Mean Central Corneal Thickness Measurements Research Articles

Effects of fluorescein on corneal endothelial morphology after fundus fluorescein angiography in patients with diabetic macular edema

Purpose To evaluate the effects of fluorescein dye on corneal endothelial morphology (CEM) after fundus fluorescein angiography (FFA) in patients with diabetic macular edema (DME). Methods In this retrospective study, patients were divided into two groups, nonproliferative diabetic retinopathy (Group-1, NPDR) and proliferative diabetic retinopathy (Group-2, PDR). CEM properties including endothelial cell density (ECD), coefficient of variation of cell area (CV), average cell area (AVG), percentage of hexagonal cells (HEX), and central corneal thickness (CCT) were measured before FFA and at week 1 and month 1 after FFA were collected from patients’ charts. Results The study consisted of 48 patient’s 48 eyes in Group-1 and 50 patient’s 50 eyes in Group-2. In both groups, the mean ECD, CV, AVG, HEX, and CCT measurements at week 1 and month 1 after FFA did not differ statistically from the mean measurements before FFA (p > 0.05). The mean ECD measurements in Group-1 were higher than that in Group-2 and showed statistically significant differences among the groups (p < 0.01 for all). In the Pearson correlation analysis in Group-1, there was no statistically significant relationship between best-corrected visual acuity (BCVA) and (intraocular pressure) IOP values and ECD, AVG, CV, HEX, and CCT measurements (except central macular thickness [CMT] and HEX) before FFA, at week 1 and month 1 after FFA (p > 0.05). In Group-2 there was no statistically significant relationship between BCVA, IOP, and CMT measurements and ECD, AVG, CV, HEX, and CCT measurements before FFA, at week 1 and month 1 after FFA (p > 0.05). Conclusions There is no significant change in CEM after FFA in patients with NPDR and PDR with DME.

Comparison of Corneal Thickness Measurements After Customized Corneal Crosslinking Using High-Resolution Optical Coherence Tomography and Scheimpflug Tomography.

The aim of this study was to compare the evolution of corneal pachymetry after customized corneal crosslinking (CXL) between Scheimpflug-based and optical coherence-based corneal tomography (OCT). In this retrospective study, central corneal thickness (CCT), thinnest corneal thickness, and epithelial thickness of 33 eyes of 33 patients with keratoconus were measured preoperatively and 1, 3, and 12 months after customized CXL using the Pentacam HR and the MS-39. The mean pachymetry values of measurements were compared with a paired sample t test. Bland-Altman plots and 95% limits of agreement (LoA) were used to assess the agreement between the measurements of the 2 devices. The mean age of the participants was 29.7 ± 11.4 years. At baseline, the mean CCT measurements were equal with Pentacam HR (478.30 ± 36.77 μm) and MS-39 (478.46 ± 38.01 μm). After CXL, CCT obtained by Pentacam HR was 460.65 ± 38.69 μm, 464.65 ± 44.45 μm, and 476.77 ± 39.85 μm, and by MS-39 was 478.18 ± 39.50 μm, 472.89 ± 40.92 μm, and 479.51 ± 39.20 μm at 1, 3, and 12 months, respectively. Pentacam HR measured significantly lower CCT ( P < 0.05) at months 1 and 3 after CXL. The agreement was smallest between both devices at month 1 (95% LoA -59 to 24 μm) followed by month 3 (95% LoA: -41 to 23 μm). Epithelial thickness, measured with OCT alone, increased significantly at 1 month and regained preoperative levels at 3 months and thereafter. After CXL, corneal pachymetry significantly differs between OCT-based and Scheimpflug-based corneal tomography. Pentacam HR seems to underestimate pachymetry when haze is present.

Comparison of Central Corneal Thickness Measurement using Optical and Ultrasound Pachymetry in Primary Open Angle Glaucoma Patients

