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Purpose: To compare central corneal thickness (CCT) measured with optical coherence tomography (OCT) using an automatic algorithm (A-OCT) vs. manual measurements (M-OCT) with respect to the gold standard ultrasound pachymetry (USP). Methods: CCT measurements were performed on both eyes of 28 healthy subjects at four times of the day. A-OCT used an automatic software analysis of the corneal image, M-OCT was performed by two operators by setting a digital calliper on the corneal borders, and USP was performed after corneal anesthesia. Measurements were compared using a three-way repeated measures ANOVA. Bland–Altman plots were used to evaluate the agreement between OCT measurements and USP. Results: Both A-OCT and M-OCT significantly underestimated the USP measures, with the mean difference, i.e., the systematic error, being larger for A-OCT (− 19.0 µm) than for M-OCT (− 6.5 µm). Good reproducibility between the two operators was observed. Bland–Altman plots showed that both OCT methods suffered from proportional errors, which were not affected by time and eye. Conclusions: Measuring CCT with OCT yielded lower values than USP. Therefore, clinicians should be aware that corneal thickness values may be influenced by the measurement method and that the various devices should not be used interchangeably in following up a given patient. Intriguingly, M-OCT had less systematic error than A-OCT, an important outcome that clinicians should consider when deciding to use an OCT device. [ABSTRACT FROM AUTHOR]

PURPOSE: The objective of this study was to assess the concordance between the values obtained in measuring central corneal thickness using the OrbscanIIz® and the contact ultrasonic pachymeter available in our public ophthalmology service. METHODS: Measurements were taken from 88 eyes of 44 patients using the two instruments. The data obtained were statistically analyzed using version 22 of the IBM SPSS® program. RESULTS: The mean of central corneal thickness measurements obtained from OrbscanIIz® was significantly higher than that obtained from ultrasound pachymetry. However, the mean of differences between both instruments was only 7.22 µ, which could be considered a clinically insignificant result when considering the good concordance obtained between both systems. CONCLUSION: OrbscanIIz® and ultrasound pachymetry can be interchangeable in the usual public clinical practice when measuring central corneal thickness. This is the first research found in the literature that uses a concordance study to compare the data resulting from central corneal thickness measurements obtained by an OrbscanIIz® and an OcuScan® pachymeter in our environment. [ABSTRACT FROM AUTHOR]

PURPOSE: The purpose of this study was to compare ultrasound pachymetry Ultrasound pachymetry (UP), specular microscopy (SM), and anterior segment optical coherence tomography (ASOCT) in the measurement of central corneal thickness (CCT) in cases of corneal edema before and after uncomplicated phacoemulsification. METHODS: Preoperative pachymetric measurements were performed in all patients before cataract surgery. Sixty -seven patients who developed corneal edema after routine faoemulsification surgery were included in the study. CCT measurements were made the day before surgery and on the 1st, 7th, and 14th days after surgery. Correlation and agreement between the devices were quantified with the intraclass correlation coefficient (ICC), limits of agreement, and Bland--Altman plots. RESULTS: The mean age of the patients was 70.99 ± 9.56 (36-92) years. While CCT could be measured in all eyes with ASOCT after surgery, the number of eyes measured with UP and SM were 24 (11.7%) and 27 (16.1%), 55 (82.1%) and 52 (77.6%), and 46 (88.8%) and 45 (86.9%) on postoperative days 1, 7, and 14, respectively. ICC values between UP and SM, UP and ASOCT, and SM and ASOCT, respectively, were: preoperative 0.91, 0.94, and 0.92; 1st postoperative day 0.93, 0.86, and 0.93; 7th postoperative day 0.94, 0.85, and 0.96; and 14th postoperative day 0.95, 0.92, and 0.96. CONCLUSION: In all eyes with corneal edema, CCT measurements can be taken with ASOCT; however, in some cases, CCT measurements with SM and UP cannot be taken. However, there is a good correlation between measurements taken with these devices. [ABSTRACT FROM AUTHOR]

This study aimed to analyze the central corneal thickness (CCT) in diabetic patients with and without diabetic retinopathy (DR) by investigating the impacts of other CCT factors such as hemoglobin A1c (HbA1c) levels, diabetes mellitus (DM) duration, and the DR stages. The study also compared the results of two measuring devices – anterior segment-optical coherence tomography (AS-OCT) and ultrasound pachymetry (UP). However, the existing research possesses bias in revealing the precise measurement of CCT. The study enrolled 300 participants who were segregated into three equal groups: group A with DR, group B without DR, and the control group. The study tested the following formulated hypothesis, like the correlation between the age, duration, and HbA1c level of diabetic patients with DR and without DR. The effectiveness of the AS-OCT and UP was assessed through statistical analysis. The experiment revealed a considerable statistical difference in the formulated hypothesis and observed that AS-OCT had higher efficacy than UP in estimating CCT in all the groups. The study recommends the prompt utilization of devices such as AS-OCT to precisely predict CCT. This could greatly benefit DM patients with retinopathy conditions for better decision-making and reliable measures during glaucoma surgery. [ABSTRACT FROM AUTHOR]

