and tensile strength are measured to evaluate the physical and optical characteristics of the hydrogel lens. The refractive index, water content, contact angle, UV-B light transmittance, UV-A light transmittance, visible light transmittance, tensile strength and breaking strength of the hydrogel lens polymer are 1.4019~1.4281, 43.05~51.18 %, $31.95{\sim}68.61^{\circ}$, 21.69~58.11 %, 35.59~84.26 %, 45.85~88.06 %, 0.1075~0.1649 kgf and 0.1520~0.2250 kgf, respectively. The results demonstrate an increase in refractive index, tensile strength and breaking strength and a decrease in contact angle and light transmittance. Furthermore, the visible light transmissibility is significantly increased at PEG 10 %. It is clear that this material can be used for high-performance ophthalmic lenses with wettability, ultraviolet ray blocking effect, and tensile strength.

• Korean Journal of Environmental Agriculture
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• v.30 no.2
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• pp.202-208
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• 2011

BACKGROUD: ${\alpha}$- and ${\beta}$- Endosulfan isomers of endosulfan, an endocrine disrupting chemical, are widely used cyclodiene organochlorine pesticide in worldwide, and it has widespread application in agriculture and can contaminate river-system as runoff from soil or aerial deposition METHOD AND RESULTS: In this study, an attempt was made to isolate an endosulfan degrading fungus from endosulfan-polluted agricultural soil. Through repetitive enrichment and successive subculture in media containing endosulfan and its metabolites as the sole carbon source, a fungus designated KEF-1 was isolated. Based on phylogenetic analysis, strain KEF-1 was assigned to the genus Eutypella. Also, the ITS (internal transcribed spacer) sequences of KEF-1 were submitted to GenBank under accession number EF581006. In potato dextrose broth containing 8 ${\mu}g$/mL endosulfan, strain KEF-1 completely degraded the endosulfanin 12 days. CONCLUSION: These results suggested that Eutypella sp. KEF-1 has potential as a biocatalyst for endosulfan bioremediation

• Journal of the Optical Society of Korea
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• v.16 no.4
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• pp.418-424
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• 2012

The purpose of this study was to assess repeatability and reliability of a new phoria test as compared to established phoria tests and to assess the possibility of mobile or online testing using the auto-flashed presentation. Near dissociated phoria was measured using the von Graefe method, the Howell card test, the modified Thorington test, and a new dichromatic card test (Red-Blue Phoria card test; RBP card test) on 109 subjects. The inter-examiner difference and test-retest difference were calculated. With the auto-flashed presentation of the RBP card test, near dissociated phoria was measured and the intraclass correlation coefficient and test-retest repeatability was assessed on 26 subjects. The variation in inter-examiner repeatability was the smallest for the modified Thorington test (+3.1/-2.6). The RBP card test was +3.0/-3.1, the Howell card test was +3.5/-2.7, and the von Graefe test was +6.2/-6.0. The variation in test-retest repeatability was the smallest for the RBP card test (+0.4/-1.4). The modified Thorington test was +1.3/-1.3, the Howell card test was +1.27/-1.45, and the von Graefe test was +1.59/-2.20. The ICC was 0.919 for the auto-flashed presentation of the RBP card test. The RBP card test is considered a highly repeatable method clinically and can be made a useful application for testing in mobile or online.

• Korean Journal of Materials Research
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• v.28 no.12
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• pp.685-690
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• 2018

