• Journal of Korean Ophthalmic Optics Society
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• v.11 no.1
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• pp.63-69
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• 2006

Clinical evaluation by Astigmatic Components of autorefractors was performed to examine validity and accuracy compared with subjective refraction. The mean cylindrical powers of Astigmatic Components of Subjective Refraction, Closed-view and Open-view were found to be $-0.689{\pm}0.516D$, $-0.691{\pm}0.530D$, $-0.470{\pm}0.507D$, respectively. The Difference of cylindrical Components between Subjective Refraction and Closed, Open-view were found to be $0.002{\pm}0.191D$, $0.015{\pm}0.137D$, respectively. Approximately 85% of Closed-view and Open-view autorefractor measurements were within ${\pm}20^{\circ}$ range of the difference of cylindrical axis with subjective refraction. The mean $J_0$ Components of Astigmatic Components of subjective refraction, Closed-view and Open-view were found to be $-0.155{\pm}0.332D$, $-0.004{\pm}0.178D$, $-0.001{\pm}0.156D$, respectively. The mean $J_{45}$ Components of Astigmatic Components, Closed-view and Open-view were found to be $-0.023{\pm}0.227D$, $-0.026{\pm}0.172D$, $-0.014{\pm}0.182D$, respectively. Both of the Closed-view and Open-view refractor showed available accuracy in measuring astigmatic components.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.8
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• pp.3933-3940
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• 2013

The purpose of present study was to determine the frequency of RA with age and to investigate the age-related trends and changing-factors in RA, CA and IAs. The refractive power of the eye and the power of corneal anterior surface were measured with auto-refractor among 1,017 inhabitants aged 5 to 59 years in Cheongju in July 2010. The overall frequency of RA was 22.7%, and frequency of RA increased from 8.9% in 5~9 years age group to 36.8% in 20~29 years age group. It then dipped to 19.2% in 40~49 years age group but increased again 28.6% in 50~59 years age group. $J_{45}$ components for RA, CA, and IAs were fairly stable in different age groups, the changes in $J_0$ components for both RA and CA appeared to be decreased after age of 30 years. In addition, the refractive power on the vertical direction was changed slightly with age, but the refractive power on the horizontal direction was changed significantly with age. It was expected that the change in the frequency of astigmatism with age was due to the change in the refractive power of horizontal meridian.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.2
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• pp.47-59
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• 2007

When the fixation point moved far distance to near distance, the change of astigmatism type in total astigmatism showed no-changed eyes: 1,020 eyes (63.8%), changed eyes: 578 eyes(36.1 %). The change of with-the-rule into oblique-astigmatism, oblique-astigmatism into with-the-rule, against-the-rule into oblique-astigmatism of change was plenty the most respectively. In corneal astigmatism was no-changed eyes: 1,164 eyes (72.8%), changed eyes: 434 eyes(27.1%). The change of with-the-rule into oblique-astigmatism, oblique-astigmatism into with-the-rule, against-the-rule into with-the-rule astigmatism was plenty the most respectively. In residual astigmatism is no-changed eyes: 935 eyes(58.5%), changed eyes: 663 eyes(41.4%). The change of with-the-rule into oblique-astigmatism, oblique-astigmatism into against-the-rule, against-the-rule into oblique-astigmatism was plenty the most respectively. When the fixation point moved far distance to near distance, the change of astigmatism axis in total astigmatism was no-changed eyes: 761 eyes(48.5%), cyclotorsioned eyes the above 10 degrees: 837 eyes(52.3%). In corneal astigmatism was no-changed eyes: 846 eyes(52.9%), cyclotorsioned eyes the above 10 degrees : 752 eyes(47%). In residual astigmatism was no-changed eyes: 614 eyes(38.4%), cyclotorsioned eyes the above 10 degrees : 984 eyes(62.5%). The magnitude of cyclotorsion of astigmatism axis in total astigmatism was Counter clockwise rotation: 31 degrees, clockwise rotation: 20 degrees. In coneal astigmatism was Counter clockwise rotation: 25 degrees, clockwise rotation: 27 degrees. In residual astigmatism was Counter clockwise rotation: 33 degrees, clockwise rotation: 35 degrees.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.2
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• pp.25-36
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• 2007

