• Journal of the Optical Society of Korea
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• v.15 no.1
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• pp.68-73
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• 2011

This study investigated, using the Orbscan II topography system, the influence of age and sex related changes on the corneal thickness and anterior corneal curvature, more specifically the fine structure of the cornea, in a Korean young population. The Orbscan II topography system is a computer-assisted slit-beam scanning technology that can map the anterior section of the cornea. The mean central corneal thickness of all subjects was $547.532{\pm}44.529\;{\mu}m$. There was no statistical difference (p>0.5) in the mean central corneal thickness between males and females. Sex and age related changes in the mean central corneal thickness had no specific statistical difference (P>0.5). There was a negative correlation between the anterior corneal curvature and the central corneal thickness in all subjects, except for the twenty year olds. However, the thickness relationship between the mean central corneal and the eight paracentral corneal thicknesses had strong statistical differences in all subjects. Also age and sex related changes in the central corneal thickness and the anterior corneal curvature in all subjects had no statistically significant difference, except from 20-26 years old (p>0.05). This information could be a suitable reference basis for future studies in the young population of Asia and for the development of examination tools for corneal refractive surgery.

• Journal of Korean Clinical Health Science
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• v.4 no.3
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• pp.652-661
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• 2016

The analysis of cornea morphology using corneal topographers is a clinical practice for the diagnosis of keratoconus in contact lens fitting. The recently technique has developed with the possibility of achieving a great number of measuring points of both anterior and posterior corneal surfaces in cornea. Also these data are used to extract a series of topographic valuation indices that permit to offer the most exact clinical diagnosis of keratoconus in contact lens fitting. This study describes the technologies in which current corneal topographers are based on the morphological characteristics that the keratoconus status observe on corneal surface. Therefore, this paper can provide that the analysis of corneal topographers applied for the diagnosis of keratoconus in contact lens fitting.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.2
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• pp.223-232
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• 2012

Purpose: Validating a new research method to determine posterior corneal curvature and asphericity(Q) in vivo, based on measurements of anterior corneal topography and corneal thickness. Methods: Anterior corneal topographic data, derived from the Medmont E300 corneal topographer, and total corneal thickness data measured along the horizontal corneal meridian using the Holden-Payor optical pachometer, were used to calculate the anterior and posterior corneal apical radii of curvature and Q. To calculate accurate total corneal thickness the local radius of anterior corneal curvature, and an exact solution for the relationship between real and apparent thickness were taken into consideration. This method differs from previous approach. An elliptical curve for anterior and posterior cornea were calculated by using best fit algorism of the anterior corneal topographic data and derived coordinates of the posterior cornea respectively. For validation of the calculations of the posterior corneal topography, ten polymethyl methacrylate (PMMA) lenses and right eyes of five adult subjects were examined. Results: The mean absolute accuracy (${\pm}$standard deviation(SD)) of calculated posterior apical radius and Q of ten PMMA lenses was $0.053{\pm}0.044mm$ (95% confidence interval (CI) -0.033 to 0.139), and $0.10{\pm}0.10$ (95% CI -0.10 to 0.31) respectively. The mean absolute repeatability coefficient (${\pm}SD$) of the calculated posterior apical radius and Q of five human eyes was $0.07{\pm}0.06mm$ (95% CI -0.05 to 0.19) and $0.09{\pm}0.07$ (95% CI -0.05 to 0.23), respectively. Conclusions: The result shows that acceptable accuracy in calculations of posterior apical radius and Q was achieved. This new method shows promise for application to the living human cornea.