Introduction: A thinner Central Corneal Thickness (CCT) is an important criterion in determining the probability of progression from Ocular Hypertension (OHT) to Primary Open Angle Glaucoma (POAG). The most common devices for measuring CCT are ultrasound and optical pachymeters. Ultrasound pachymetry is a quick and precise approach to quantify corneal thickness that is also portable and inexpensive. The advantages of optical method include operator independency and noninvasiveness. Aim: To compare central corneal thickness using optical and ultrasound pachymetry in patients with POAG. Materials and Methods: This cross-sectional study was conducted at the Department Ophthalmology, ESI Post Graduate Institute of Medical Sciences and Research, Basaidarapur, Delhi, India, from October 2020 to April 2022. There were 105 POAG patients (210 eyes), divided into three subgroups of 35 subjects each (70 eyes each), based on the number of anti-glaucoma medications being instilled, topically (one/two/three drugs), and 35 healthy antiglaucoma controls (70 eyes). Central corneal thickness measurements were taken by Ultrasonic Pachymeter (USP) TOMEY SP-100, and by CEM-530 Non Contact Specular Microscope (NCSM) (optical). Statistical analysis was performed by the Statistical Package for Social Sciences (SPSS) program for Windows, version 17.0 (SPSS, Chicago, Illinois). Results: The mean CCT taken with NCSM and USP was 540.83±35.51 µm and 538.74±36.22 µm, respectively, in Right Eyes (RE) of 35 glaucoma patients on one drug, (p-value=0.80). Similarly, Left Eyes (LE), mean CCT with NCSM was 544.17±33.98 µm, and with USP was 541.69±36.6 µm (p-value=0.76). Mean CCT taken with NCSM and USP was 539.83±30,85 µm and 537.66±30.5 µm, respectively in RT eyes of 35 glaucoma patients on two drugs (p-value=0.76). Left eyes, mean CCT was 541.91±29.79 µm with NCSM as compared to USP which was 540.11±29.89 µm (p-value=0.80). On comparing the mean CCT values of RE in glaucoma subjects who were controlled on three antiglaucoma drugs it was found to be 528.37±26.44 µm using NCSM and 527.09±26.17 µm using USP (p-value=0.84). The meanvalues of CCT for LE was 521.94±26.53 µm with NCSM and with USP was 520±26.52 µm, respectively (p-value=0.81). Comparison of mean CCT measurements using NCSM and USP in 35 age-matched controls RE eye was found to be 517.83±21.27 µm and 515.97±20.91 µm, respectively (p-value=0.71). Similarly, for LE mean CCT values were 518.8±24.21 µm and 516.8±24.37 µm, respectively (p-value=0.73). Conclusion: The CCT measured using NCSM was found to be higher than that measured using USP in POAG subgroups patients as well as healthy age-matched controls, however the difference was not statistically significant. There was highly significant linear correlation between the CCT measured using NCSM and USP in all POAG subgroups as well as healthy controls. This suggests that the devices could be used interchangeably in glaucoma patients as well as healthy subjects of similar age group.

Agreement and Repeatability of Corneal Thickness and Radius among Three Different Corneal Measurement Devices.

Corneal refractive surgery screening, orthokeratology, and contact lens fitting require accurate estimation of the corneal thickness and curvature. We found that any of the imaging devices used in this study can be used to image a healthy myopic cornea, which is essential to screen for corneal ectasia. This study aimed to compare agreement and repeatability of corneal thickness and radius measurements obtained using Scheimpflug imaging (Pentacam HR), swept-source optical coherence tomography (Casia SS-1000), and Placido-Scheimpflug tomography (Topographic Modeling System, version 5 [TMS-5]). Sixty eyes of 60 subjects with myopia were measured with Casia, TMS-5, and Pentacam for their central corneal thickness (CCT), thinnest corneal thickness, central corneal radius of the steep meridian (Ks), central corneal radius of the flat meridian (Kf), mean central corneal radius (Km), and anterior and posterior best-fit spheres. Two readings were obtained from each instrument. Central corneal thickness was also measured with ultrasound pachymetry. Intraclass correlation coefficient, repeatability coefficient, and coefficient of variation were calculated. Repeatability coefficient, coefficient of variation, and intraclass correlation coefficient of CCT among the instruments ranged between 2.48 and 12.79, 0.17 and 0.86, and 0.98 and 1.00, respectively. Mean CCT measurements were similar between Casia, TMS-5, Pentacam, and ultrasound pachymetry (P = .13). Intraclass range of correlation for agreement was 0.95 to 0.99 for CCT among instruments. The range of 95% limits of agreement (LoAs) for ultrasound CCT was narrowest with Casia (31.94 μm). Casia-TMS-5 displayed a narrow range of 95% LoA for CCT (12.14 to -12.44), thinnest corneal thickness (12.31 to -11.31), and Ks (0.56 to -0.53), whereas Casia-Pentacam showed a narrow range of 95% LoA for Kf (0.56 to -0.42), Km (0.41 to -0.27), and anterior best-fit sphere (0.03 to -0.07). A significant difference in posterior best-fit sphere measurements was noted among all instruments (P = .01). Casia, TMS-5, and Pentacam can be used interchangeably to measure corneal thickness and radius measurement in healthy eyes. Casia had the best agreement with ultrasound pachymeter CCT and exhibited the highest repeatability.