We researched the change of astigmatism power when the fixation point moved from far distance to near distance. Astigmatism power was measured by using both eyes open-view auto-refractometer. We divided the ages between 5 and 67 years old into 12 groups with 1,598 healthy eyes(male-698 eyes and female-900 eyes) without eyes problems and experiences of eyes operations. The mean power in far astigmatism showed that with-the-rule of the total astigmatism: -0.79D, with-the-rule of the corneal astigmatism: -1.07D and against-the-rule of the residual astigmatism : -0.79D were found most respectively. The correlation between cornea astigmatism and total astigmatism was y=0.7493 x + 0.5661 r=0.6510, residual astigmatism and total astigmatism was y=0.248 x - 0.5926 r=0.2598 and corneal astigmatism and residual astigmatism was y=-0.4439 x - 0.1813 r=-0.5551 in the far distance. The mean power in near astigmatism showed that with-the-rule of total astigmatism : -0.92D, with-the-rule of corneal astigmatism : -1.12D, against-the-rule of residual astigmatism : -0.87D were found most respectively. In the near distance, The correlation between corneal astigmatism and total astigmatism was y=0.6872 x + 0.5934 r=0.6204, residual astigmatism and total astigmatism was y=0.303 x - 0.6066 r=0.3165, corneal astigmatism and residual astigmatism was y=-0.46 x - 0.0626 r=-0.5322. When the fixation point moved far distance to near distance, the differences of power according to the type of astigmatism were total astigmatism: $-0.07D{\pm}0.44D$, corneal astigmatism: $-0.04D{\pm}0.54D$ residual astigmatism:$0.01D{\pm}0.53D$. Most of astigmatism refractive power was increased except for oblique-the -astigmatism. When the fixation point moved far distance to near distance, the change of astigmatism refractive power showed total astigmatism: 540 eyes(33.7%), corneal astigmatism: 638 eyes(39.9%), residual: 841 eyes(52.6%).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.9
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• pp.5621-5627
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• 2014

To specify the standard of LASEK surgery, this study examined the determination factors affecting the high order aberrations (HOAs) in preoperative and postoperative LASEK. 51 adult patients (102 eyes) were evaluated at the baseline and 2 months after LASEK surgery from Nov 2011 to Jul 2012. The postoperative HOAs ($0.538{\mu}m$) were higher than the preoperative ($0.341{\mu}m$). In linear regression analysis, the refractive components that affected the postoperative HOAs were $J_0$ of corneal astigmatism (CA, 0.400), $J_0$ of refractive astigmatism (RA, 0.389), corneal astigmatism (CA, 0.282), spherical equivalent (SE, 0.239), refractive astigmatism (RA, 0.213), and pupil size (PS, 0.194) with a high R. In multiple regression, $J_0$ of CA, PS and SE were significant factors with the postoperative HOAs. In conclusion, both HOAs and $J_0$ of CA should be considered when determining the suitable factors for LASEK surgery.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.6 no.1
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• pp.38-44
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• 1981

This paper is for the design and construction of TV translator using in the areas where TV signal is not detectible. In this paper, theoretical design method and the scheme to decrease the intermodulation occurred by the harmonics of local oscillator are proposed. In the processes of design we have known that intermodulation of wideband IF amplifier is cannot avoidable when only single IF band is used for all the TV channels As the input vs output characteristics of TV trasnlator we have obtained the constant output signal level of +30 dBm for the input signal levels of -76dBm~-26dBm. And in the 6MHz passband, more than 95% of linearity is obtained.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.4
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• pp.55-69
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• 2007

The purpose of this study was to perform a clinical test using ez NANOsence II RGP contact lenses for the effects of visual acuity and cornea on subjects with abnormal refraction status. One hundred twenty one adults (twenty nine males, ninety two females, range = 17 to 43, mean = 22.86) were recorded. The subject's history including, the symptoms from previous lens wear, were studied. The subjects were observed, both pre and post lens wear, for any symptoms and signs of change of the eye. The Visual acuity and the binocular status were tested at the far distance using the contact lens. The refraction test was performed on the naked eye using the objective method (Topcon KR-8100, Japan). The Stereopsis test was performed at the near distance after contact lens wear by the Titmus fly (Stereo Optical Co., U.S.A) and TNO (TECH, The netherlands). The contrast sensitivity diagnosis was performed at 1m distance after contact lens wear by the contrast sensitivity chart (pelli-Robertson, USA). The corneal topography was analyzed on the naked eye after lens wear by ORB scan (Bausch Lomb, U.S.A.). The ultra structure of surface on the contact lens was observed using SEM (JMS-5800, Japan). The chemical component's of the contact lens was analyzed by EDS program. The results of this study were as follows: 1. The longer of contact lens wear period, The subjects have acquired the most improved visual function. 2. Subjects had experienced few side effects wearing the contact lenses. 3. The lenses were easy to use by the subjects. 4. The longer of contact lens wear period, the power of cornea had more decrease. but the base curve of cornea had more increase and corneal astigmatism was decrease (p<0.01). Also, the thickness of corneal center was few decrease. 5. Longer periods of using the contact lens showed stereopsis and contrast sensitivity at more normal values. 6 The corneal topographical after lens wear showed most subjects with similar morphology for different wear periods. 7. The surface ultrastructure of the new and used contact lens was the similar fine shape. 8. The chemical component's of in the new and used contact appeared to have similar results. In conclusion, this study showed that the surface ultrastructure and chemical component's of the new and used contact lens are similar. In addition, the subjects had improved the quality of vision and few experienced any side effects during long periods of contact lens wear. Also they have decrease of corneal astigmatism during the long period of lens wear. Our test has showed that the chemical composition and fine structure of contact lens have related to the visual function on contact lens wearer. In this paper, we suggested that ez NANOsence II RGP contact lenses had a moderate effect for correcting vision of abnormal refraction eye.