• Journal of Korean Ophthalmic Optics Society
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• v.6 no.2
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• pp.53-57
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• 2001

The corneal structure and function changes somewhat with aging. We were performed the analysis of women college students on the base curve, power, and astigmatism axis of the cornea by keratometer. All women subjects were between the ages of 19 and 20 years. On the corneal base curve. the right eye of the ages of 19 was 7.64 mm in vertical and 7.81 mm in horizontal. But, the left eye was 7.65 mm in vertical and 7.83 mm in horizontal on the other hand, the right and left eye of the ages of 20 was 7.72 mm in vertical and 7.75 mm in horizontal. On the corneal diopter power, the right eye of the ages of 19 was 44.21 diopter in vertical and 43.32 diopter in horizontal. But, the left eye was 44.23 diopter in vertical and 43.24 diopter in horizontal. On the other hand, the right eye of the ages of 20 was 43.67 diopter in vertical and 43.62 diopter in horizontal. But, the left eye was 43.73 diopter in vertical and 43.6 diopter in horizontal. According to the corneal astigmatism axis style, the right eye of the ages of 19 have 83% positive for with the rule astigmatism, and 16% positive for against the rule astigmatism. But, the left eye of the ages of 19 have 86% positive for with the rule astigmatism, and 12% positive for against the rule astigmatism. On the other hand, the right eye of the ages of 19 have 56% positive for with the rule astigmatism, and 44 % positive for against the rule astigmatism. But, the left eye of the ages of 20 have 56% positive for with the rule astigmatism, and 41% positive for against the rule astigmatism. According to the diopter power of corneal astigmatism. The right eye of the ages of 19 have 36% positive for behind 1 diopter and left eye have 31%. But, the right and left eye of the ages of 20 have 37.5%. The right and left eye of the ages of 19 have 42% positive for 1 diopter, and the right eye of the ages of 20 have 34.4% positive for 1 diopter and the left eye have 43.8%. The right eye of the ages of 19 have 12% positive for 2 diopter and left eye have 22%. But, the right eye of the ages of 20 have 15.6% positive for 2 diopter and the left eye have 12%. The right eye of the ages of 19 have 4% positive for 3 diopter and left eye have 3%. But, the left eye of the ages of 20 have 3% positive for 3 diopter and the left eye have 6%. On the other hand, the right eye of ages of 19 have 6% positive over 4 diopter, and the left eye have 2%. But, the right eye of ages of 20 have only 9% positive over 4 diopter.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.3
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• pp.201-206
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• 2010

Purpose: This study was to know the correlation among the dimensions of ocular components and refractive error on kindergarten children. Methods: The subjects were 80 preschool students who had no eye diseases. The refraction, corneal diopter, corneal radius, inter-pupillary distance, axial length, anterior chamber depth and dominant eye were measured and analysed. Results: It was shown that the highest correlation was between the axial length and the corneal diopter (r=-0.674, p=0.000). The ratio of height, weight and axial length (AL) to Corneal radius (CR) ratio were positively correlated with the axial length (r=0.351, r=0.408, r=0.488). The spherical equivalent of the refractive error and the corneal diopter were negatively correlated with the axial length (r=-0.302, r=-0.674). The anterior chamber depth and the corneal diopter were positively correlated with the AL/CR ratio (r=0.422, r=0.280). The spherical equivalent of the refractive error and the corneal radius were negatively correlated with the AL/CR ratio. Conclusions: It was shown that the AL/CR ratio was a very important indicator for diagnosing the refractive error of the preschoolers.

• Journal of Korean Ophthalmic Optics Society
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• v.1 no.2
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• pp.71-76
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• 1996

As the results of measurement of the radius of corneal curvature with keratometer, for the right eye of 91 male adults, horizontal radius is 7.16 mm to 8.49 mm and vertical radius is 7.03 mm to 8.34 mm, and for the left eye of male adults, horizontal radius is 7.10 mm to 8.48 mm and vertical radius is 7.01 mm to 8.24 mm. In case of 61 female adults, horizontal radius is 7.16 mm to 8.45 mm, vertical radius 7.11 mm to 8.18 mm for the right eye, and horizontal radius 7.15 mm 108.43 mm and vertical radius 7.01 mm to 8.26 mm for the left eye. The mean value of radius of corneal curvature is 7.74 mm for male and 7.69 mm for female. Also the mean value of horizontal radius is 7.79 mm and vertical radius is 7.64 mm. Overall mean value of the radius of corneal curvature is 7.71 mm that is corresponded to Gullstrand's eye. The horizontal radius is 0.15 mm bigger than vertical radius.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.2
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• pp.123-133
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• 2011