Evaluation of tear function tests and corneal thickness in patients with meibomian gland dysfunction

Objectives: To investigate whether central corneal thickness (CCT) and tear function test differ from healthy controls in the ones suffering meibomian gland dysfunction (MGD). Methods: This prospective study was carried out with 99 individuals in total (50 patients MGD, 49 healthy individuals). Schirmer-1, tear break-up time (TBUT), the Ocular Surface Disease Index (OSDI) questionnaire and CCT measurmentwas administered to all patients.Results: The average Schirmer 1 measurements were 16.6 ± 3.3 mm for right eyes, 16.4 ± 3.6 mm for left eyes in the MGD group and 17.1 ± 3.7 mm for right eyes, 17.0 ± 4.4 mm for left eyes in the control group. The mean TBUT values were 10.1 ± 3.6 seconds for right eyes, 10.2 ± 3.4 seconds for left eyes in the MGD group and 14.7±3.7 seconds for right eyes, 15.8 ± 4.1 seconds for left eyes in the control group (p = 0.001). The mean OSDI score values were 40.3 ± 23.7 in the MGD group and 19.4 ± 8.7 in the control group (p = 0.001). The average CCT in the MGD group was 539.4 ± 30.0 µm and 539.7 ± 33.0 µm (right and left, respectively). The average CCT in the control group was 551.6 ± 32.8 µm and 550.7 ± 32.2 µm (right and left, respectively). The mean CCT measurements in the MGD group were not statistically significant compared to the healthy control group (p = 0.059, and p = 0.097, right and left, respectively). Conclusions: The Schirmer test and CCT measurements are not significantly different in patients with MGD compared to healthy control subjects.

English

BACKGROUND The main attributes of cornea which makes it optically important is its ability to maintain its dehydrated state. This corneal dehydration can be achieved and maintained by various factors among which corneal endothelial cell count and morphology play a significant role. Corneal attributes considered in this study i.e. the corneal endothelial cell count and central corneal thickness are extremely variable, and changes are seen even with smaller changes in anterior segment or overall structural changes in eyes. We wanted to compare central corneal thickness in emmetropia and axial myopia and compare corneal endothelial cell count in emmetropia and axial myopia. METHODS The sample size was decided taking into consideration various prevalence studies. The patients were consecutively recruited for the study considering the inclusion and exclusion criteria. The subjects were divided into two groups emmetropia and axial myopia and were differentiated on the basis of the axial lengths. Specular microscopy was performed for the subjects and corneal endothelial cell count, morphology and central corneal thickness were measured, and comparative study was performed. RESULTS This study of 80 eyes shows us that the difference between mean the corneal endothelial cell count between emmetrope (2812.80 cells / mm2) and axial myopes (2653 cells / mm2) is statistically significant where p was &lt; 0.05 while the mean central corneal thickness measurements didn’t show statistically significant change between emmetrope (490.05 microns) and axial myope. (489.37 microns). CONCLUSIONS Axial length has an indirect correlation with the corneal endothelial cell count which is statistically significant. While significant correlation between the central corneal thickness and axial length cannot be established in this study. KEY WORDS Emmetropia, Axial Myopia, Corneal Endothelial Cell Count, Central Corneal Thickness, Comparison

Agreement in central corneal thickness measurement between Corvis ST and ocular response analyzer.

To evaluate the agreement and interchangeability of noncontact devices of ocular response analyzer (ORA) and the Corvis ST in central corneal thickness measurement. In this prospective comparative study, central corneal thickness (CCT) readings of 284 healthy, nonglaucoma subjects, without previous ocular surgery, were measured with ORA and Corvis ST. Only data from right eyes were analyzed. The mean values of CCT measurements by the ORA versus Corvis ST were compared with the paired sample t test. Bland-Altman plots and 95% limits of agreement (95% LOA) were used to assess the agreement between the measurements of the two devices. The mean (± standard deviation) age of the participants was 28.0 ± 4.9 years, and 36.6% were male. The mean CCT measurements were 555 ± 32 µm by the ORA and 536 ± 32 µm with the Corvis ST (P < 0.001). The Pearson correlation coefficient was 0.964 (P < 0.001). The 95% LOA between the ORA and the Corvis ST was 2.2 to 35.9 µm. The ORA measured the CCT up to 35.9 µm greater than Corvis ST. Therefore, the two devices may not be used interchangeably for measuring CCT.

