• Kosin Medical Journal
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• v.33 no.3
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• pp.318-327
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• 2018

Objectives: To investigate the effect of absorbable suture on surgically-induced corneal astigmatism in 3.0-mm sclera tunnel cataract surgeries. Methods: Medical records of patients who underwent phacoemulsification cataract surgery using a 3.0-mm sclera tunnel incision made by a single surgeon were reviewed. Uncorrected distant visual acuity, corneal astigmatism and surgically-induced astigmatism were measured in 56 patients' eyes that underwent sclera tunnel cataract surgery with absorbable sutures (sutured group) and in 23 patients' eyes without sutures (unsutured group). Uncorrected visual acuity, intraocular pressure, slit lamp examination, and automated keratometry were evaluated preoperatively and at 3 days, 2 weeks, 4 weeks, and 8 weeks after cataract operation. Results: There were no significant differences in preoperative average uncorrected distant visual acuity of the two groups (sutured group: $0.79{\pm}0.64$, unsutured group: $0.68{\pm}0.72$, P = 0.145). Corneal astigmatism measured using keratometry in the sutured and unsutured group at postoperative day 3 were $2.27{\pm}2.12D$ versus $0.83{\pm}0.55D$ at (P < 0.001), a difference which had disappeared after 4 weeks. Surgically induced astigmatism using the Holladay and Vector methods showed similar outcomes, suggesting that the sutured group exhibited higher astigmatism compared with the unsutured group until 2 weeks post-surgery. Conclusions: TPatients undergoing scleral tunnel cataract surgery with absorbable sutures have greater surgically induced astigmatism, especially in the early postoperative period, compared with those without sutures. However, this surgically induced astigmatism due to absorbable sutures in scleral tunnel cataract surgery is temporary and disappears at 4 weeks post-surgery.

• 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 The Korean Ophthalmological Society
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• v.60 no.2
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• pp.126-134
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• 2019

Purpose: To assess the accuracy of toric intraocular lens (IOL) implantation by the location and size of the corneal incision. Methods: We retrospectively reviewed the medical records of 98 patients (98 eyes) who underwent phacoemulsification with toric IOL implantation from January 2014 to March 2017. The patients were divided into two groups: group 1 got an incision of the superior side of the cornea (n = 54) and group 2 received an incision on the temporal side of the eye (n = 44). For both groups, incisions were made at their steep corneal astigmatism axises. Each group was further divided into subgroups for whom different sized blades were employed (2.75 vs. 2.2 mm widths). We measured the refractive index and autokeratometric parameters. We postoperatively assessed residual astigmatism and any reduction thereof. Results: In both groups, uncorrected and best-corrected visual acuity, refraction cylinder astigmatism, and autokeratometric astigmatism improved statistically. Between two groups, corneal astigmatism decrease was not significant. Residual astigmatism also showed no significant differences between the two. Patients in both groups treated using 2.75 mm wide blades exhibited greater increases in corneal astigmatism. Conclusions: During cataract surgery, precise correction of astigmatism via toric IOL implantation is possible when surgically induced astigmatism is minimized by careful choice of the location and size of the corneal incision.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.3
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• pp.271-277
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• 2013

Purpose: The purpose was to study the corneal refractive power changes associated with the wearing of everted silicone hydrogel soft lenses. Methods: The corneal refractive power and corneal astigmatism were measured using corneal topographer (CT-1000, Shin-nippon Co., Japan) for checking change of corneal refractive power and objective refractive error was measured by auto-refractometer (Natural vision-K 5001, Shin-nippon Co., Japan). We measured at baseline and 1 week after lens wearing. Results: The correcting of corneal refractive power could be effective in low myopia. It's more effective to the higher power of greatest meridian of cornea and the more corneal astigmatism. 73% of subjects' refractive error was decrease less than 1 D and 17% of the subjects had an reverse effect (increase) occurs. The reduction of objective refractive error was more effective when cornea refractive power was great or corneal astigmatism was much. Conclusions: Pressure which the everted silicone hydrogel lens to the cornea could be caused. It occurred as the degrees of corneal power, corneal astigmatism and objective refractive error differences. Selection of an appropriate subject is important considering difficulty of changing the parameters of the lens.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.2
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• pp.141-150
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• 2015

Purpose: In the present study, a difference in tear volume between the cornea and the rigid gas permeable (RGP) lens relative to corneal shape and corneal astigmatism was investigated by the alignment fitting status of spherical and aspherical RGP lenses. Methods: Spherical and aspherical RGP lenses were fitted with alignment in 77 subjects (135 eyes) who were in their 20~30s. Tear volume stained with fluorescein was qualitatively analyzed by dividing cornea into center, mid-peripheral and peripheral parts. Results: For the spherical RGP lens fitting, tear volume differences were found in each part in all corneal types. For the aspherical RGP lens fitting, tear volume differences were in each corneal part in symmetric bow tie- and asymmetric bow tie-type corneas. However, the tear was equally distributed from the center to the peripheral part in round- and oval-type corneas. In the group with corneal astigmatism lower than 1.25 D, tear volume between center and peripheral parts, and mid-peripheral and peripheral parts, was different when a spherical RGP lens was fitted. However, tear volume in each part was not different in the group with corneal astigmatism over 1.50 D. Moreover, the tear volumes of the central and mid-peripheral parts were proportionally increased with increasing corneal astigmatism in both spherical and aspherical RGP lenses. Furthermore, aspherical RGP lenses showed greater increments than spherical RGP lenses. Conclusions: The results revealed that the difference in tear volume between aspherical RGP lens and cornea was less than spherical RGP lens, and the difference in tear volume varied according to corneal shape and astigmatism. In addition, the method of measuring relative tear volume between RGP lens and cornea that was established in the present study can be used to evaluate tear volume between contact lens and cornea.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.2
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• pp.27-31
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• 2000

