PURPOSE: We compared and analyzed central corneal thickness (CCT) measurements according to the corneal thickness obtained with noncontact specular microscopy (NCSM) and ultrasound pachymetry (USP). METHODS: CCT was measured in the order of NCSM and USP by a single optometrist in 120 eyes of 120 healthy subjects. The measurements were compared between the devices and the measurement agreements and correlations between the devices were analyzed. To determine if the measurements differed depending on the thickness of the cornea, the patients were divided into three tertile groups from the thinnest patient by CCT measurement using USP, and then the differences in CCT measured by the two devices were analyzed. RESULTS: The CCT measurements using NCSM and USP were 548.25 ± 4.64 µm and 533.09 ± 35.96 µm, respectively. NCSM measurements were found to be thicker, showing statistically significant differences between the measurements (p < 0.001). The two examinations showed a high degree of correlation (r = 0.878; p < 0.01). In the three groups, the differences in CCT measurements between NCSM and USP were 12.93 ± 21.88 µm, 16.85 ± 15.89 µm, and 15.70 ± 20.46 µm, respectively, but the differences between the three groups were not statistically significant (p = 0.655). CONCLUSIONS: Our results show that although the differences in CCT measurements using NCSM and USP were consistent regardless of the corneal thickness, the CCT measurements by NCSM and USP were highly correlated.
Cornea ; Corneal Pachymetry ; Healthy Volunteers ; Humans ; Microscopy ; Ultrasonography

PURPOSE: To assess the validity of central corneal thickness (CCT) and corrected intraocular pressure (IOP) values obtained by tono-pachymetry in non-surgical and post-photorefractive keratectomy (PRK) eyes. METHODS: For the study, 108 young healthy participants and 108 patients who had PRK were enrolled. Measurements were randomly performed by tono-pachymetry, ultrasonic (US) pachymetry, and Goldmann applanation tonometry (GAT). CCT measurement by tono-pachymetry was compared to that of US pachymetry. The corrected IOP value obtained by tono-pachymetry was compared to that obtained by US pachymetry and GAT. The corrected IOP from US pachymetry and GAT was calculated using the identical compensation formula built into the tono-pachymetry. Bland-Altman plot and paired t-test were conducted to evaluate the between-method agreements. RESULTS: The mean CCT measurement using tono-pachymetry was significantly greater by 7.3 µm in non-surgical eyes (p < 0.001) and 17.8 µm in post-PRK eyes (p < 0.001) compared with US pachymetry. Differences were significant in both Bland-Altman plotand paired t-test. The mean difference of corrected IOP values obtained by tono-pachymetry and calculated from measurements by US pachymetry and GAT was 0.33 ± 0.87 mmHg in non-surgical eyes and 0.57 ± 1.08 mmHg in post-PRK eyes. The differences in the Bland-Altman plot were not significant. CONCLUSIONS: The CCT measurement determined using tono-pachymetrywas significantly thicker than that of US pachymetry. The difference in CCT was greater in post-PRK eyes than in non-surgical eyes. However, the corrected IOP value obtained by tono-pachymetry showed reasonable agreement with that calculated from US pachymetry and GAT measurements.
Compensation and Redress ; Corneal Pachymetry ; Healthy Volunteers ; Humans ; Intraocular Pressure* ; Manometry ; Photorefractive Keratectomy ; Ultrasonics

