PURPOSE: To know the factors associated with the posterior corneal surface elevation in myopic eye. METHODS: The posterior corneal surface elevation (PCSE), keratometry, central corneal thickness (CCT), peripheral corneal thickness (PCT), thinnest corneal thickness (TCT) were measured in 64 right myopic eyes with the Orbscan topography system. The correlation between PCSE and age, refractive error, intraocular pressure (IOP), keratometry, CCT, TCT, PCT, PCT-CCT, PCT/CCT, PCT-TCT, and PCT/TCT was evaluated. RESULTS: The posterior corneal surface elevation has correlation with CCT (r:.0.3306, p:0.0071), TCT ( r :.0.4094, p:0.0007), PCT-CCT(r:0.3326, p:0.0068), PCT/CCT (r:0.3759, p:0.0020), PCT-TCT (r: 0.4750, p:0.0001), and PCT/TCT (r:0.5145, p:0.0001) but does not have correlation with age, keratometry, refractive error, IOP (r:.0.0627, p:0.6225), and PCT. CONCLUSIONS: In myopic eyes, the posterior corneal surface elevation correlates with central corneal thickness and specifically the ratio PCT to TCT.
Intraocular Pressure ; Refractive Errors

The thirty four patients(60 eyes) of the same age group, sex and refractive error receiving eximer laser photorefractive keratectomy(PRK) from April 2, 1991 to May 2, 1993 were studied to evaluate the possible factors influencing the myopic regression. In this study, we didn't find any difference between regressed and nonregressed group in the individual parameters such as IOP, keratometer, corneal thickness, occupation, surgeon, hyperopic peak after PRK, and topographic analysis preoperatively and postoperatively. But, the increased tendency of myopic regression one the another eye experiencmg myopic regression on one eye showed statistically significance(P=0.005) and the same tendency was applied on the corneal haziness(P=0.012). We suggest corneal haziness is likely related to causing the myopic regression following PRK. Therefore, the surgeon should particularily try to prevent myopic regression in patients experiencing myopic regression on his one eye by minimizing coneal haziness following PRK.
Humans ; Occupations ; Refractive Errors

PURPOSE: To evaluate the accuracy of the SRK II formula for the AMO Array(R) multifocal intraocular lens (Array lens) power calculation according to axial length. In case of refractive error more than +/- 1.0 diopter (D), we compared the accuracy of the SRK II with that of other formulas. METHODS: Participants were 178 eyes (142 patients) received the Array lens. These were divided into 3 subgroups based on axial length. Group I had 21 eyes of short axial length (less than 22.0 mm). Group II had 133 eyes of average axial length (more than 22.0mm below 24.5mm). Group III had 24 eyes of long axial length (more than 24.5mm). The difference between preoperative predicted refractive value and postoperative manifest refractive value were calculated. We compared the accuracy of the SRK II and that of SRK/T, Holladay formulas in case of refractive error more than +/- 1.0D. RESULTS: Three eyes (14.2%) in Group I, 14 eyes (10.5%) in group II and 15 eyes (62.5%) in Group III showed refractive errors more than +/- 1.0D. Fifteen eyes (62.5%) in Group III were significantly reduced to 7 eyes (29.1%) with using SRK/T, Holladay formulas. CONCLUSIONS: SRK II formula had better predictive accuracy in axial length less than 24.5mm with Array lens. But it is better to apply SRK/T or Holladay formulas when axial length is more than 24.5mm.
Lenses, Intraocular* ; Refractive Errors*

The authors reported a high incidence of astigmatism and longer axial length in cases of unilateral congenital ptosis. But post-operative changes of refraction and axial length were still obscure. In this reason we analysed on axial length operation. Post-operative refractive errors between ptotic and normal eyes were similar without significant differences(p=0.38). But the incidence of astigmatism in the ptotic eyes was higher(72% vs 32%) and amounts of astigmatism was also increased in the ptotic eye with statistically significant(-1.25 +/-0.49 vs 0.56+/-0.66D, p=0.04). Pre-operative axial lengths for ptotic eyes was longer than those of healthy eyes (22.80+/-1.46 vs 22.64+/-1.40mm, p=0.029) but postoperative axial lengths between ptotic and normal eyes were similar(23.26+/-1.63mm vs 23.28+/-1.60, p=0.87). As results of above, wer concluded that axial lengths of unilateral ptotic eye were similar to those of healthy eye but incidence of astimatism was higher in cases of unilateral congenital ptosis after one year of operation for ptosis.
Astigmatism ; Incidence ; Refractive Errors*

