• Journal of the Optical Society of Korea
• /
• v.17 no.2
• /
• pp.219-223
• /
• 2013

The purpose of this study was to determine the relationship between the spherical equivalent visual acuity (VA) and uncorrected astigmatism. On 108 emmetropic eyes, the spherical equivalent VA was measured for cross cylindrical lens (CC lens)-induced astigmatic eyes and the VA-astigmatism relation determined. On 158 astigmatic eyes, the spherical equivalent VA and corrected astigmatism were measured and the measured values were compared with the calculated values from the VA-astigmatism relation by correlation coefficient analysis. Subsequent to that, the relationship between spherical equivalent VA and uncorrected astigmatism was made. The relationship was fitted for an exponential equation. Correlation coefficient between calculated values by equation and measured values for astigmatic eyes was 0.991 (p<0.01). The relationship between the spherical equivalent VA and the uncorrected astigmatism was decided as follows (spherical equivalent VA / uncorrected astigmatism): 1.0 / 0.25 D, 0.9 / 0.50 D, 0.8 / 0.75 D, 0.7 / 1.00 D, 0.6 / 1.25 D, 0.5 / 1.50 D, 0.4 / 2.00 D, 0.3 / 2.50 D, 0.2 / 3.00 D, 0.1 / 4.00 D, and 0.05 / 4.75 D. In conclusion, the relationship table devised from this study is a useful reference for predicting uncorrected astigmatism by measurement of decimal VA in spherical equivalent.

• Journal of Korean Ophthalmic Optics Society
• /
• v.16 no.3
• /
• pp.351-356
• /
• 2011

Purpose: The most common symptoms of eyes on VDT syndrome and symptoms-related the factors were investigated. Methods: Self-questionnaire for VDT syndrome was done with 250 teachers from 1st to 15th October, 2010, and the data from 231 teachers (68 male, 163 female) was statistically analyzed to find the factors related to ocular symptoms. Results: The most common ocular symptom on VDT syndrome was 'feeling of eyes fatigue', and the factors which have correlation significantly to ocular symptoms were regular exercise, ages, VDT work time, and regular resting. Conclusions: Taking a rest and regular exercise contribute to relieve the ocular symptoms related to VDT syndrome.

• Journal of Convergence Society for SMB
• /
• v.6 no.4
• /
• pp.85-91
• /
• 2016

This study is to research the tear film stability for 48 eyes, agreed the purpose of study, didn't have no contact lens wearing and were tested all two times in a day. Their visual acuity was more than 0.8, corrective visual acuity more than 0.8, the fattest K-reading, apical corneal radius, was in 7.40~8.40mm, corneal astigment was less than 1.00D and orthophoria. The tests, tear scope test, tear film break up time test(TBUT) and schirmer test order, were performed their functions before and after their working at interval of 6 hours over. The tearscope test results was no difference, TBUT was no difference, although 1.2 seconds more in the afternoon, shcirmer test was decreased 2.0mm in the afternoon.

• Journal of Korean Ophthalmic Optics Society
• /
• v.9 no.2
• /
• pp.241-249
• /
• 2004

Since 1989 the number of nationally licensed ophthalmic and refracting opticians in Korea have increased. Currently, they are being educated in four universities, twenty six colleges and three graduate programs. It is innevitable that the growth of optometric education in Korea will be progressively influnced by worldwide influnces such as the World Council of Optometry(WCO), the World Health Organization (WHO), and the World Trade Organization(WTO). However, currently no standards for optometric education exist in Korea. Thus, the Korean Professional Councils of Ophthalmic Optics(KPCOO) must develope and provide standards for optometric education programs.

• Journal of Integrative Natural Science
• /
• v.11 no.1
• /
• pp.39-43
• /
• 2018

Poly(hydroxyethyl methacrylate)-based hydrogels were surface-functionalized with spiropyran (SP) derivatives to obtain photochromic contact lenses. The contact lens reversibly changes from colorless to purple as response to UV light since colorless ring-closed SP state converts to purple ring-opened merocyanine (MC) state under UV light irradiation. The purple contact lens emits red light at 640 nm. Importantly, the presence of SP segments did not significantly affect the equilibrium water content (EWC) of the lens. SP-functionalized hydrogel lenses may find potential applications in developing light-adaptive ophthalmic materials.