PurposeTo assess the relationship between corneal thinning measured by clinician-graded slit-lamp examination compared with ultrasound pachymetry (USP), anterior segment optical coherence tomography (AS-OCT), and the Pentacam.MethodsPatients with corneal thinning underwent USP, AS-OCT, Pentacam measurements and standardized clinical grading by 2 cornea specialists estimating thinning on slit-lamp examination. Reproducibility of each testing modality was assessed using the intraclass correlation coefficient. Bland-Altman plots were used to determine precision and limits of agreement (LOA) between imaging modalities and clinical grading.ResultsWe included 22 patients with corneal thinning secondary to infectious or inflammatory keratitis. Mean percent stromal thinning estimated by grader 1 was 51% (SD 31) and grader 2 was 49% (SD 33). The intraclass correlation coefficient between the masked examiners was 0.95 (95% confidence interval, 0.88-0.98). Graders were more similar to each other than to any other modality with 2% difference and 4.6% of measurements outside the LOA. When measuring the area of maximum thinning, AS-OCT measured approximately 10% thicker than human graders while the Pentacam measured approximately 10% thinner than human graders with 16.7% outside the LOA. USP measured approximately 20% thinner than human graders with 5.6% outside the LOA.ConclusionsTrained corneal specialists have a high degree of agreement in location and degree of corneal thinning when measured in a standardized fashion on the same day. Other testing modalities had acceptable reproducibility and agreement with clinical examination and each other, although Scheimpflug imaging fared worse for corneal thinning, particularly in the periphery, than the other modalities.

Abstract Background To compare the difference in central corneal thickness (CCT) measurements in normal eyes between a rotating Scheimpflug camera combined with a Placido-disk corneal topographer (Sirius, CSO, Italy) and ultrasound pachymetry (USP). Methods A systematic literature search was conducted for relevant studies published on PubMed, Medline, EMBASE, and the Cochrane Library and ClinicalTrials.gov from inception to August 1st, 2019. Primary outcome measures were CCT measurements between Sirius and USP. A random effects model was used to pool CCT measurements. Results A total of twelve studies involving 862 eyes were included in this meta-analysis. The meta-analysis found CCT measurements between Sirius and USP to be statistically significantly different (P

Purpose: To compare the central corneal thickness (CCT) measured by non-contact tono-pachymeter [Tonopachy (TP)] with the gold standard ultrasound pachymetry (UP) in normal children and in children with refractive error. Methods: This cross-sectional study involved 95 normal children (190 eyes) and 123 children with refractive error (246 eyes), a total of 218 children (436 eyes) aged 7-15 years. After refraction and complete ophthalmic evaluation, axial length was measured with IOLMaster 700, CCT was measured with TP followed by UP. The correlation between the CCT measurements obtained with the two methods was analysed by Intraclass correlation coefficient (ICC) and the limits of agreement were assessed with Bland-Altman analysis plot. Results: Mean CCT measured with TP was 537.46 ± 36.41 μm and by UP was 537.17 ± 39.80 μm in normal children (P = 0.79) and in refractive error group, the mean CCT was 533.50 ± 34.91 μm by TP and 531.60 ± 36.30 μm by UP (P = 0.04). The 95% limits of agreement between TP and UP ranged from -19.2 to + 21.6 μm (mean = 1.20) for total children, -20.8 to + 21.4 μm (mean = 0.29) for normal group and -18.0 to + 21.8 μm (mean = 1.90) for refractive error group. ICC for CCT measurement between TP and UP was 0.980 for total children and refractive error group and 0.981 for normal group. Conclusion: The CCT measurement obtained by TP showed an excellent agreement with UP. Hence non-contact TP can be used to assess CCT in children above seven years of age.

ObjectiveTo obtain normative data for the canine cornea and conjunctiva using high-resolution time- and Fourier-domain optical coherence tomography (TD-OCT and FD-OCT) and ultrasound pachymetry (USP).AnimalsOne hundred sixty-eight eyes of 133 healthy young intact laboratory beagles.ProceduresThe cornea and conjunctiva of 16 eyes of 8 healthy young intact female beagles were imaged using FD-OCT. Corneal thickness was measured with FD-OCT and USP, while corneal epithelial thickness and conjunctival epithelial thickness were measured with FD-OCT. The central corneal thickness (CCT) was determined in 152 eyes of 125 healthy young adult intact female (35) and male (90) beagles using TD-OCT. Mixed effects linear regression was used for statistical analysis.ResultsThe CCT was (mean ± standard deviation) 497.54 ± 29.76, 555.49 ± 17.19, and 594.81 ± 33.02 μm as measured by FD-OCT, USP, and TD-OCT, respectively. The central, superior paraxial, superior perilimbal corneal epithelial thickness and superior bulbar conjunctival epithelial thickness were 52.38 ± 7.27, 56.96 ± 6.47, 69.06 ± 8.84 and 42.98 ± 6.17 μm, respectively. When comparing techniques used for measuring CCT (USP vs. FD-OCT and FD-OCT vs. TD-OCT), USP and TD-OCT generated significantly greater values in comparison with FD-OCT (both P