PURPOSE: The present study assessed the influence of overnight orthokeratology (ortho-k) on the myopic progression in Korean children and analyzed factors affecting myopic progression. METHODS: The ortho-k group was comprised of 31 patients satisfying the inclusion criteria for ortho-k. In the ortho-k group, spherical equivalent refractive error (SER) was measured at baseline, and after 2 weeks, 6 and 12 months. The control group was comprised of 31 patients who were matched according to age, gender, and baseline SER of the ortho-k subjects. RESULTS: In the ortho-k group, the mean +/- SD changes in SER from 2 weeks to 6 months, 6 to 12 months, and 2 weeks to 12 months were -0.17 +/- 0.50 D, -0.04 +/- 0.76 D, and -0.21 +/- 0.78 D, respectively. In the control group, the changes in SER from baseline to 6 months, 6 to 12 months, and baseline to 12 months were -0.38 +/- 0.42 D, -0.44 +/- 0.38 D, and -0.82 +/- 0.68 D, respectively. Significant differences were found between changes in SER from 6 to 12 months and from baseline to 12 months (p < 0.05). In the ortho-k group, relationships between the changes of SER for 1 year and the numeric values of baseline measurements were analyzed. When comparing the results between the group of SER change > or = -0.5 D with the group of SER change < -0.5 D, numeric values of white-to-white diameters of the 2 groups were different, and a significant correlation was found between the range of SER change and the white-to-white diameter (Pearson's r = -0.471, p = 0.008). CONCLUSIONS: Ortho-k is effective for slowing myopic progression. The smaller the white-to-white diameter, the slower the myopic progression could be.
Child ; Humans ; Refractive Errors

556 Monocular blinded men were observed, and results were as following. 1) 500 patients (89.9%) had visuial acuity of 20/20 or better in the fellow eye. 2) 56 patients (10.1%) were ametropia.
Humans ; Male ; Refractive Errors

The objects of the refractive examination are to check the refractive state of the eyes and to correct the refractive errors with glasses. This paper is directed to the basic methods of subjective and objective refractive examination.
Eyeglasses ; Glass ; Refractive Errors

PURPOSE: We investigated reproducibility and repeatability of average macular thickness and volume measurements in normal eyes with Cirrus HD OCT (optical coherence tomography). METHODS: Fifty normal eyes from twenty-five subjects without medical and ocular histories were included. Macular cube 512 x 128 combination scanning using the Cirrus HD OCT was performed for a total of three times on the same visit by an experienced technician. Then other two technicians performed one more macular scanning respectively. Within-results, the intraclass correlation coefficient (ICC) was calculated for each parameter studied to evaluate repeatability and reproducibility. The correlation between macular measurements and demographic variables (age, gender, and spherical equivalent) were also investigated. RESULTS: The ICCs for intraoperator reproducibility were 0.99 on the average macular thickness and 0.96 on the macular volume. And the ICCs for interoperator repeatability were found to be 0.98 and 0.96, respectively. The ICCs for measurements of nine regional retinal thickness also were higher than 0.90. The retinal thickness was correlated with age, gender and refractive error. However, neither age nor refractive error affected to reproducibility and repeatability. CONCLUSIONS: The retinal thickness and macular volume measurements using Cirrus HD OCT in healthy volunteers showed excellent reproducibility and repeatability. Therefore, Cirrus HD OCT has been recognized as an useful tool for diagnosis and mornitoring of variable maculopathies.
Eye ; Refractive Errors ; Retinaldehyde

PURPOSE: To compare the myopic progression before and after wearing an orthokeratology lens (OK). METHODS: Twenty-six patients (49 eyes) with at least 6 months of myopia prior to OK treatment were evaluated. Changes in the spherical equivalent (SE) refractive error and axial length were compared before and after OK use. Changes in the SE and axial length were also compared between two groups according to the myopic progression before baseline: Group 1 with myopic progression < 1 D/year and Group 2 with myopic progression > 1 D/year. RESULTS: The myopic progression rate decreased from −1.1 to −0.3 D/year after OK treatment (p < 0.001). Greater increases in axial length were observed in patients who were younger and had less myopia at baseline, a higher rate of myopia progression before baseline, and a shorter axial length at baseline (p < 0.001, p < 0.004, p < 0.007, and p < 0.001, respectively). The increase in axial length was significantly greater in the group with greater myopic progression before baseline (0.2 mm/year) than in the group with less myopic progression (0.1 mm/year) (p = 0.001). CONCLUSIONS: Myopic progression was reduced significantly after OK treatment.
Humans ; Myopia ; Refractive Errors

We analysed the relationship between preoperative factors and changes of corneal thickness after LASIK.Between January 1997 and October 1998, 124 eyes underwent LASIK procedure using VISX STAR at Kangnam's St. Mary's hospital.In group 1, 39 eyes had corneal thickness 50 micrometer or more after preoperative corneal thickenss was substracted with postoperative thickness.As control group, 33 eyes had the difference of corneal thickness 0 -5 0 micrometer or less.The each difference was calculated at 1 wk, 1 month, 6 months, 1 year postoperatively.We evaluated the preoperative factors, such as corneal thickness, spherical equivalent, corneal keratometer.The attempted correction for refractive errors was determined by cycloplegic refraction.In group 1, the difference in corneal thickness was 77 +/-2.5 micrometer at 1 week.58 +/-1.4 micrometer at 2 months, 57 +/-1.2 micrometer at 6 months and 58 +/-1.4 micrometer at 1year postoperatively. These results statistically greater than those of control group.And the more spherical equivalent, the thinner corneal thickness, the more difference in corneal thickness was, which was statistically signifi-cant comparing with group 2 (P<0.05).But, preoperative keratometry and the difference in corneal thickness was not significant between two groups (P=0.64).
Keratomileusis, Laser In Situ* ; Refractive Errors