In this study, a multifunctional ophthalmic lens material with an electromagnetic shielding effect, high oxygen permeability, and high water content is tested, and its applicability is evaluated. Metal oxide nanoparticles are applied to the ophthalmic lens material for vision correction to shield harmful electromagnetic waves; the pyridine group is used to improve the antibacterial effect; and silicone substituted with urethane and acrylate is employed to increase the oxygen permeability and water content. In addition, multifunctional tinted ophthalmic lens materials are studied using lens materials with an excellent antibacterial effect (2,6-difluoropyridine, 2-fluoro-4-pyridinecarboxylic acid) and functional (UV protection, high wettability) lens materials (2,4-dihydroxy benzophenone, 2-hydroxy-4-(methacryloyloxy)benzophenone). To solve problems such as air bubbles generated during the polymerization process for the manufacturing and turbidity of the lens surface, polymerization conditions in which the defect rate is minimized are determined. The results show that the polymerization temperature and time are most appropriate when they are $110^{\circ}C$ and 40 minutes, respectively. The optimum injection amount of the polymerization solution is 350 ms. The turbid phenomenon that appears in lens processing is improved by 10 to 95 % according to the test time and conditions.

• Journal of Integrative Natural Science
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• v.17 no.3
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• pp.67-73
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• 2024

Hydrophilic contact lens was prepared by dispersing MXene material in a hydrogel mixture, and the purpose of this study was to evaluate its properties as an ophthalmic material. The MXene used in the experiment was manufactured through an etching process using titanium aluminum carbide 312 [Ti3AlC2] and hydrofluoric acid [HF]. For the preparation of hydrophilic contact lenses, 2-hydroxyethyl methacrylate [HEMA], a photoinitiator 2-hydroxy-2-methylpropiophenone [2H2M], and a cross-linker Ethylene glycol dimethacrylate [EGDMA] were used, and UV-rays was irradiated for 50 seconds for photopolymerization. Optical transmittance, refractive index, water content, contact angle, electromagnetic wave shielding ability, and photo-thermal conversion effect were measured to evaluate the physical properties of the manufactured contact lens. Compared to MXene materials, MXene mixed with Dimethyl sulfoxide [DMSO] had superior dispersion ability in organic solvents, and the transparency of the prepared hydrophilic contact lenses was high. MXene did not significantly affect the refractive index and water content, and improved the wettability of the contact lens. In addition, the MXene material used as an additive showed electromagnetic wave shielding ability and photo-thermal conversion effect based on its excellent electrical conductivity. It is judged that the mixture using MXene as an additive can be used as a functional contact lens material for electromagnetic wave shielding and ocular photo-thermal therapy.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.2
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• pp.27-30
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• 2009

Purpose: Transmittance at UV-visible spectra range was measured to confirm the effect of wet/dry state of commercially available SCL on human eyes. Method: Commercially available five SCLs fabricated by different materials were selected to measure optical properties according to humidity. Results: A relatively high transmittance above about 80% in the visible spectra range of the SCLs were observed. In the UV spectra range, the wet samples showed higher transmittance than those dried except an unusual case. Conclusions: All the samples having a high optical properties in the visible spectra range exhibit a high transmittance in the UV region. Further research will be needed to develop new materials having a sharp absorption edge in the UV spectra range.

• BMB Reports
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• v.42 no.12
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• pp.800-805
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• 2009

This study investigated the effect of subconjunctival injections of bevacizumab, an anti-VEGF antibody, on processes involved in corneal wound healing after alkali burn injury. Mice were divided into three groups: Group 1 was the saline-treated control, group 2 received subconjunctival injection of bevacizumab 1hr after injury and group 3 received bevacizumab 1 hr and 4 days after injury. Cornea neovascularization and opacity were observed using a slit lamp microscope. Corneal repair was assessed through histological analysis and immunostaining for CD31, $\alpha$-SMA, collagen I, and TGF-$\beta$2 7 days post-injury. In group 3, injection of bevacizumab significantly lowered neovascularization and improved corneal transparency. Immunostaining analysis demonstrated a reduction in CD31, $\alpha$-SMA and TGF-$\beta$2 levels in stroma compared to group 1. These results indicate that bevacizumab may be useful in reducing neovascularization and improving corneal transparency following corneal alkali burn injury by accelerating regeneration of the basement membrane.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.1
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• pp.105-115
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• 2004

