• 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.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.2
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• pp.117-122
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• 2011

Purpose: This study analyzed the factors related to adaptation of people who wears progressive lenses glasses for the first time. Methods: 463 presbyopia (Aged 41~78) without any ocular diseases with the progressive lens glasses were prescribed from 2010 to 2011 at B clinic in the Gwangju city. Progressive lenses adaptation were analyzed according to gender, age, distance refractive state, presbyopic addition, progressive lens design, the old glasses, astigmatism type, and anisometropia etc. High, mid and low-adapted groups were categorized as the status of wearing progressive lenses glasses, re-wearing, occasionally wearing and failed to weraing, respectively. Results: Men showed significantly higher adaptation (p=0.02) than women. Presbyopic addition (p=0.05) and progressive lens design (p=0.02) were statistically significant. However, it was found that there was so statistical significance for the factors of age, distance refractive state, the old glasses, astigmatism type, and anisometropia. Conclusions: According to the results of this study, when progressive lenses were prescribed, we should consider for adaptation gender, presbyopic addition, and progressive lens design etc.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.1
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• pp.1-7
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• 2009

Purpose: To improve the quality of Korean progressive addition lenses, we measured the optical and geometrical elements of them and evaluated their qualities. Methods: We have measured the refractive power, the thickness at optical center and prism power for home and foreign progressive addition lenses which were distributed in the domestic market, and then have done a comparative analysis according to international standards. Results: The qualities of Korean progressive addition lens were on an equal footing with famous foreign brand products, but they were out of tolerance in a few cases. Conclusions: The careful attention is required to progressive addition lens, therefore, it is considered that more precise quality control is an essential element to strength the competitiveness of Korean products in the world market.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.2
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• pp.131-135
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• 2006

The purposes of this study is examining a wearing tendency of a progressive multifocal lens. We measured refractive error values using subjective and objective refraction method with subjects in 40-65 ages. Also, we investigated and analyzed distribution of addition power and wearing tendency of progressive multifocal lens. Detected addition powers were ranged of +0.75D - +3.00D. In case of average addition, they were detected with +1.18D in 40's, +1.55D - +1.97D in 50's and +2.38D in above 61's age. The distributions of visual ability at a distant were measured that the hyperopia and hyperopic astigmatism 43%, the myopia and myopic astigmatism characteristic astigmatism 7% appeared highly with 36%. The male who uses the interior aspect multi focal lens with the short-range work were appeared the male 20%, the woman 19%.

• 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.18 no.4
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• pp.399-404
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• 2013

Purpose: This study was to analyse the changes of refractive error and addition in progressive eyeglasses lens wearers. Methods: Data of 244 subjects who have been prescribed progressive eyeglasses lenses were used for analysis. The range of age was between 43~69 old years and they visited the optical shop in Gwangju metropolitan city from 2003 to 2013. According to the refractive state and age, The changes of refractive error and addition was analysed respectively. Results: The changes of distance refractive power by refractive error was showed +0.10 D in emmetropia, +0.07 D in myopia, +0.23 D in hyperopia (p=0.000). The change of addition was showed +0.22 D in emmetropia, +0.29 D in myopia, +0.17 D in hyperopia (p=0.000). The changes of distance power and addition by age was +0.08 D distance refractive power, +0.30 D addition in the group of 40~49 old years, +0.17 D distance refractive power, +0.20 D addition in the group of 50~59 old years and +0.15 D distance refractive power, +0.14 D addition in the group of 60~69 old years (p=0.046, p=0.006). Conclusions: The changes of refractive error and addition of progressive eyeglasses lens wearers in all refractive state and age were gradual increase in the direction (+) diopter.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.50-59
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• 2010

In this paper, two kind of free-form progressive addition lenses (PALs) were designed with Zernike polynomial surface and anatomically accurate finite presbyopic schematic eyes which have aspheric cornea, aspheric GRIN crystalline lens, aspheric retina, and Gaussian apodization factor. Geometrical and diffraction MTFs were used for the optimization process in sequence. 5th orders of Zernike polynomials were used for the evaluation of progression zones of the two examples. The target MTF was set as 0.22 at 100 lp/mm which satisfies the standard visual resolution. These examples were fabricated with a CNC diamond turning machine controlled by slow tool servo (STS). After polishing process, the wavefront aberrations were measured with a laser interferometer on the ten test points across the progression zones and then compared with three current commercially available PALs on the optical performance. Astigmatic aberrations of the examples are very lower than the three selected PALs and have more increased stabilized progressive intermediate zones and near zones. It is expected to give better clear and comfortable distance, intermediate and near visions than other conventional PALs and to improve the adaptability of presbyopic patients to PALs.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1063-1068
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• 2008

A lens system of a camera module for mobile phones is comprised of the composition and design of various shapes of lens. To improve responses such as the modular transfer function (MTF), a lens system should always be constructed by considering uncertainty that can be caused by manufacturing and assembly error. In this study, tolerance optimization using the Latin Hypercube Sampling (LHS) technique is performed. In order to reduce the computational burden of the tolerance optimization process and decrease the influence from numerical noise effectively, we use the Progressive Quadratic Response Surface Modeling (PQRSM), which is one of Sequential Approximate Optimization (SAO) techniques. Using this method, we achieved optimal tolerance for each lens and obtained reliability for satisfying user‘s requirements. In addition, through the design process the manufacturing and assembly cost of a lens system was reduced.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.4
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• pp.471-477
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• 2014

Purpose: We have analyzed the transmittance distribution of the ocular lens using local transmittance microscope to investigate the optical homogeneity of the lens. Methods: The transmittance of the laser which is focused on the surface of the ocular lens was measured by using the photo-detector and lock-in amplifier and analyzed. Multi-coated, uncoated, and progressive lenses were analyzed. Results: In the measurement of the progressive lens and a physical stimulated lens, local transmittance microscopy analysis showed a high degree of match with the measurement results through the optical microscope. In addition, the average value of the transmittance is reduced and the standard deviation was increased in the presence of optical defects. In unstimulated lens, there are a large impact on transmittance whether the anti-reflective coating is presence or absence in both the local transmittance microscopy and general transmittance analysis. Conclusions: The distribution of the transmittance measured by local transmission microscopy were changed when the various stimulus is applied to the lenses. These analyzes by local transmission microscopy can be utilized as a way to evaluate or determine the uniformity of the coating film or lens.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.3
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• pp.247-251
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• 2013

Purpose: To analyse the addition power of new wearer of progressive addition lenses. Methods: Data of 636 subjects who have been prescribed progressive addition lenses as the first time were used for analyse. The range of age for was between 41~78 years old and they visited the optical practice in Gwangju metropolitan city from 2001 to 2013Date of refractive state, gender and age were analysed. Results: The difference of addition by gender was 1.71 D in male and 1.67 D in women. The difference of addition by refractive error was 1.67 D in emmetropic patients and 1.74 D in myopic patients, 1.90 D in hyperopic patients. The difference of addition by age was1.26 D in 41~44 years old sge group, 1.48 D in 45~49 years old age group,1.72 D in 50~54 years old age group 1.84 D in 55~59 years old age group, 2.10 D in 60~64 years old age group and 2.43 D in over 65 years old age group. The difference of addition by diopter in myopic patients was 1.58 D in low myopic patients and 1.48 D in middle myopic patients, 1.67 D in high myopic patients. The difference of addition by axis of astigmatism was 1.80 D in with-the-rule astigmatism, 1.64 D in against-the-rule astigmatism and 1.65 D in oblique astigmatism. Conclusions: The Addition power of progressive lenses were different according to the types of refractive error, astigmatism axis and age.