Central Corneal Thickness in Childhood Cataract.

We explored elevated central corneal thickness (CCT) in children with cataracts as possibly reflecting preexisting corneal malformation related to specific cataract morphology. All children consecutively seen during the study periods who had cataracts and corneal pachymetry as part of their routine care were enrolled at academic centers in large cities of Canada and the United States. Study data collected included age, sex, CCT, and cataract morphology. Differences among cataract morphology groups with respect to mean CCT measurements were evaluated and compared with a historical control thickness of 558 μm. A total of 96 children were enrolled in this study. The average subject age was 5.1 years, and 55 children (57%) were female. The mean CCT value for all subjects was 566.1 μm. There was little evidence to conclude that the cataract morphology groups differed from each other (P = 0.65) or from controls with respect to CCT. In children, CCT is likely independent of cataract morphology. This implies that factors other than preoperative malformation are more likely related to elevated CCT observed in children with aphakia and pseudophakia.

Distribution of corneal thickness measured using optical coherence tomography in South African young adults

Background: Corneal thickness measurements have various diagnostic and therapeutic applications. Studies have reported on the distribution of corneal thickness measurements in Caucasian and Asian subpopulations with limited focus on African subpopulations. Aim: The goal of this study was to examine the distribution of corneal thickness measured using optical coherence tomography in a South African young adult population. Setting: The study was conducted at the eye clinic at the University of KwaZulu-Natal. Methods: The study used a quantitative cross-sectional research design and participants were recruited using two-stage random sampling. Seven hundred participants consisting of 50% South African blacks and 50% South African Indians aged between 17 and 30 years were included. The sample included an equal distribution of male ( n = 350) and female ( n = 350) participants. Corneal thickness was measured using the Fourier-domain Optovue iVue100 optical coherence tomographer. As the data from the right and left eyes showed high levels of interocular symmetry, data from only the right eyes were analysed using descriptive and inferential statistics. Results: The mean age of the sample was 20.42 ± 1.80 years. Corneal thickness measurements resembled Gaussian curves ( p ≥ 0.095) and the mean central corneal thickness (CCT) was 501.91 µ m. Corneal thickness at the thinnest point was 495.73 µ m and 1.23% thinner than the mean CCT measurement ( p < 0.001). Males had slightly higher corneal thickness measurements than females but these differences (0.35 µ m – 3.93 µ m) were not significant ( p ≥ 0.137). Corneal thickness varied significantly with refractive error and was lowest in emmetropes followed by myopes and then hyperopes. Conclusion: Corneal thickness measurements are normally distributed in South African young adults. The mean CCT is different from that reported in other populations and lower than the calibrated CCT measurement for Goldmann applanation tonometry. Eye care personnel should consider the characteristics of corneal thickness measurements and its implications on intraocular pressure measurements when examining South African individuals.

Outcome of UVA-Riboflavin collagen cross-linking of cornea in patients with keratoconus

Purpose: In this study, we aimed to show changes of central corneal thickness and effects of treatment on visual acuity after corneal collagen cross-linking in keratoconus patients.Materials and Methods: 26 eyes of 51 patients with keratoconus who undergone corneal collagen cross-linking were included in to the study. Central corneal thickness measurements and best corrected visual acuity were recorded before and after 1st and 6th month of corneal collagen cross-linking operation.Results: Mean central corneal thickness measurements were recorded as; 435,43±44,35 μm, 376,68±66,55 μm and 392,62±64,21 μm before and after 1st and 6th month of corneal collagen cross-linking, respectively. There was a statistically significant difference between pre-op and postop 1st month, pre-op and postop 6th month and post-op 1st month and post-op 6th month central corneal thickness measurements. Also, there was a statistically significant increase in best corrected visual acuity after the operation.Conclusion: There was a statistically significant difference between pre-op, post-op 1st month and postop 6th month central corneal thickness and best corrected visual acuity measurements.

Anizohipermetropik ambliyopisi olan yetişkinlerin ön segment parametrelerinin Sirius topografi ile değerlendirilmesi

Aim: To evaluate anterior segment parameters in the eyes of adults with anisohypermetropic amblyopia using the Sirius topography device.Materials and Methods: Forty-eight patients with anisohypermetropic amblyopia were prospectively evaluated along with a control group of 45 healthy patients. All patients were examined with the Sirius topography system under cycloplegic and non-cycloplegic conditions. The anterior and posterior mean keratometry values, central corneal thickness (CCT), anterior chamber depth (ACD), corneal volume (CV), and anterior chamber volume (ACV) measurements were compared among groups.Results: No significant difference was found in the anterior and posterior mean keratometry values, CCT, ACD, CV, and ACV measurements between amblyopic, fellow, and control eyes under cycloplegic and non-cycloplegic conditions (p&amp;gt;0.05).Conclusion: This study shows that the anterior segment parameters measured by the Sirius topography device among amblyopic, fellow, and control eyes do not differ under both cycloplegic and non-cycloplegic conditions.