Background: Central Corneal Thickness (CCT) measurement is useful in the management of glaucoma, ocular hypertension, corneal lesions and kerato-refractive surgeries. The study aims to compare the CCT measurements between Ultrasound Sonography (USS) and Optical Coherence Tomography (OCT), to analyze correlation and agreement between these instruments as well as repeatability of each instrument. Methodology: A cross sectional comparative study carried in 100 eyes of 50 patients attending Rachel Eye Center in Abuja from January to March 2021. The CCT were taken using the USS and OCT. CCT was measured using the Pachscan ultrasound and the Optovue machine utilised for the OCT technique. Data was analysed using SPSS version 20 using Paired Sample t Test, Pearson's correlation, Interclass Correlation and Bland Altman Methods. Results: Patients were aged between 18 and 79 (mean age of 39.1), 72 males and 28 females. The mean CCT was 537.36 ±33.26 and 510.94 ±33.13 for USS and OCT respectively with a mean difference of (26.42±9.53 p<0.001). There was a very strong correlation of the 2 sets of measurement r = 0.997 p<0.001. There was a high average mean intraclass correlation coefficient of 0.843 between the two instruments and this was excellent (0.961) within the 95 percentile upper limit but poor in the (0.096) lower limit. There was a high correlation and no statistical significant difference in the comparing repeated mean USS and OCT measurements. There was an excellent average mean Intraclass Correlation Coefficient of 0.999/0.997 for the repeated OCT and USS values and this was found to be excellent(0.999/0.998) within the 95 percentile upper limit and (0.997/0.994)lower limit respectively. Conclusion: We find that measurements of CCT using the Pachscan ultrasound and the Optovue OCT correlate well, but the mean Pachscan measures were significantly higher than Optovue measures. [ABSTRACT FROM AUTHOR]

Objectives: Investigation of the compatibility between central corneal thickness (CCT) measurements in healthy eyes by comparing standard ultrasound pachymetry (USP) with noncontact tono-pachymetry (NCT) and specular microscopy (SM) devices was aimed. Methods: Forty-five eyes of 45 healthy volunteers aged between 18 and 60 years were included in this study. CCT of all cases was evaluated with USP, NCT, and SM devices. The same examiner performed all examinations. Bland-Altman plots and intraclass correlation coefficients were used to evaluate the agreement between instruments. Results: The mean age of the patients was 31±10.2 years. Fifteen (33.3%) cases were male and 30 (66.7%) were female. The mean CCT measured using NCT (559.3±39 µm) was significantly higher than those measured using SM (534.8±41 µm) and USP (542.6±43 µm, p<0.001). Bland-Altman analysis showed that the difference between the first, second, and third measurements was evenly dispersed around the mean, with no clear trend toward over- or underestimation by either NCT, USP, or SM. The 95% limits of agreements were 0.30-48.72 µm for NCT, -12.63-46.04 µm for the USP, and -24.41-8.80 µm for the SM. Correlation analysis between the three devices showed a very strong positive correlation (p<0.001). Conclusion: Significant differences were observed between CCT measurements in healthy individuals used in ophthalmology practice and performed with different devices. This situation should draw attention to the fact that in diseases such as glaucoma and endothelial insufficiency, corneal thickness monitoring should be done with the same device and the devices should not be used interchangeably. [ABSTRACT FROM AUTHOR]

Aims: Evidence for choosing a satisfactory device for central corneal thickness (CCT) measurement in children particularly pseudophakic and aphakic ones is insufficient. The aim of this study is to compare four differently measured CCTs obtained using ultrasound pachymetry (UP), Pentacam, partial coherence interferometry (PCI), and specular microscopy (SM) in phakic, pseudophakic, and aphakic children and assess the agreement between the six pairs of the methods. Methods: Children with history of cataract surgery at age six or younger and phakic children were recruited into this study. CCT was measured using UP (Optikon 2000, Rome, Italy), Pentacam (Oculus Inc, Wetzlar, Germany), PCI (IOLMaster 700, Carl Zeiss Meditec AG, Jena, Germany), and SM (Topcon SP-3000P; Topcon Corporation, Japan). Results: One-hundred two eyes (53 phakic, 29 pseudophakic, and 20 aphakic eyes) were included. The mean ages (± SD) of phakic, pseudophakic, and aphakic cases were 9.75 (± 3.3), 9.9 (± 2.3), and 8.2 (± 2.8) years, respectively. The mean CCTs (± SE) for phakic children using Pentacam, PCI, UP, and SM were 549.7 (± 5.0), 546.5 (± 4.5), 565.9 (± 5.5), and 506.2 (± 4.4) μm, respectively, for pseudophakic cases were 570.1 (± 6.4), 565.0 (± 6.1), 571.9 (± 6.3), and 524.3 (± 6.3) μm, respectively, and for aphakic participants were 635.3 (± 14.2), 635.4 (± 14.5), 649.0 (± 13.5), and 589.1 (± 13.3) μm, respectively. Conclusion: Compared to Pentacam and PCI, SM underestimated CCT particularly in phakic and pseudophakic children, whereas UP slightly overestimated CCT especially in phakic and aphakic children. Furthermore, Pentacam and PCI had the closest agreement. By contrast, SM had the poorest agreement with the other three methods. [ABSTRACT FROM AUTHOR]