As the functional test of cornea. The clinical value of keratometric information was important for assessment the curvature of the cornea, the quality of the corneal surface, the stability of the corneal curvature, and the direction of the corneal astigmatism. This study was performed the comparative analysis of male and female of adult on the base curve, power and astigmatism of the Cornea. On the corneal base curve, the male right eye was 7.656 mm in vertical and 7.966 mm in horizontal. But, the male left cornea was 7.714 mm in vertical base curve and 8.026 mm in horizontal base curve. On the other hand, the female right eye cornea was 7.559 mm in vertical base curve and 7.695 mm in horizontal base curve. But, the female left eye cornea was 7.444 mm in vertical base curve and 7.742 mm in horizontal base curve. On the corneal diopter power, the male right eye was 44.063 diopter in vertical and 43.738 diopter in horizontal. But the male left eye was 44.046 diopter in vertical and 42.304 diopter in horizontal. On the other hand, the female right eye was 44.082 diopter in vertical and 43.77 diopter in horizontal. But, the female left eye was 44.347 diopter in vertical and 43.495 diopter in horizontal. According to the corneal astigmatism axis. The male right eye have 89.9% positive for with the - rule astigmatism, and 8.1 % positive for against - the - rule astigmatism. But, he male left eye have 91.89% positive for with - the - rule astigmatism, and 8.11 % positive for against - the - rule astigmatism. On the other hand, The female right eye have 76.92% positive for with - the - rule astigmatism, and 23.08 % positive for against - the - rule astigmatism. But, the female left have 80.76 % positive for with - the - rule astigmatism, and 17.31 % positive for against - the - rule as tigmatism. The diopter power of corneal astigmatism have 25.57% positive for behind 1 diopter, 44.89% positive for 1 diopter, 18.18% positive for 2 diopter, 5.11% positive for 3 diopter and 6.25% positive for over 4 diopter.

• 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.17 no.4
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• pp.469-476
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• 2012

Purpose: The purpose of this study is to investigate the changes of asphericity according to diameter and direction of the cornea. Methods: The changes of asphericity according to diameter and direction of cornea is measured by using Pentacam(Oculus Co., Germany), as targeting 57 adults (average $27.0{\pm}4.8$, 20 men, 37 women) without any ophthalmic diseases, which may be effective in eyesight, and refractive surgery. Results: As diameter increases in every direction based on the corneal vertex, asphericity has attentively increased (p<0.05), and the size of asphericity in each direction from every measured diameter showed as superior > nasal > inferior > temporal. In group comparison by nearsightness and astigmatism level, asphericity measured high when nearsightness and astigmatism levels were higher, and this appears to be statistically attentive.(p<0.05). Conclusions: Asphericity of cornea significantly increased according to increase of diameter of cornea, and as measured figure or increased quantity appeared differently in all directions based on corneal vertex, so it helps to understand shape of cornea, and considered that is the part to be considered during manufacturing and fitting of RGP lenses.

• Medical Lasers
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• v.10 no.4
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• pp.229-237
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• 2021

Background and Objectives To assess the effectiveness of overnight orthokeratology (OK) in myopia using a new contact lens design over a one-month wearing period. Materials and Methods Participants were required to have myopia between -3.00 and -7.50D and astigmatism ≤ 2.00 D to participate in the study. The participants underwent OK with the White OK lens^® (Interojo, Pyungtek, Korea), which has a 6-curve lens design. Participants were assessed at weeks 1, 2, and 4 using slit-lamp bio-microscopy, and tested for refraction, uncorrected distance visual acuity, and corneal topography. Success was defined as achieving a Logarithm of the Minimum Angle of Resolution (logMAR) ≤ 0.1. Results A total of 46 eligible subjects with a mean age of 23.11 ± 7.89 years were recruited. Baseline logMAR was 1.18 ± 0.30 and a consistent decrease in logMAR was observed from week 1 to week 4. The success rate was 95.35% at week 4. The mean sphere significantly decreased from a mean pre-fitting value of -4.58 ± 1.28 D to a mean value of -0.65 ± 0.69 D at week 4 (p < 0.0001). Statistically significant corneal flattening was detected during keratometry at week 4. Conclusion Overnight OK with the White OK lens is effective for the correction of moderate and high myopia with astigmatism over a one-month wearing period.

• 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.