• Korean Journal of Optics and Photonics
• /
• v.24 no.5
• /
• pp.217-223
• /
• 2013

White light MTF(Modulation Transter Function)s of biconvex trial lenses from 10 to 20 diopter (D) were represented as a function of angular frequency and visual acuity, and then they were compared with AIM(Aerial Image Modulation) curves. All of the biconvex trial lenses evaluated in on-axis mode had MTF performance that could resolve Landolt's ring up to visual acuity 2.0. However, in a half field angle of five degrees, the trial lens of 10 diopters was able to resolve Landolt's ring up to visual acuity 0.9, and that of 20 diopter only up to visual acuity 0.8. This means that the trial lenses in the case of a half field angle of five degrees do not have sufficient resolution to measure visual acuity by 1.0.

• Current Optics and Photonics
• /
• v.6 no.2
• /
• pp.196-201
• /
• 2022

Collagen fibers tens of nanometers in size, which constitute most of the corneal volume of the human eye, are layered in a uniform direction, and adjacent fiber layers are arranged at an angle of 90° to each other. According to the results of this study, the transmittance at 45° of interlayer rotation angle is highest, and higher than that of the 90° body structure. The transmittance is examined, concerning the polarization state of the incident light; circularly polarized light case shows higher transmittance than linearly polarized. Through this, a simulation to confirm the deformed structure of collagen fibers, which show higher transmittance than the anatomical structure of the cornea, is attempted.

• Current Optics and Photonics
• /
• v.4 no.2
• /
• pp.141-147
• /
• 2020

To understand the cause of the high light transmittance of the human eye, the optical effects of the collagen fibers of the stroma layer, which constitute the majority of the cornea, were analyzed. These collagen fibers, approximately 20 nm in diameter, have a regular arrangement. Accordingly, the optical properties of the collagen fibers and the fiber layer were analyzed by simulation. A standing wave was formed in the incident space by the overlapping incident light and the light reflected by the plate. In addition, it was confirmed that when the collagen fibers are arranged in a layer, the light transmittance periodically changes, depending on the number of fiber layers. The standing wave was formed in the incident space, and the light's intensity distribution was changed by the nanoscale collagen fibers in the section with the collagen layer, which affected the transmittance. To explain this phenomenon, the collagen fiber was defined as a second light source, and an attempt was made to describe the simulation results in terms of overlap of the incident light with the light emitted from the collagen fiber.

• Korean Journal of Materials Research
• /
• v.28 no.12
• /
• pp.696-701
• /
• 2018

This study is carried out to evaluate the commercial feasibility of the room temperature and thermal polymerization method as a lens manufacturing method. All samples are found to be transparent after polymerization, thereby indicating that their physical and surface properties are suitable for hydrogel ophthalmic lenses. The optical and physical properties of the lenses are compared. The water content of the samples that are prepared via a room temperature polymerization process decreases with the addition of MMA as compared to the water content of the samples that are prepared via thermal polymerization. When MMA and DMA are used as an additive for improving functionality, the wettability of the lenses increases. By measuring the AFM, the surface roughness is shown to improve more than MMA and DMA. Therefore, it is judged to be an appropriate process for manufacturing hydrogel lenses with high functionality.

• Journal of the Korean Chemical Society
• /
• v.61 no.3
• /
• pp.97-103
• /
• 2017

In this study, the functional hydrogel ophthalmic lens containing tungsten oxide nanoparticles, 2,4-dihydroxy benzophenone and 2-hydroxy-4-(methacryloyloxy) benzophenone were manufactured. HEMA (2-hydroxyethyl methacrylate), MMA (methyl methacrylate), AA(acrylic acid), the cross-linker EGDMA (ethylene glycol dimethacrylate), the initiator AIBN (azobisisobutyronitrile) and the functional additives including tungsten oxide nanoparticles, 2,4-dihydroxy benzophenone, and 2-hydroxy-4-(methacryloyloxy) benzophenone were used respectively. The measurements of water content and refractive index of the sample was decreased and increased, respectively. And also, the UV transmittance of produced lens containing 2,4-dihydroxy benzophenone, 2-hydroxy-4-(methacryloyloxy) benzophenone and tungsten oxide nanoparticles was measured. Based on the results of this study, it is judged that the performance improvement increased over time when 2-hydroxy-4-(methacryloyloxy) benzophenone was used as an additive, while the use of tungsten oxide nanoparticles influenced on blue-ray-blocking effect of the hydrophilic lens.