Purpose: To determine the mean difference in central corneal thickness between ultrasound pachymetry and anterior segment optical coherence tomography in patients visiting tertiary care hospital of Karachi. Study Design: Cross sectional study. Place and Duration of Study: Department of Ophthalmology, Liaquat National Hospital, Karachi from 27th December 2018 to 26th June 2019. Methods: Total 216 eyes of 108 patients were divided into two groups. Central corneal thickness was measured using ultrasound pachymeters in group A and with anterior segment optical coherence tomography in group B. Data was collected and analyzed using SPSS version 21. Mean central corneal thickness was compared between the two methods. Stratification was done on gender, age and post-stratification independent sample t-test was applied for mean difference CCT and P-value ≤ 0.05 was taken as significant. Results: Total 108 patients were equally divided into two groups. Mean age was 48.70 ± 7.82 years in group A and 50.66 ± 6.88 years in group B. In group A, there were 74.1% males and 25.9% females while in group B, there were 75.9% males and 24.1% females. There was statistically significant difference between the mean central corneal thickness of group A and group B for right and left eyes (p < 0.001). Mean difference was also compared for gender and age groups. We found statistically significant differences in central corneal thickness in between the two methods in both age groups (≤45 years and > 45 years). Conclusion: Central corneal thickness was more with pachymeters as compared to the AS-OCT (p value < 0.05). [ABSTRACT FROM AUTHOR]

Purpose: To compare the central corneal thickness (CCT) measured by non-contact tono-pachymeter [Tonopachy (TP)] with the gold standard ultrasound pachymetry (UP) in normal children and in children with refractive error.Methods: This cross-sectional study involved 95 normal children (190 eyes) and 123 children with refractive error (246 eyes), a total of 218 children (436 eyes) aged 7-15 years. After refraction and complete ophthalmic evaluation, axial length was measured with IOLMaster 700, CCT was measured with TP followed by UP. The correlation between the CCT measurements obtained with the two methods was analysed by Intraclass correlation coefficient (ICC) and the limits of agreement were assessed with Bland-Altman analysis plot.Results: Mean CCT measured with TP was 537.46 ± 36.41 μm and by UP was 537.17 ± 39.80 μm in normal children (P = 0.79) and in refractive error group, the mean CCT was 533.50 ± 34.91 μm by TP and 531.60 ± 36.30 μm by UP (P = 0.04). The 95% limits of agreement between TP and UP ranged from -19.2 to + 21.6 μm (mean = 1.20) for total children, -20.8 to + 21.4 μm (mean = 0.29) for normal group and -18.0 to + 21.8 μm (mean = 1.90) for refractive error group. ICC for CCT measurement between TP and UP was 0.980 for total children and refractive error group and 0.981 for normal group.Conclusion: The CCT measurement obtained by TP showed an excellent agreement with UP. Hence non-contact TP can be used to assess CCT in children above seven years of age. [ABSTRACT FROM AUTHOR]

Background To determine the difference between corrected intraocular pressure (IOP), based on the central corneal thickness (CCT), measured by the noncontact anterior segment anterior segment optical coherence tomography (AS-OCT), versus contact ultrasound pachymetry (USP) in the management of glaucoma patients. Patients and methods Ophthalmology Department, Ain Shams University, Cairo, Egypt. The study is a prospective, nonrandomized case series. Fifty patients were diagnosed with open-angle glaucoma and controlled with medical treatment with prostaglandin analogs and β-blockers fixed combination, controlled under medical treatment. CCT is measured by two methods, the AS-OCT and by the USP of ocular response analyzer. IOP was measured by applanation tonometry. Corrected IOP was calculated adjustment factor using Ehler’s correction nomogram, statistical analysis of the adjusted IOP with the contact and noncontact methods was done in relation to the CCT measurements. Results The mean age was 60.5±5.24 years, 54% of the studied patients were men while 46% were women. The mean CCT using AS-OCT for the right eye was 529.86±43.52 μm and for the left eye was 530.28±43.57 μm, while CCT using USP for the right eye was 534.88±43.59 μm and for the left eye was 533.34±44.33 μm. Highly significant correlation between CCT was measured by AS-OCT and ultrasound; 0.94 (P

Purpose: To assess the agreement between Orbscan 3, Pentacam HR and ultrasound pachymetry (Palm Scan AP 2000) in measuring central corneal thickness. Methods: Prospective observational cross-sectional study of ninety-two eyes of 48 patients with normal corneas was conducted. Central corneal thickness was measured via Pentacam HR, Orbscan 3 and ultrasound pachymetry. Bland–Altman analysis was used to demonstrate agreement between various methods. Results: Ninety-two eyes of 46 subjects were enrolled. The mean age was 29.67 years (18–59). The average measurements of central corneal thickness were 545.73 ± 29.35 μm, 549.34 ± 29.14 μm and 545.78 ± 31.48 μm for the Pentacam HR, Orbscan and ultrasound pachymetry, respectively. The three devices measurements are closely correlated, with Pearson correlation coefficient ranging from 0.868 to 0.929. The 95 % limits of agreement were 25.2 to − 18 μm between Orbscan and Pentacam central corneal thickness, 25.2 to − 25.7 μm between Pentacam and pachymetry central corneal thickness and 34.4 to − 27.2 μm between Orbscan and pachymetry central corneal thickness. Conclusion: In spite of advancement of Orbscan 3, still there are wide agreement limits between CCT measurements obtained via Orbscan 3, Pentacam HR and ultrasound pachymetry; thus, interchangeable use in clinical practice is not recommended. [ABSTRACT FROM AUTHOR]