PURPOSE: The aim of this study was to investigate the differences in anterior segment ocular parameters in anisometropia >1 D. METHODS: This study included 202 eyes of 101 subjects ranging from 10 to 40 years of age with anisometropia of 1 D or more. The subjects were divided into groups according to anisomyopia, anisoastigmatism, and anisohypermetropia. After providing informed consent, each patient underwent a detailed ophthalmological examination including cycloplegic refraction, best-corrected visual acuity, cover test, axial length (AL) measurement using A-scan ultrasound biometer, keratometry, anterior chamber depth, and central corneal thickness measurement. For each participant, the eye with greater refractive error was compared to the fellow eye via paired t-tests. Correlations between parameters were studied using the Pearson correlation coefficient. RESULTS: The average age of subjects was 21.7 ± 9.3 years. Of 101 subjects, 31 had anisomyopia; 42 had anisohypermetropia; and 28 had anisoastigmatism. A predisposition toward greater myopia in right eyes was noted in anisomyopia (24 of 31 subjects, 77%). The inter-ocular acuity difference was significant in all three groups (p < 0.01). As the degree of anisometropia increased, there was significant positive correlation in the difference in AL in myopes (r = 0.863, p < 0.01) and hypermetropes (r = 0.669, p < 0.01) and the difference in corneal curvature in anisoastigmatism (r = 0.564, p = 0.002) and hypermetropes (r = 0.376, p = 0.014). A significant positive correlation was also present between the anterior chamber depth difference and refractive difference in hypermetropes (r = 0.359, p = 0.020). CONCLUSIONS: This study showed that anisomyopia is correlated only with anterior chamber differences. Anisohypermetropia is correlated with AL differences as well as corneal curvature difference and anterior chamber depth difference. The amount of anisoastigmatism correlates only with corneal curvature difference.
Anisometropia* ; Anterior Chamber ; Cimetidine ; Corneal Pachymetry ; Humans ; Informed Consent ; Myopia ; Prospective Studies* ; Refractive Errors ; Ultrasonography ; Visual Acuity

PURPOSE: To compare the measurements of central corneal thickness (CCT) obtained using two kinds of spectral domain optical coherence tomography (OCT), Pentacam®, and ultrasound pachymetry (USP). METHODS: CCT was measured by Cirrus OCT®, Spectralis OCT®, Pentacam®, and USP in 32 eyes from 32 subjects without ocular disease of the anterior segment. RESULTS: The average CCT measurements using Cirrus OCT®, Spectralis OCT®, Pentacam®, and USP were 549.2 ± 28.7 µm, 545.2 ± 25.4 µm, 554.0 ± 27.8 µm, and 548.4 ± 27.9 µm respectively. The measurements were significantly highly correlated with each other (Pearson's correlation coefficient r > 0.9, all p-values < 0.001), but were significantly different (p < 0.001). The CCT 95% limits of agreement between Cirrus OCT® and Spectralis OCT®, Cirrus OCT® and Pentacam®, Cirrus OCT® and USP, Spectralis OCT® and Pentacam®, and Spectralis OCT® and USP were 27.70 µm, 26.1 µm, 26.97 µm, 22.91 µm, 35.59 µm, and 32.15 µm, respectively. CONCLUSIONS: The CCT values measured using the four devices were highly correlated with each other, but the measurement using Pentacam® was significantly thicker than that using USP. The measurements of the two kinds of spectral domain OCT were similar to those using USP. Therefore, these differences should be considered in clinical use, and measurements cannot be considered interchangeable.
Corneal Pachymetry* ; Tomography, Optical Coherence* ; Ultrasonography*

PURPOSE: To compare the accuracy and agreement of intraocular pressure (IOP) and central corneal thickness (CCT) measurements with noncontact tonometer Corvis Scheimpflug Technology (Corvis ST) versus noncontact tonometer (NCT), Goldmann applanation tonometer (GAT), rebound tonometer (RBT), and ultrasound-based corneal pachymetry (US-CCT). The secondary objective was to evaluate the corneal biomechanical values using Corvis ST tonometer in patients with glaucoma. METHODS: Thirty-one healthy participants and 47 patients with primary open angle glaucoma and normal tension glaucoma were enrolled in this study. One eye was selected randomly. In each participant, GAT, NCT, RBT, US-CCT and measurements with Corvis ST (Corvis-IOP and Corvis-CCT) were obtained. IOP and CCT measurements of each device were compared. Device agreement was calculated by Bland-Altman analysis. Additionally, corneal highest concavity parameters were compared between healthy subjects and glaucoma patients. RESULTS: Mean IOPs in all examined eyes were 13.28 +/- 2.32 mm Hg for CST, 14.71 +/- 2.95 mm Hg for GAT, 14.44 +/- 3.10 mm Hg for NCT, and 13.23 +/- 2.89 mm Hg for RBT. There was no statistical difference in IOP measurements among tonometers. Correlation analysis showed a high correlation between each pair of tonometers (all p < 0.0001). Bland-Altman plots of all devices revealed good agreement of the IOP and CCT measurements. In glaucoma patients, highest concavity time and peak distance of highest concavity parameters were statistically lower than in normal subjects (16.93 +/- 0.66 ms vs. 16.48 +/- 0.84 ms p = 0.020, 4.23 +/- 1.34 mm vs. 3.41 +/- 1.27 mm p = 0.017, respectively). CONCLUSIONS: The CST, a newly-developed tonometer with features of visualization and measurement of the corneal deformation response to an air impulse, can be considered a reliable alternative method for measuring IOP and CCT in healthy subjects and glaucoma patients. Highest concavity parameters could be another important indicator identifying corneal viscosity or elasticity in patients with glaucoma.
Corneal Pachymetry ; Elasticity ; Glaucoma ; Glaucoma, Open-Angle ; Humans ; Intraocular Pressure ; Low Tension Glaucoma ; Viscosity