Purpose: The present study was conducted to analyze any difference in the movement of aspheric RGP lens by the amounts of keratometiric astigmatisms using keratometer and corneal topography. Methods: Corneal curvatures in thirty six eyes of males and females of with-the-rule keratometric astigmatisms in their twenties were measured by a keratometer and worn aspheric RGP lenses. Then, lens rotations, vertical and horizontal movements of lens by blinking were measured to compare with lens movements when aspheric RGP lenses were fitted by total keratometric astigmatisms using corneal topography. Results: The case having higher amount of central keratometric astigmatism was 61.1% of subjects, however, 36.1% of subjects showed higher total keratometric astigmatism indicating that central keratometric astigmatism was not always bigger than total keratometric astigmatism. Since over 0.25 diopter difference between total and central keratometric astigmatisms was shown in 19 eyes (52.8% of subjects), the prescription for lens fitting could be changed. Significant difference in horizontal movement was detected with increase of astigmatism when it compared based on the amount of keratometric astigmatism measured by a keratometer. However, there was no significant difference in lens rotation, horizontal and vertical movements by comparison with the amount of total keratometric astigmatism using a corneal topography. When central keratometric astigmatism measured by keratometer was bigger than total keratometric astigmatism estimated by corneal topography, bigger lens rotation was shown compared with opposite case. Also, the tendency of bigger lens rotation was measured with the increase of keratomatric astigmatism in the case of same prescription having same base curves with same amount of keratometric astigmatism but different curvatures. Conclusions: From the present study, we concluded that lens movements on cornea were not totally different when aspheric RGP lens fitted on with-the-rule astigmatism by keratometer and corneal topography. However, there was some difference in certain lens movements. Therefore, we concluded that further study on the relationship between the prescriptions for lens fitting should be conducted for improving the rate of successful lens fitting by keratometer or for the proper application of corneal topography for lens fitting.

• Journal of Digital Convergence
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• v.11 no.1
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• pp.315-320
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• 2013

We have investigated the variation of spherical aberration of the anterior and posterior surface in a Korean sample population with various age between 20 to 71 years old. We used Pentacam (Oculus Inc., Germany) to measure the corneal radius, asphericity, and spherical aberration of 290 patients with normal cornea. There were negative correlation between corneal anterior radius and spherical aberration(r = -0.22, p<0.0001), and, there were negative correlation between corneal posterior radius and spherical aberration(r=-0.27, p < 0.0001). There were positive correlation between anterior asphericity and spherical aberration(r = 0.24, p < 0.0001), however there were negative correlation between posterior asphericity and spherical aberration(r = -0.17, p=0.00288).The average of anterior spherical aberration and posterior spherical aberration was $0.482{\pm}0.099{\mu}m$ and $-0.098{\pm}0.029{\mu}m$. The average of spherical aberration was $0.385{\pm}0.097{\mu}m$. There were significant positive correlations between anterior spherical aberration and age(r = 0.227, p<0.0001), and there were positive correlations between posterior aberration and age(r = 0.349, p<0.0001). It is considered that this data can be used as basic information for furture studies for improving the quality of vision of modern human and, through the analysis of the spherical aberration of cornea was to provide a better understanding of the optical part of the Korean's eye.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.1
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• pp.41-50
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• 2011

Purpose: The present study was conducted to compare the centration of RGP lens on cornea when lens was fitted based on keratometric astigmatisms measured by keratometer and the lens centration when fitted by corneal topography. Methods: Thirty eight eyes of 19 male and female in their twenties were applied RGP lens with 9.9 mm of diameter by the keratometric astigmatisms classified by the measurement with a keratometer. Then, lens centrations were estimated using high speed camera and compared with the lens centration when fitted by total keratometric astigmatism using corneal topography. The relationship of the steepest location of cornea and lens centration was further compared. Results: With the rule astigmatism, lens centration was not changed even with the difference in central and total keratometric astigmatisms. When the relationship of the steepest part of cornea measured by corneal topography and lens centration was analyzed, the lens centration in vertical direction was exactly correlated with the steepest part of cornea in 52.3% of subjects. In the case of non-correlation, the steepest part of cornea was mostly upper part of cornea, however, lens centration was located on lower part of cornea. The lens centration in horizontal direction was exactly correlated with the steepest region of cornea in 65.6% of subjects. In non-correlated case, the difference in cornea curvatures between the steepest and the flattest parts was smaller than 0.05 mm in 76.9% of subjects. Conclusions: From these results, we conclude that corneal topographic patterns may more contribute the centration of RGP lens on cornea than the difference in central and total keratometric astigmatisms.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.3
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• pp.279-289
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• 2013