• Journal of Korean Clinical Health Science
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• v.1 no.2
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• pp.31-37
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• 2013

Purpose. This study was to investigate the analysis of the central corneal thickness and anterior chamber depth of eyes in Korean Young Population using the Pentacam topography. Methods. The subjects consisted of 126 eyes from normal cornea of Korean aged 7-12($8.857{\pm}1.501$) years during 2009. The thinnest location, pachy apex, and pupil central region of the cornea thickness was measured using the Pentacam pachymetry. The anterior chamber depth of normal corneas was measured with Pentacam. Results. The thinnest location of corneal thickness was $547.413{\pm}37.893$um. The pachy apex of cornea thickness was $552.103{\pm}36.016$um. Also, the pupil center of corneal thickness was measured $552.143{\pm}36.418$um. On the other hand, the mean thickness in the central cornea was a statically significant relationship(t-test, p=0.0002) between pachy apex and thinnest zone. Also the mean thickness of the central cornea was a statically significant correlation(pearson p=0.0001) among the pupil center, pachy apex and thinnest zone. The anterior chamber depth was $3.137{\pm}0.308$mm. The mean depth in the anterior chamber of cornea was a statically relationship(t-test, p>0.05) between OD and OS. Conclusions. The results of this clinical study suggested that the analysis of the central corneal thickness and anterior chamber depth using Pentacam in Korean young population can provide the useful morphological information in diagnosis of cornea for the contact lens fitting and corneal refraction surgery.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.2
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• pp.109-114
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• 2006

We evaluated the contour using corneal asphericity of the myopic cornea in Korea and investigated the relationship between refractive error and other ocular dimensions in Korean myopia, including anterior chamber depth and asphericity. The monoocular asphericity value of 50 myopes with $-4.83{\pm}2.38$ D between early 20 age and early 30 age in adult was included. Cycloplegic refraction, corneal asphericity and anterior chamber depth using corneal topography were examined. The mean asphericity values were$-0.27{\pm}0.13$ and the corneas of 96.0% were prolate ellipse. Refractive error was related to asphericity and anterior chamber depth among myopes. However, asphericity only were significant difference in high and low myopia group. Corneal configuration on the contact lens fits are discussed. We think that the longitudinal study for myopia and asphericity was required.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.1
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• pp.111-120
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• 2014

Purpose: This study was to investigate changes in the thickness of cornea, curvature of cornea, and aberration depending on the water contents, materials, and refractive power of contact lens. Methods: The differences in the corneal thickness between pre- and post-wearing the lenses were compared using 5 kinds of lenses. The changes in the corneal thickness, the curvatures of the anterior and posterior cornea, and high order aberration (HOA) before and after wearing the lenses were investigated at the center of the cornea, and the different distance and the direction away from the center of the cornea. For the equipments of measurement, ORB ScanII (Bausch & Lomb Inc, ver 3.14) was used to measure the corneal topography and thickness, and Zywave (Bausch & Lomb Inc, ver 5.20) was used to analyze the high order aberration. Results: Five (S1, S2, S3, T1, T2) of the lens was used for this study, excluding the lens T2 lens has four lenses and the thickness of the corneal shape, but the impact is minimal. In the case of the hydrogel soft contact lenses (T2 lens) with low oxygen permeability, the corneal thickness showed distinct increasing patterns. The high order aberration and coma aberration were most changed in the silicon hydrogel toric lens, while the depth of anterior was most changed in the hydrogel toric lens. Conclusion: Among the 5 kinds of contact lenses with different water contents, materials, and refractive power used for this study, the corneal shape change was small for the lenses with an oxygen permeability (Dk) of more than 28, and the largest for the lenses with a very low oxygen permeability.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.2
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• pp.61-66
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• 2007

This study was to analysis the values for anterior and posterior Best-Fit Sphere(BFS) in a Korean emmetropic population using the Orbscan II system. Cycloplegic refraction and anterior and posterior BFS were performed 40 eyes of 20 patients and we compared the results by sex and between the two eyes. Respectively, the 1, 3, 5mm zone average of anterior BFS showed each $5.63{\pm}3.49{\mu}m$, $4.48{\pm}2.81{\mu}m$ and $2.14{\pm}1.82{\mu}m$. The 1, 3, 5mm zone average of posterior BFS showed each $22.54{\pm}10.25{\mu}m$, $15.88{\pm}7.55{\mu}m$ and $4.43{\pm}4.94{\mu}m$ in 40 emmetropic eyes. Anterior and posterior BFS were not statistically significant difference in male and female using Mann-Witney U test.