PURPOSE: To evaluate the natural course of the long-term endothelial cell changes in Fuchs corneal dystrophy (FCD) patients and investigate the effects of phacoemulsification on the annual rate of change in endothelial indices in FCD patients. METHODS: Thirty-four patients diagnosed with FCD at Seoul National University Hospital from 1994 to 2010 were retrospectively reviewed. Sixteen patients who had been followed up for more than 1 year were selected and classified into 3 groups: group A, patients with no ocular surgery; group B, patients who had undergone phacoemulsification only; and group C, patients who had undergone penetrating keratoplasty with cataract surgery. Endothelial cell density, polymegethism, pleomorphism, and pachymetry were measured and the exponential rates of endothelial cell and pachymetry change were analyzed. RESULTS: A non-linear mixed model of non-operated FCD patients showed that only pachymetric data tended to increase with statistical significance (p = 0.001) with a mean follow-up period of 4.15 years. Using an exponential regression analysis fitting curve, the mean rates of annual endothelial cell loss were 0.82%/yr, 20.39%/yr, and 29.27%/yr in groups A, B, and C respectively, and statistical significance was seen only in group C (p < 0.05). CONCLUSIONS: Retrospective long-term follow-up data showed that changes in endothelial density did not significantly decrease over at least 4 years in middle-aged FCD patients. The changes in pachymetric corneal thickness appeared to increase over the same period. Considering that no exponential changes were aggravated after performing cataract surgery alone, cataract surgery would be a preferable option in FCD patients compared to an approach of "wait-and-do" penetrating keratoplasty combined with cataract surgery.
Adult ; Aged ; Aged, 80 and over ; Cataract/*complications/pathology ; Cell Count ; Corneal Pachymetry ; Disease Progression ; Endothelium, Corneal/*pathology ; Female ; Follow-Up Studies ; Fuchs' Endothelial Dystrophy/complications/*pathology/surgery ; Humans ; *Keratoplasty, Penetrating ; Male ; Middle Aged ; *Phacoemulsification ; Postoperative Period ; Retrospective Studies ; Time Factors ; Young Adult

PURPOSE: To compare the intraocular pressure (IOP), retinal nerve fiber layer (RNFL) thickness and central corneal thickness (CCT) in healthy individuals and patients with chronic renal failure (CRF) undergoing hemodialysis, and to evaluate the changes in each parameter before and after hemodialysis in patients with CRF. METHODS: Thirty-six eyes of 36 patients with CRF undergoing hemodialysis were included in the hemodialysis group and 54 eyes of 54 healthy subjects were recruited as the control group. All subjects underwent a complete eye examination, including best-corrected visual acuity (BCVA), slit lamp examination, dilated funduscopic examination, gonioscopy, automated perimetry, IOP measurement, corneal pachymetry, and evaluation of RNFL thickness. In the hemodialysis group, IOP, RNFL thickness, and CCT were measured again within 1 hour of hemodialysis. RESULTS: Age, sex, BCVA, cup-to-disc ratio, IOP, and CCT were not statistically different between the 2 groups. The RNFL of the hemodialysis group was statistically significantly thinner than the control group (p < 0.001). The IOP decreased from 16.52 +/- 2.95 mm Hg to 14.88 +/- 2.03 mm Hg after hemodialysis (1.63 +/- 3.27 mm Hg; p = 0.005). The changes in RNFL thickness and CCT were not statistically significant (p = 0.148, p = 0.352). CONCLUSIONS: In CRF patients with hemodialysis, RNFLs were thinner in the control group and hemodialysis induced significant IOP reduction. The results from the present study should be considered for the proper evaluation of ocular disorders in CRF patients with hemodialysis.
Corneal Pachymetry ; Eye ; Gonioscopy ; Humans ; Intraocular Pressure ; Kidney Failure, Chronic ; Nerve Fibers ; Renal Dialysis ; Retinaldehyde ; Visual Acuity ; Visual Field Tests

