• The Journal of Natural Sciences
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• v.16 no.1
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• pp.31-37
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• 2005

We have developed an algorithm to determine the position from the image points in a lensmeter with 6-sided prism lens. The positions of the image points which are formed by six prisms depends on the decenter position of a test lens and can be calculated by skew ray tracing. The optical characteristics of the lens meter was analyzed using the Code V program and the positions of the image points was expressed as a function of the decenter position of the test lens. By minimizing the expectation error, we can determine the decenter position position of a test lens from the image positions.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.1
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• pp.31-35
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• 2001

We have studied the auto-lensometer for several years in order to begin korean-made production of it and then developed the auto-lensmeter using with the personal computer. We introduce the most important principal of PSD device and the optical principal of measuring the power of the refraction of the lens by auto-lensometer and also explain the fabrication of the LED optical source system and PSD optical system. Finally, we found the power constant of our auto-lensmeter to be about 30 Diopter/mm.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.1
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• pp.39-46
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• 2010

Purpose: To assess the reliability for measuring the back vertex power of soft contact lenses by dry blotting and wet cell method using an auto-lensmeter. Methods: The soft contact lenses used for measurement were 5 types that were distributed in Korea, and 4 back vertex powers (-1.50D, -3.00D, -6.00D, -9.00D) were used. and repeatability and reproducibility were evaluated by measuring them with an auto-lensmeter by two examiners. Results: Measured powers by dry blotting method were ranged in mean differences from 0.03D to 0.18D for overall lenses, 0.10D to 0.18D for silicone hydrogel lenses, 0.03D to 0.08D for hydrogel lenses. The mean differences between two examiners were less than 0.10D, and the inter-examiner reproducibility was good for dry blotting method. The mean difference between powers determined by wet cell method were 0.09D to 0.69D, the mean differences between two examiners were 0.02D to 0.59D. The reliability of measurements and inter-examiner reproducibility were less than dry blotting method. Conclusions: The reliability of measurements for all materials was better in dry blotting than wet cell method, the re liability of measurements for silicone hydrogel lenses was low in both methods. In clinical practical which requires quick checking of back vertex power using an auto-lensmeter. dry blotting method is thought to be more efficient than wet cell one.

• Journal of Korean Clinical Health Science
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• v.4 no.4
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• pp.762-768
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• 2016

Purpose. This study was performed on survey related optician's perception of NCS and required jobs to develop curriculum of department of ophthalmic optics Methods. This study was to evaluate the questionnaire survey of 63 opticians working in Optometrist in Daegu Metropolitan City from November 1, 2016 to November 18, 2016. Results. As for the opticians who know about NCS, 23.8% of the respondents answered that the opticians' perception of NCS is very low. For the four required jobs of the technical part, less than 5 years of optometrists ; optometry 73.7% > fitting 47.4% > ophthalmic dispensing 36.8% > lensmeter 5.3%, more than 5 years and less than 10 years of optometrists ; optometry 84.6% > fitting 53.8% > lensmeter 46.2% > ophthalmic dispensing 38.5%, more than 10 years of optometrists ; optometry 67.7% > ophthalmic dispensing 51.4% > lensmeter 19.4% > fitting 16.1%. For the four required jobs of the management, less than 5 years of optometrists ; product 57.9% > service 47.4% > manners 10.6% > sales 5.3%, more than 5 years and less than 10 years of optometrists ; service 76.9% > product 53.9% > manners 46.2% > sales 38.5%, more than 10 years of optometrists ; service 45.2% > manners 42.0% > product 32.3% > sales 19.4%. Conclusions. Although there were 108 required jobs of the technical part and 94 required jobs of the management part, the technical level of the department of ophthalmic optics was satisfactory, but the classes of the management part were insufficient. It will be necessary to actively reflect the needs of industry through curriculums reform.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.4
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• pp.455-462
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• 2015

