• Journal of Korean Clinical Health Science
• /
• v.9 no.1
• /
• pp.1478-1485
• /
• 2021

Purpose. To analysis of astigmatism in Korean adults from 20 to 29 years old. Methods. From January 2019 to February 2020, one hundred two subjects were performed in refraction test using the Auto-Refractometry. Results. In the type of astigmatism based on refractive error, the male's right eye was 4.26% simple myopic astigmatism and 95.74% complex myopic astigmatism, and the left eye was 2.22% simple myopic astigmatism and 97.78% complex myopic astigmatism. However, in the female's right eye, simple myopic astigmatism was 2.27%, complex myopic astigmatism was 97.73%, and left eye was simple myopic astigmatism was 2.17%, complex myopic astigmatism was 97.83%. The types of astigmatism in men and women similar to other. The mean refractive astigmatism values were -0.922±-0.798 diopter and -0.877±-0.707 diopter for male right and left eye, and -0.765±-0.599 diopter and -0.853±-0.586 diopter for female. On the other hand, the refraction values of the right and left eyes of men and women have statistical significance(p=0.000). The mean power comparative between refractive astigmatism and corneal astigmatism power were -0.186±-0.745 diopter, -1.091±-0.589 diopter in male and -1.140±-0.593 diopter, -1.140±-0.534 diopter in female. Therefore, the mean power values of the refractive astigmatism and corneal astigmatism of men and women were statistical significance(p=0.000). At the 0.75 diopter or more, which can have clinical symptoms of astigmatism power, males have 60.86% and 72.09% of the right and left eyes, and females have 47,64% and 60.10% of the right and left eyes. At 0.75 diopter or more, which can have clinical symptoms of corneal astigmatism power, males have 68.75% and 74% of the right and left eyes, and females have 86.50% and 82.35% of the right and left eyes. In the type of astigmatism axis, both men and women had a high frequency of the rule astigmatism. However, men had a high frequency of against-the-rule astigmatism and women showed a high frequency of oblique astigmatism. Conclusions. In this study, the complex myopic astigmatism and with-the rule astigmatism was the most common of all subjects. However, there was a statistical significance between right and left eyes of all subjects. The corneal astigmatism was higher refractive values in both males and females than refractive astigmatism. This study suggests that the analysis of the astigmatism can provide the useful diagnosis information for the correction of visual acuity.

• Journal of Korean Ophthalmic Optics Society
• /
• v.21 no.2
• /
• pp.91-98
• /
• 2016

Purpose: This study investigated the masking effect of the hydrogel lens and silicone hydrogel lens on the cornea with refractive surgery and without surgery. Methods: 24 university students (means age: $23.48{\pm}2.89years$) without refractive surgery (12, control group) and with refractive surgery (LASIK: 8, LASEK: 4, experimental group) participated in the study. Mean refractive errors of right eyes were -2.73 D for control group and -0.24 D for experimental group. The differences in the refractive power and corneal topography map between pre- and post-wearing the -3.00 D lenses were compared, and 2 kinds of hydrogel contact lenses (0.89 Mpa, 0.49 Mpa) and 2 kinds of silicone hydrogel lenses (1.5 Mpa, 0.8 Mpa) were used for -3.00 D lenses. NVision-K5001 (Shin nippon, Japan) was used to measure the refractive power and Keratograph 5M (Oculus, Germany) to measure the corneal topography map change. Results: Variations in the refractive power increased to the plus direction in the experimental group after wearing soft contact lenses. The corneal topography map showed significant changes on the both groups after wearing soft contact lenses (p<0.05). However there were no significant differences in the refractive power and corneal topography map variations by lens materials. Conclusions: Wearing soft contact lenses showed corneal topography map changes. Especially wearing soft contact lenses on the flat cornea after corneal refractive surgery showed greater corneal power changes. Therefore, it should pay attention to refractive change in case of prescribing soft contact lenses to patients with corneal refractive surgery.

• Journal of Korean Ophthalmic Optics Society
• /
• v.19 no.4
• /
• pp.551-555
• /
• 2014