Purpose: To determine the mean difference of central corneal thickness measurements by using ultrasound Pachymetry and oculus Wave light Occulyzer II. Study Design: Cross-sectional comparative study using non-probability consecutive sampling. Place and Duration of Study: This study was conducted at Department of Ophthalmology, Liaquat National Hospital Karachi from November 2018 to June 2019. Material & Methods: After approval from ethical committee, patients were included in our study on the basis of inclusion & exclusion criteria. Central corneal thickness measurements were taken by using ultrasound Pachymetry & oculus Wave light Occulyzer II. All the data was collected by single researcher. The results were plotted, compared & analyzed. Paired t-test was used for the comparison of quantitative variables. Results: There were 130 patients included in the study out of which 73 (56.2%) were males and 57 (43.8%) were females. Mean age of these patients was 33.9 ± 8.9 years. The mean ± SD thinnest oculus Wave light Occulyzer II measurement was 538.61 ± 23.46 µm and ranged between 476.0 and 619.0 µm whereas the mean thinnest ultrasound Pachymetry measurement was 535.1 ± 21.816 µm and ranged between 482 and 601 µm. There was highly significant correlation of central corneal thickness between both the instruments. (r = 0.96, p < 0.001). Conclusion: There is a high correlation of central corneal thickness between the readings obtained from ultrasound and optical pachymetry machines therefore oculus Wave light Occulyzer II can be used as an alternative technique to ultrasound pachymetry while assessing CCT in clinical settings. [ABSTRACT FROM AUTHOR]

Background To determine the difference between corrected intraocular pressure (IOP), based on the central corneal thickness (CCT), measured by the noncontact anterior segment anterior segment optical coherence tomography (AS-OCT), versus contact ultrasound pachymetry (USP) in the management of glaucoma patients. Patients and methods Ophthalmology Department, Ain Shams University, Cairo, Egypt. The study is a prospective, nonrandomized case series. Fifty patients were diagnosed with open-angle glaucoma and controlled with medical treatment with prostaglandin analogs and β-blockers fixed combination, controlled under medical treatment. CCT is measured by two methods, the AS-OCT and by the USP of ocular response analyzer. IOP was measured by applanation tonometry. Corrected IOP was calculated adjustment factor using Ehler's correction nomogram, statistical analysis of the adjusted IOP with the contact and noncontact methods was done in relation to the CCT measurements. Results The mean age was 60.5±5.24 years, 54% of the studied patients were men while 46% were women. The mean CCT using AS-OCT for the right eye was 529.86±43.52 μm and for the left eye was 530.28±43.57 μm, while CCT using USP for the right eye was 534.88±43.59 μm and for the left eye was 533.34±44.33 μm. Highly significant correlation between CCT was measured by AS-OCT and ultrasound; 0.94 (P<0.01). Mean adjusted IOP by AS-OCT CCT was 15.56±2.83 mmHg (11–22) and IOP adjusted by USP was 15.32±2.78 mmHg (10–21), with no significant differences (P=0.29) and highly significant correlation; 0.96 (P<0.01). Conclusion Although USP has slightly higher measurements of CCT in comparison with measurements with anterior segment OCT, it has no significance on the adjusted IOP in controlled glaucoma patients, making the two methods equally accurate in the management and follow-up of these patients. [ABSTRACT FROM AUTHOR]

Background: To compare the consistency between the average scores of the contact central corneal thickness measurements from ultrasound pachymetry devices still gold standard, such as iPac® and Echoscan US-500, and noncontact measurements via Pentacam HR and Sirius topography.Methods: This prospective study, subsequently admitted to the ophthalmology department, 76 healthy individuals were performed. The measurements were repeated three times for each eye, and average scores were statistically analyzed on the same day and almost at the same time. While measuring the eyes, Pentacam HR, Sirius topography, iPac®, and Echoscan US-500 were used, respectively. The inter-rater agreement of measurements from the devices was assessed with intraclass correlation coefficient, and 95% Confidence Interval and p values demonstrating statistically significance were also presented. In the graphical assessment of the agreement, the Bland-Altman graph was used.Results: Among 76 study participants, 43 (56.6%) were composed of women, and age level was 38.6 ± 12.5 years, ranging between 18 and 69. It was observed that the highest agreement was between the measurements obtained from Echoscan US-500 and iPac® devices, but the agreement between the measurements of different devices was higher than 0.90. Bland-Altman graphics were also investigated; the results of four different devices were seen to be consistent with one another.Conclusions: Therefore, the devices we compared in the study can be used as alternatives to one another due to the higher consistency between CCT measurements provided with through UP devices of Echoscan US-500 and iPac®, and Pentacam HR and Sirius topography devices.Clinical Trial Registration number: 2016/112 [ABSTRACT FROM AUTHOR]