In developed and industrialized countries life expectancy has increased significantly over the past century. As a consequence, the proportion of elderly individuals in these countries has also enlarged with the resulting increased burden on health care providers. In many developing countries the problem of age related and other eye disorders has far outstripped the ability to manage them. Accordingly, the World Health Organization (WHO) has introduced an initiative: Vision 2020 - The Right to Sight, with the objective of eliminating preventable blindness by the year 2020. This paper reviews the broad range of conditions involving external and internal structures of the eye and also the effects of aging on visual functions. It is hoped that this will provide a stimulus for increased study of these disorders, improved clinical diagnosis, and an enhanced interest and role in contributing to the objectives of the WHO and the World Council of Optometry with respect to early diagnosis, prevention and management of the diseases and disorders of the eye that are more prevalent in old age.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.3
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• pp.273-281
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• 2011

Purpose: In order to provide the fundamental information for the design development of RGP lenses and its clinical prescription, the corneal types of Korean twenties were analyzed according to corneal shapes, astigmatic degree, and the certain distance from the corneal apex. Methods: Corneal types of total 252 eyes in 20s were firstly classified, then their corneal radii from the certain distance from the corneal apex were measured by corneal topography and further analyzed based on the astigmatic degree. Results: Korean 20s' corneal types were classified as 14.3%(36 eyes) of round, 31.3%(79 eyes) of oval, 28.6%(72 eyes) of symmetric bow tie, 17.5%(44 eyes) of asymmetric bow tie, 8.3%(21 eyes) of irregular shapes. The round and oval typed corneas had mild astigmatic degree whereas the higher astigmatic degree in symmetric and asymmetric bow tie typed corneas were shown. The relative corneal radii of round and oval typed corneas at each distance from corneal apex were shown to consistently increase regardless of astigmatic degrees when they measured at certain distances from the corneal apex. However, the relative corneal radii of symmetric and asymmetric bow tie typed corneas within 1.0-1.5mm from the corneal apex were decreased, which showed steeper slope than it within 1.0 mm and somewhat different based on astigmatic degrees. Bigger change of corneal radii outer 3.5 mm from the corneal apex in symmetric bow tie typed corneas with astigmatism of 1.50-2.00 D and 2.25-2.75 D appeared. Conclusions: The consideration of radial change from the central cornea to peripheral cornea is necessary for manufacturing RGP lens and its prescription since they showed different change in corneal radii by corneal patterns and astigmatic degrees.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.3
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• pp.229-235
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• 2011

Purpose: The present study was performed to evaluate the safety of ophthalmic lenses in domestic market since eyeglasses wearers could be exposed to the negligent accident by damaged ophthalmic lenses. Method: Totally, 160 ophthalmic lenses (NK55, ${n_{d}}$ = 1.56) with the refractive powers of -3D, -6D, +3D, +6D manufactured by 4 companies in domestic market were evaluated using drop ball test. In accordance with FDA standard, steel ball (~16 g) was freely dropped on these ophthalmic lenses from 127 cm high and the surfaces of lenses were observed. Results: From the study, center thicknesses of NK55 ophthalmic lenses manufactured by 4 different companies showed somewhat different numbers even though the lenses had the same refractive index and powers. All convex lenses of +3D, +6D were evaluated as the safe lenses since there was no damage such as crack and broken found on the lens surfaces after drop ball testing. However, some noticeable broken was shown on the surfaces of concave lenses with relatively thinner center thickness. Especially, 59(73.8%) of total 80 concave lenses with the refractive power of -3D and -6D classified as unacceptable lenses to FDA standard. Conclusions: From the results, the negligent accident by damaged ophthalmic lenses should be considered as well as the correction of visual acuity, design and price when customers purchase eyeglasses. Thus, the enforcement regulation like drop ball testing of uncut ophthalmic lens could be suggested to guarantee the safety of ophthalmic lenses in domestic market.