Purpose: This study is to investigate if the improvement of visual sensory (VS) by amblyopia treatment affects the ocular functions in refractive errors, accommodative errors and phoria at distance and near. Methods: 10 subjects (17 eyes, mean age of $10.7{\pm}2.9$ years) who treated amblyopia completely, were participated for this study. Refractive errors, accommodative errors, and distance and near phoria were compared between before and after treatments of amblyopia. Refractive errors and accommodative errors at 40 cm were measured using openfield auto-refractor (NVision-5001, Shin Nippon, Japan) and using monocular estimated method (MEM) respectively. Phoria was determined at 3 m for distance and at 40 cm for near using Howell phoria card, cover test or Maddox rod. Results: Mean corrected visual acuity (CVA) significantly increased from $0.46{\pm}0.11$ (decimal notation) for before amblyopia treatment to a level of $1.03{\pm}0.13$ for after amblyopia treatment (p < 0.001). For spherical refractive error, hyperopia significantly decreased from $+2.29{\pm}0.86D$ to a level of $+1.1{\pm}2.38D$ (p < 0.05) but astigmatism did not significantly change; $-1.80{\pm}1.41D$ for before treatment and $-1.65{\pm}1.30D$D for after treatment (p > 0.05). Accommodative error significantly decreased from accommodative lag of $+1.1{\pm}0.75D$ to a level of $+0.5{\pm}0.59D$ (accommodative lag) (p < 0.05). Distance phoria significantly changed from eso $2.9{\pm}6.17PD$ (prism diopters) to a level of eso $0.2{\pm}3.49PD$ (p < 0.05), and near phoria also significantly changed from eso $0.4{\pm}2.32PD$ to level of exo $2{\pm}4.9PD$ (p < 0.05). There was a high correlation (r = 0.88, p < 0.001) between improvement of visual acuity and decrease of accommodative lag. Conclusions: Hyperopic refractive error decreased with improvement of CVA or VS by amblyopia treatment. And the improvement of VS by amblyopia treatment also improved accommodative error, and changed phoria coupled with accommodation.

• Journal of Korean Ophthalmic Optics Society
• /
• v.16 no.3
• /
• pp.265-272
• /
• 2011

Purpose: The clinical usefulness of rotation evaluation using objective refraction in toric soft lenses fitting was investigated. Methods: Toric soft lenses were fitted for 32 subjects (64 eyes; mean age of 24.69 ${\pm}$ 1.65 years) with astigmatism and both eyes of each subject were fitted with toric soft lenses. Objective refraction-based lenses rotation was evaluated from refraction and over-refraction data by indirect calculating technique. These calculated data were compared with the measured data from slit lamp with direct measuring technique. Results: Orientation of toric soft lenses around zero position (within ${\pm}$ 5$^{\circ}$ vertical line) was investigated. The orientations to the direction of nose of measured and calculated values were 69.78% and 63.64%, respectively, which showed similar values between two techniques. Agreement frequency between measured and calculated values in the magnitude of lenses rotation 54.69% and 82.82% for 10$^{\circ}$ and 20$^{\circ}$ of vertical line, respectively. The 95% limits of agreement between calculation and measurement were from -10.08$^{\circ}$ to 12.65$^{\circ}$, and mean difference was 1.29$^{\circ}$ within ${\pm}$ 10$^{\circ}$. The result showed there was no significant difference (p = 0.1984) and high correlation (r = 0.56, p = 0.0004) between two techniques. But the 95% limits of agreement was widen in ${\pm}$ 20$^{\circ}$ of vertical line. The magnitude of lens rotation between two methods was 9.66 ${\pm}$ 6.16$^{\circ}$, 16.17 ${\pm}$ 12.38$^{\circ}$ and 10.58 ${\pm}$ 12.02$^{\circ}$ for normal, loose and tight fitted conditions. Conclusions: From the results with smaller difference between two techniques, it was found that higher availability of subjective over-refraction data can be used as a supplementary tool for subjective refraction. An application using objective refraction with direct measuring could be provide high success in prescription on toric soft lenses.

• Journal of The Korean Ophthalmological Society
• /
• v.59 no.11
• /
• pp.1009-1016
• /
• 2018

Purpose: To assess the effect on axial elongation and associated factors between spectacles and of orthokeratology lens (OK) wearing in children with mild to moderate myopia. Methods: A total of one hundred subjects, ranging in age from 6 to 13 years, and with mild to moderate myopia no more than -4.50 diopters in spherical equivalent, visited our clinic from 2013 to 2015. The OK group (75 eyes) and the spectacles group (64 eyes) were compared and analyzed on the axial elongation and associated factors. Results: In the OK group, axial length was elongated in 1 year period with a mean increase of $0.24{\pm}0.29mm$. In spectacles group, axial length was elongated in 1 year period with a mean increase of $0.42{\pm}0.20mm$. The statistically significant suppression of axial elongation was observed in OK group compared to the spectacles group (Mann-Whitney U test, p < 0.05). For OK group, the age of starting OK (Pearson's correlation, r = -0.481, p < 0.05) was the only influencing factor on axial elongation, which had negative correlation with axial elongation. In spectacles group, the age of starting spectacles had negative correlation with axial elongation (Pearson's correlation, r = -0.462, p < 0.05) and baseline spherical equivalent, spherical diopter, cylindrical diopter from manifest refraction had positive correlation with axial elongation. Comparison of axial elongation in orthokeratology lens group and spectacles group by age groups (6 to 9 years [28 eyes], 9 to 13 years [47 eyes]), 9 to 13 years of orthokeratology lens group had the stronger suppression of axial elongation (Mann-Whitney U test, p < 0.05). Conclusions: The OK effectively suppresses axial elongation compared to the spectacles. Although the patients are in age from 9 to 13 years, the axial elongation was effectively suppressed.