AIM: To compare the central corneal thickness(CCT), keratometry(K)reading, anterior chamber depth(ACD), and axial length(AL)measured with Lenstar and Pentacam with those obtained with the ultrasound(US)pachymetry in the cataract patients.METHODS: A total of 158 eyes of 158 patients were examined in this study. The CCT, average K, ACD and AL obtained by Lenstar and/or Pentacam were compared with those obtained from US pachymetry using repeated-measures analysis of variance, Pearson correlation coefficients and Bland-Altman analyses.RESULTS: The mean CCT obtained using Lenstar and Pentacam were 536.54±27.90μm and 541.46±29.85μm(t=-5.439; Pt=-0.348, P>0.05). The mean ACD measured using the Pentacam, Lenstar, and US pachymetry were 2.73±0.38mm, 2.71±0.38mm, and 2.85±0.40 mm, respectively(F=309.94, Pr=0.989, 0.978, and 0.977; Pt=-19.482, Pr=0.996; PCONCLUSION: Although there were statistically significant differences, the measurements obtained by the Lenstar and the Pentacam were highly repeatable and the instruments easy to use.

AIM: To investigate and compare anterior chamber depths(ACDs)measured using the Pentacam, the IOLMaster, and ultrasound pachymetry(US).METHODS: The present study was observational in nature. ACDs were measured in 138 eyes of 69 myopic patients, by the same operator, using the Pentacam, the IOLMaster, and US. We assessed the agreement among the three methods using Bland-Altman plots. The repeatability among the three methods was evaluated by within-subject standard deviation. RESULTS: The means±SDs of ACDs measured using the Pentacam, the IOLMaster, and US were 3.77±0.24, 3.73±0.23, and 3.69±0.22mm respectively. Bland-Altman analysis showed that Pentacam and IOLMaster data were in good agreement(CoA, 0.04mm; LoA,0.05 to 0.13mm), as were US and IOLMaster data(CoA, 0.04mm; LoA, 0.17 to 0.08mm), but the Pentacam ACD values were slightly greater than the US figures(CoA, 0.08mm; LoA, 0.06 to 0.22mm). Measurements of the ACD with the three devices also showed high repeatability(Sw=0.03, 0.02, and 0.03; 2.77 Sw=0.08, 0.06, and 0.08, respectively). The three depth estimates were positively correlated(r=0.946, 0.987, and 0.951; PCONCLUSION: Measurement of ACDs using the Pentacam, the IOLMaster, and US showed good agreement and repeatability. The Pentacam and IOLMaster ACDs, and the IOLMaster and US ACDs, agreed reasonably well, but agreement between the Pentacam and US data was poorer. However, both the absolute differences and the coefficients of variation were small, and the observed variability was likely not clinically significant.

Purpose: To compare and determine the repeatability of central corneal thickness (CCT) measurements using four noncontact pachymetry instruments in eyes with keratoconus. Materials and Methods: The CCT of consecutive patients with keratoconus was measured during a single visit using the swept source optical coherence tomography (SS-OCT, Casia SS-1000°CT, Tomey, Nagoya, Japan), a rotating Scheimpflug camera system (Pentacam, Oculus Optikgerate GmbH, Wetzlar, Germany), scanning slit topographer (Orbscan IIz topography, Baush and Lomb Surgical Inc., San Dimas, CA, USA), and a hand-held spectral domain OCT (HHSD-OCT, Bioptigen Inc., Durham, North Carolina, USA). Test-retest variability, correlation between measurements and interdevice agreement were analyzed. Results: Fifty eyes of 25 participants were analyzed in this study. All measurement methods correlated well with each other (r > 0.9, P < 0.001). Mean ± standard deviation CCT measured by HHSD-OCT, Orbscan IIz, SS-OCT, and Pentacam was 462 ± 41 mm, 458 ± 41 mm, 454 ± 40 mm, and 447 ± 42 mm, respectively. While the HHSD-OCT over-estimated the CCT (P < 0.001), there was a good correlation between the measurements obtained from the other three devices. However, the numerical difference was high and this trend was seen in all the paired comparisons.Conclusions: Though the measurements by different devices correlated well, the numerical agreement may be inadequate for their interchangeable use in clinical practice.

Purpose: To compare ultrasound pachymetry and Orbscan II for measurement of central corneal thickness (CCT) in normal eyes. Methods: The current study was performed at Labbafinejad Medical Center (LMC), Tehran, Iran. Three hundred eyes from 150 healthy individuals referred for keratorefractive surgery were assessed first by Orbscan II and then by ultrasound pachymetry, and CCT values were recorded and compared. Results: Overall, Orbscan II overestimated CCT as compared to ultrasound pachymetry by about 2.4% (mean values 547.6 ± 34.7 versus 534.8 ± 34.7, respectively, P < 0.001). The difference was more significant when CCT was less than 500 microns (mean values 493.2 ± 16.9 versus 479.9 ± 15.6, mean overestimation: 2.6%, P < 0.001). There was good linear correlation between the two methods (Pearson′s correlation r = 0.968, P < 0.0001). Conclusion: Orbscan II has good correlation with ultrasound pachymetry for measurement of CCT in normal eyes; however Orbscan II should not be used to evaluate corneal thickness before keratorefractive surgeries, as it tends to overestimate corneal thickness and may result in undesirable, low residual stromal thickness.