PURPOSE: To compare corneal pachymetry assessment using four measurement methods in normal and post-femtosecond laserassisted LASIK eyes. METHODS: Central corneal thickness was measured sequentially using Orbscan II, Pentacam, Galilei and ultrasonic pachymetry in 30 normal, non-surgical eyes (Group I), 30 eyes one to six months after femtosecond laser-assisted LASIK (Group II), and 30 eyes six months or longer after femtosecond laser-assisted LASIK (Group III). RESULTS: In Group I, corneal thickness measurements were similar for all four methods (P=0.202, one way ANOVA). In Groups II and III, corneal thickness measurements were significantly different (P=0.000, respectively, one way ANOVA). Compared to the Pentacam, Galilei and ultrasonic pachymetry, Orbscan significantly underestimated the corneal thicknesses in Groups II and III (P<0.005, respectively, one way ANOVA). CONCLUSIONS: Central corneal thicknesses of normal eyes were similar for all four measurements, therefore corneal thickness measurements before refractive surgery using all four measurements is suitable. However measurements obtained with the Orbscan II were thinner than those obtained with the Pentacam, Galilei or ultrasonic pachymetry in post femtosecond laserassisted LASIK eyes. Further studies are needed to determine which instrument is more accurate in measuring central corneal thickness before and after refractive surgery.
Corneal Pachymetry ; Eye ; Keratomileusis, Laser In Situ ; Refractive Surgical Procedures ; Ultrasonics

PURPOSE: To report a case of a familial lecithin cholesterol acyltransferase (LCAT) deficiency patient with bilateral corneal opacities. CASE SUMMARY: A 26-year-old man with bilateral corneal opacities visited our hospital. We took slit lamp examination, corneal thickness measurement, corneal endothelial cell counts and fundus examination. Blood and urine tests were included. Kidney biopsy was done. The tissues were observed by a light microscopy and an electron microscopy. Hemolytic anemia, proteinuria, hematuria, hypertriglyceridemia, decreased HDL cholesterol level, and lecithin cholesterol acyltransferase (LCAT) deficiency were found. At kidney biopsy, electron-lucent vacuoles and lamellar inclusion body were found. CONCLUSIONS: Bilateral corneal opacities can be an imporant clinical sign of systemic disease which is caused by abnormal lipid metabolism like the familial lecithin cholesterol acyltransferase (LCAT) deficiency.
Adult ; Anemia, Hemolytic ; Biopsy ; Cholesterol, HDL ; Corneal Opacity ; Corneal Pachymetry ; Endothelial Cells ; Hematuria ; Humans ; Hypertriglyceridemia ; Inclusion Bodies ; Kidney ; Light ; Lipid Metabolism ; Microscopy ; Microscopy, Electron ; Phosphatidylcholine-Sterol O-Acyltransferase ; Proteinuria ; Vacuoles

PURPOSE: To investigate the relationship among optical coherence tomography (OCT), ultrasound pachymetry, and Orbscan in central corneal thickness measurement and to evaluate the reproducibility of flap thickness using an IntraLase femtosecond laser. METHODS: Central corneal thickness was measured by OCT, ultrasound pachymetry, and Orbscan in 59 eyes of 30 patients before LASIK. After IntraLASIK, the corneal flap thickness measured using OCT was compared with the intended corneal flap thickness. RESULTS: Central corneal thickness measured by OCT was thinner than that measured by other instruments preoperatively, but there was no significant difference among these methods (p>0.01), and corneal thickness values obtained by ultrasound pachymetry and Orbscan correlated well with those obtained by OCT (r ranged from 0.804 to 0.889, p<0.01). After IntraLASIK, there was no significant difference between the mean measured flap thickness and the intended flap thickness (p>0.01). CONCLUSIONS: OCT is a relatively accurate instrument for measuring corneal thickness and can easily measure the corneal flap thickness after LASIK. Compared with the results of a previous study, the mean measured flap thickness in this study was more reproducible with the IntraLase femtosecond laser.
Corneal Pachymetry ; Humans ; Keratomileusis, Laser In Situ ; Tomography, Optical Coherence* ; Ultrasonography