Purpose: To develop more accurate wet measuring system combining the wet cell, automatic lensmeter and the related software for hydrophilic contact lenses and to verify the accuracy of those measuring holder system already available in the market. Methods: Refractive power measurement were done in both a conventional method which has been commonly used in optical shops and a new method which is recently developed in korea. Hydrophilic contact lens of korean brand was chosen as a test material and was tested by water content ratio and by spherical refractive power. Results: When spherical power of -3.00 D contact lens is measured in the newly developed wet cell measurement holder with automatic lensmeter, it reads -3.01 D at water content ratio of 38%. -3.00 D at 45% and -2.98 D at 58%. The same experiment with the Poster soft contact lens wet cell measurement holder maintaining other conditions same resulted in -3.60 D at the water content ratio of 38%, -3.06 D at 45% and -2.46 D at 58%. Conclusions: At the higher water content, the refractive power values measured by both of the wet cell measuring holders are shown lower, and additionally, the new method using the wet cell holder and new software program in a automatic lensmeter showed more accurate readings than conventional Poster soft contact lens wet cell measuring system.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.2
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• pp.105-115
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• 2015

Purpose: The accuracy for measuring the refractive power of hydrogel contact lenses by spectacle lens holder and contact lens holder was evaluated. The accuracy for each sample was also analyzed with water content and diopter categories. Methods: The hydrogel contact lenses used for measurement were classified into three categories in water content (38%, 43%, 58%). Also, three diopter categories of refractive power were used such as -3.000 D, -7.000 D, -10.000 D. And also, the reliability of measurement results were evaluated by measuring refractive power with spectacle lens holder and contact lens holder using an Manual lensmeter. Results: In case of spectacle lens holder method, the average value of refractive power was -3.3273D for -3.0000 D, -7.1306 D for -7.0000 D and -10.2944 D for -10.0000 D, respectively. In case of contact lens holder method, the average value of refractive power was -3.1060 D for -3.0000 D, -7.0028 D for -7.0000 D and -10.2611 D for -10.0000 D, respectively. In measurement of all diopters, the accuracy of contact lens holder method was better than spectacle lens holder method. Conclusions: From these results, it is judged that the refractive power of soft contact lens by manual lensmeter with contact lens holder have a higher accuracy than spectacle lens holder.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.4
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• pp.405-410
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• 2005

In this paper, the front radiuses of curvature of spherical spectacle lenses in the cosmetic and optical point of view are investigated and are calculated using Zinken-Sommer condition. The optical power of all spherical spectacle lens shows good quality at the test using autometic lensmeter. However the front radiuses of curvature of spherical spectacle lenses are quite different depending on the lens companies. The front radius of curvature of those lenses is larger than that calculated using Zinken-Sommer condition. We know that the front radius of curvature of commercial spectacle lens is emphasized more cosmetic aspect than optical point of view.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.2
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• pp.417-421
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• 2004

We can see that two images of reflection are observed on the surface of a ophthalmic lens. These are the image reflected from front surface and back surface of lens, respectively. The reflective image shows to be affect by surface refractive power of front and back surface of lens. Total refractive power of lens is calculated by refractive power of front and back surface of lens. Accordingly, the ratio of image on the lens surface is able to measure refractive power of ophthalmic lens without helping of the lensmeter. The ratio of two reflective image measured on the lens surface is compared with the calculated ratio by the power measurement.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.4
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• pp.501-509
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• 2015

Purpose: To evaluate the reliability of refractive power by comparing the marked refractive power in an automatic phoropter and actually measured spherical/cylindrical refractive power. Methods: Actual refractive power of minus spherical lens and cylindrical lens in an automatic phoropter was measured by a manual lensmeter and compared with the accuracy of marked refractive power. Furthermore, combined refractive power and spherical equivalent refractive power of two overlapped lenses were compared and evaluated with the refractive power of trial lens. Results: An error of 0.125 D and more against the marked degree was observed in 70.6% of spherical refractive power of spherical lens which is built in phoropter, and the higher error was shown with increasing refractive power. Single cylindrical refractive power of cylindrical lens is almost equivalent to the marked degree. Combined spherical refractive power was equivalent to spherical refractive power of single lens when spherical lens and cylindrical lens were overlapped in a phoropter. Thus, there was no change in spherical refractive power by lens overlapping. However, there was a great difference, which suggest the effect induced by overlapping between cylindrical refractive power and the marked degree when spherical lens and cylindrical lens were overlapped. Spherical equivalent refractive power measured by using a phoropter was lower than that estimated by trial glasses frame and marked degree. The difference was bigger with higher refractive power. Conclusions: When assessment of visual acuity is made by using an automatic phoropter for high myopes or myopic astigmatism, some difference against the marked degree may be produced and they may be overcorrected which suggests that improvement is required.