Background: Corneal thickness (CT) is an important parameter in refractive surgery but available data is scanty on corneal thickness of normal Malays. The purpose of this study is to determine central and peripheral CT in a sample of Malays and find its effect on age. Methods: Seventy-two (72) participants were invited to participate in this study. Their age ranged from 15 to 65 years old. CT was measured using an ultrasonic pachometer (Corneo-Gage TM Plus2) at 5 different locations namely central, superior, temporal, inferior and nasal regions of the cornea. A total of three readings were taken for each location of the cornea and the mean was calculated. CT was presented as total, epithelial and stromal thickness for three age groups, namely <20years, 21-40years and >40 years for comparison. Results: Mean value for central CT for Malays was 597.9 ± 35.2 µm and peripheral CT was significantly thicker than the centre at all locations. There was significant thinning in CT as age advanced at all locations except at the centre. The epithelial layers do not show any changes with respect to location and age which implied that changes in CT at different location and as results of advancing age were mainly due to the stroma. Conclusion: The values of CT in normal Malays was 597.9 ± 35.2 µm and CT was thinnest at the central region. Except at the central region CT decreased with advancing age. These values can be a suitable reference when planning for refractive surgery and penetrating keratoplasty among Malays. [ABSTRACT FROM AUTHOR]

Abstract: Objective: To evaluate the clinical efficacy among ultrasound pachymetry (UP), ultrasound biomicroscopy (UBM), and manual measurement (MM) with digital caliper by comparing corneal thickness (COT) values obtained from frozen canine corneas ex vivo. Procedures: COT was measured using UP, UBM, and MM in eight enucleated normal canine eyes frozen at −20 °C for 4 weeks. After thawing at room temperature for 2 h, the COT values were obtained from five sites on each cornea: central corneal thickness (CCOT), thickness at the 3, 6, 9, and 12 o'clock positions (3COT, 6COT, 9COT, and 12COT, respectively). For each device, measurements were performed three times at each designated site by one operator. Intraclass correlation coefficient, repeated‐measures analysis of variance, and Bland–Altman plot were performed for statistical analyses. Results: The mean CCOT was 839.0 ± 138.2, 857.6 ± 127.9, and 849.1 ± 132.8 μm for UP, UBM, and MM, respectively. There was no statistically significant difference among the measurements by all three devices (P > 0.05). The statistical agreement among these devices was also shown to be good according to Bland–Altman plots. In addition, the values measured on the peripheral sites of the cornea (3COT, 6COT, 9COT, and 12COT) also revealed no significant differences among the three devices. The difference between CCOT and peripheral corneal thickness was also statistically insignificant. Conclusions: The UP, UBM, and MM measurements showed statistically similar COT values. The UBM and UP provided accurate and reliable measurements comparable to MM and could be used effectively for clinical COT measurements. [ABSTRACT FROM AUTHOR]

Purpose: To compare central corneal thickness (CCT) measured by standard ultrasound pachymetry (USP), and three non-contact devices in healthy eyes. Methods: A cross-sectional study of CCT measurement in 52 eyes of 52 healthy volunteers was done by a single examiner at Ocular Surface and Contact Lens Laboratory. Three consecutive measurements were done by standard USP, non-contact tono-pachymeter, Pentacam corneal topographer, and Anterior Segment Optical Coherence Tomography (AS-OCT). The mean values were used for assessment. The results were compared using multivariate ANOVA, linear regression, and Pearson correlation. Agreement among the devices was analyzed using mean differences and Bland-Altman analysis with 95% limits of agreement (LoA). Finally, reliability was analyzed using intraclass correlation coefficient (ICC). Results: Mean CCT by ultrasound pachymeter, tono-pachymeter, corneal topographer and AS-OCT were 558.9 ± 31.2 µm, 525.8 ± 43.1 µm, 550.4 ± 30.5 µm, and 545.9 ± 30.5 µm respectively. There was a significant positive correlation between AS-OCT and USP (Pearson correlation = 0.957, p < 0.001), corneal topography and USP (Pearson correlation = 0.965, p < 0.001), and corneal topography and AS-OCT (Pearson correlation = 0.965, p < 0.001). There was a lower correlation between CT-1P tono-pachymeter and the other three modalities. Intraclass correlation coefficients show an excellent reliability between pairs except for CT-1P against the other three instruments that were found moderate. Conclusions: CT-1P tono-pachymeter underestimates CCT measurements compared to Scheimpflug system, AS-OCT device, and USP. Mean CCT among USP, Pentacam and AS-OCT were comparable and had significant linear correlations. In clinical practice, these three modalities could be interchangeable in healthy patients. [ABSTRACT FROM AUTHOR]