Purpose: To evaluate the changes of refractive power when worn soft contact lenses were temporarily removed. Methods: 91 soft contact lens wearers (15 males and 76 females; total 182 eyes) from 17 to 39 years of age (average: $24{\pm}4.8$ years) were participated. Objective and subjective refraction, and corneal radius were measured at 0, 30, 60 and 90 min after lens removal. The changes in refractive power were evaluated between measurements over time. The other parameters such as types of lenses, fitting and wearing conditions were also assessed. Results: Objective refraction, subjective refraction and corneal radius were significantly changed according to measured time (p<0.0001). A moderate myopic shifts was observed at the beginning (30 min after lens removal) and a slight myopic shift at the late of measurement (60 min to 90 min after lens removal). There are no significant differences between lens types, fitting states, wearing time, wearing days and sleeping time in the previous day. However, there was significant interaction in changes for corneal radius between measuring time and lens type (p=0.017), fitting state (p=0.019), and sleeping time prior to the test (p=0.010). Conclusions: Time to reach refractive and corneal radius stability after contact lens removal revealed at least more than 60 min, regardless of types of lenses, fitting and wearing conditions. Therefore, refraction for correction should be performed after waiting for more than that time as possible.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.3
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• pp.7-15
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• 2009

Purpose: To investigate the corneal recovery after discontinuing orthokeratology (OK) lenses wear in children for long-term period. Methods: Among the OK lens wearers who wear over 8 months and showed successful refractive correction, 25 subjects were selected who want to discontinue the OK lenses. Uncorrected visual acuity, refractive correction, corneal curvature (Sim K), central corneal thickness and corneal eccentricity were measured during the OK lens wearing period and after discontinuation for 1 month. Results: Uncorrected visual acuity and corneal shape had remodeled significantly during the OK lens wear and recovered significantly during the first week of discontinuation. Uncorrected visual acuity and refractive correction had achieved full recovery 2 weeks after discontinuation of lens wear and were highly correlated with the changes in corneal thickness. But corneal shape recovered slowly, eccentricity had recovered fully after 1 month and corneal curvature and central thickness had not been achieved full recovery until 1 month after discontinuation. Conclusions: Recovery of after longterm use of OK lens is rapid for refractive change, but slow for corneal curvature and central thickness that to refit the contact lenses, practitioners need patience.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.3
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• pp.299-303
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• 2012

Purpose: In this study the correlation among the myopic refractive error and ocular components in primary school students was investigated. Methods: The subjects were 62 children who had no eye diseases. The refractive error, corneal radius, anterior chamber depth, lens thickness, axial length were measured and analysed. Results: Myopic refractive error in primary school students was negatively correlated with the axial length (1~3rd grade r=-0.653, p=0.000/4~6th grade r=-0.742, p=0.000), AL/CR ratio (1~3rd grade r=-0.571, p=0.000/4~6th grade r=-0.852, p=0.000). Conclusions: It was shown that the axial length and axial length(AL)/corneal radius(CR) ratio were very important data for myopic refractive error in primary school students.

• Journal of Digital Convergence
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• v.10 no.11
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• pp.535-540
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• 2012

This study is to research the differences of tear film for young people in of a day in a restricted indoor space. The subjects are 58 eyes volunteers for twice preliminary inspection and tear test of a day. 58 healthy individuals with no eye disease, no body disease, orthophoria, corrective visual acuity more than 0.8, binocular spherical equivalence difference over 0.50 diopter, the flattest corneal curvature in horizontal meridian and the steepest corneal curvature in vertical meridian were tested. The uncorrective visual acuity, refractive error, corneal curvature, schirmer test and tear break up test were performed in the morning and afternoon. Schirmer test were $16.0{\pm}7.0mm$ in the morning and $14.1{\pm}7.1mm$ in the afternoon. TBUT were $11.3{\pm}0.6$ sec in the morning and $12.1{\pm}0.9$ sec in the afternoon. They have no significant differences.