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This study was conducted to analyze the profile and thickness of endothelial keratoplasty lenticules prepared from fresh donated whole eyes with Visante optical coherence tomography (V-OCT) compared to measurements obtained from ultrasound pachymetry (USP) at the Central Eye Bank of Iran. Microkeratome-assisted precut corneas were prepared for Descemet stripping automated endothelial keratoplasty by using standard eye bank protocol. Central posterior lenticule thickness (CPLT) on fresh whole eye, before excising corneoscleral disc and transferring to Optisol-GS, was measured by USP. V-OCT was used to measure central, paracentral, and midperipheral thicknesses of lenticules after transferring the tissue to Optisol-GS. Chi Square and Bonferroni tests were respectively used to uncover the differences between the USP and V-OCT measurements and also the thickness profile of lenticules. Postoperative reports for the entire transplanted lenticules were recorded. Accordingly, on evaluation of 312 enrolled precut corneas, CPLT measurements by V-OCT versus USP were statistically different (mean: 136 µm vs 165 µm, respectively; P = 0.008). Thickness profile of the posterior lenticules revealed increased thickness from the central to the peripheral parts of the cornea (mean increase of 16 µm at the pericentral and 64.2 µm at the peripheral locations, respectively); however, the increase in the thickness was relatively symmetrical. Postoperative reports of transplanted lenticules were unremarkable, since there were no posterior flap detachments. In essence, V-OCT measurements of microkeratome-assisted precut lenticules prepared from fresh donated whole eyes averaged 29 μm thinner than USP measurements and revealed a significant but symmetric increase of thickness towards the peripheral parts of the corneas. However, the variation in the thickness profile did not affect the attachment or the clarity of transplanted precut lenticlues. [ABSTRACT FROM AUTHOR]

Pur po se: To evaluate the changes in central corneal thickness (CCT) in patients with different values before cataract surgery. Ma te ri al and Met hod: 90 eyes of 70 patients who had undergone uneventful cataract surgery because of senile cataract were included in this prospective study. The CCT was measured by ultrasound pachymetry. The patients were evaluated in 4 groups according to preoperative CCT values (group 1: 450-500 μm, group 2: 501-550μm, group 3: 551-600μm, and group 4: 601-650μm). The CCT was measured preoperatively and at 1st, 2nd, 4th, and 8th weeks postoperatively. The chi-square test and one-way analysis of variance test were used for statistical analysis. Re sults: The increase in CCT was highest in group 1 determined as 71.3 μm. The increase in group 2 was 43.4, 35.1 in group 3, and 16.6 μm in group 4. The increase in CCT was significant in all groups at week 1 ( p

Purpose: The aim of this study was to provide average values for central corneal thickness (CCT) and corneal curvature (CC) and also to determine a regression model for the relationship between CCT and CC in adult Nigerians without glaucoma. Methods: A total of 95 subjects consisting of 56 males and 39 females aged between 20 and 69 years with mean age of 47.1 ± 14.1 years were recruited for the study. Central corneal thickness was measured by ultrasound pachymetry (SW-1000P ultrasound pachymeter, Tianjin Suowei Electronic Technology, China) and corneal curvature was measured by keratometry (Bausch & Lomb keratometer H-135A, USA). Results: The average values of 550.1 ± 33.1µm and 43.0 ± 1.1 D were obtained for CCT and CC respectively. CCT significantly correlated with age (p=0.01), and the regression model predicts a decrease of 6.0 µm in CCT per decade. No significant association was found between CC and age (p=0.56). Also, no significant association was found between CCT and CC (p=0.07). Female subjects had significantly steeper corneas than their male counterparts. Conclusion: Central corneal thickness decreases with increasing age. Neither CCT nor age appear to be significantly correlated with corneal curvature. (S Afr Optom 2011 70(1) 44-50)

AIM: To compare the differences and the relationships of central corneal thickness(CCT)measurements among optical coherence tomography(OCT), Tomey pachymetry and ultrasound pachymetry after laser assisted subepithelial keratomileusis(LASEK). METHODS:Forty-nine patients(96 eyes)with myopia after 6mo of LASEK were assigned to measure the CCT by OCT, Tomey pachymetry and ultrasound pachymetry. Paired t-test and Pearson correlation analysis was used for statistical analysis. RESULTS: The mean CCT measured by OCT, Tomey pachymetry and ultrasound pachymetry was(475.15±33.67μm),(447.80±34.11μm),(465.18±34.23μm), respectively. Surgery reserved mean CCT was(431.22±35.32)μm. There were statistically differences between two comparative measured results(PPCONCLUSION: The CCT measurements of three instruments were not interchangeable.

Purpose: To compare corneal pachymetry assessment by the Galilei dual Scheimpflug analyzer with that done by ultrasound (US) pachymetry. Materials and Methods: Forty six patients (92 eyes) were subjected to corneal pachymetry assessment by Galilei dual Scheimpflug analyzer and US. All the readings were taken by a single operator. Intraoperator repeatability for the Galilei was assessed by taking 10 readings in one eye each of 10 patients. To study the interoperator reproducibility for the Galilei, two observers took a single reading in both the eyes of 25 patients. Results: The mean central corneal thickness (CCT) measured by US was 541.83 ± 30.56 μm standard deviation (SD) and that measured by Galilei was 541.27 ± 30.07 μm (SD). There was no statistically significant difference between both the methods (P < 0.001). The coefficient of repeatability was 0.43% while the coefficient of reproducibility was 0.377% for the Galilei. Conclusion: Objective, noncontact measurement of the CCT with the Galilei dual Scheimpflug analyzer was convenient, had excellent intraoperator repeatability and interoperator reproducibility, and findings were similar to those obtained with standard US pachymetry.