Correlation between central corneal thickness and myopia.

To analyze the correlation between central corneal thickness (CCT) and myopia in refractive surgery candidates. Patients that underwent myopic laser refractive surgery between January 2000 and December 2014 were included. Preoperative CCT was measured by ultrasonic pachymetry, and refractive status determined by manifest and cycloplegic refraction. A total of 30,245 individuals were included. Mean age was 28.2±8.6years, and 45.9% were female. Mean refractive error was 4.02±2.17 D (range 0.25-19.5), and the mean CCT measurement was 533.5±35.5µm (range 404-794). Younger individuals showed higher degree of myopia (p=0.006). No difference in CCT was found between women and men (533.0±35.1 and 533.6±35.9µm, respectively, p=0.19). Though CCT showed no correlation with age (p=0.226) participants above age 40 expressed higher CCT values (p<0.001). No significant correlation was found between the CCT and cylinder (p>0.05). An increase in mean keratometry was associated with a decrease in CCT (p<0.001). There was a direct correlation between the degree of myopia and CCT (r=0.94, p<0.001). The result remained the same after adjusting for age group and gender in stepwise backward regression analysis (p<0.001). Central corneal thickness is correlated with the degree of myopia among adults undergoing refractive surgery.

Comparison of central corneal thickness with four noncontact devices: An agreement analysis of swept-source technology.

Purpose:The purpose of this study was to compare the central corneal thickness (CCT) measurements of four noncontact devices in healthy eyes.Materials and Methods:In a sample of 45 healthy controls, CCT was measured using an optical biometer (IOLMaster 700) based on swept-source optical coherence tomography (SS-OCT), high-resolution rotating Scheimpflug camera system (Pentacam HR), spectral-domain OCT (SD-OCT) device with an anterior segment module (Spectralis), and noncontact pachymetry (NCP) device (Topcon TRK-2P). Agreement among the devices was analyzed using mean differences (i.e., bias) and Bland–Altman analysis with 95% limits of agreement (LoA).Results:Mean CCT measurements were 537.5 ± 47.5 μm for SS-OCT optical biometer, 532.3 ± 43.8 μm for Scheimpflug system, 521.3 ± 44.7 μm for SD-OCT device, and 518.0 ± 43.1 μm for NCP (P < 0.001). The SD-OCT device and NCP showed the closest agreement, with a bias of 2.6 μm (95% LoA, −3.6–8.8 μm), whereas the SS-OCT optical biometer and NCP showed the least agreement, with a bias of 18.7 μm (95% LoA, −2.1–39.5 μm). Bias was 16.1 μm (95% LoA, −3.1–35.3 μm) for SS-OCT optical biometer and SD-OCT, 5.1 μm (95% LoA, −6.8–17.0 μm) for SS-OCT optical biometer and Scheimpflug system, 10.9 μm (95% LoA, −15.1–36.9 μm) for SD-OCT device and Scheimpflug system, and 13.6 μm (95% LoA, −5–32.2 μm) for Scheimpflug system and NCP.Conclusions:SS-OCT optical biometer overestimates CCT measurements compared to Scheimpflug system, SD-OCT device, and NCP. Given mean differences and range variations in CCT measurements between devices, SS-OCT optical biometer and Scheimpflug system are interchangeable as are SD-OCT and NCP.

Validity of Tono-pachymetry for Measuring Corrected Intraocular Pressure in Non-surgical and Post-photorefractive Keratectomy Eyes.

PurposeTo 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.MethodsFor 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.ResultsThe 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.ConclusionsThe 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.

Central Corneal Thickness After Cross-linking Using High-Definition Optical Coherence Tomography, Ultrasound, and Dual Scheimpflug Tomography: A Comparative Study Over One Year

To assess central corneal thickness (CCT) and corneal haze in keratoconus eyes following corneal cross-linking (CXL). Prospective noncomparative case series. Forty patients (44 eyes) with keratoconus that had serial evaluation for CCT, following CXL, usinghigh-definition optical coherence tomography (HD-OCT), ultrasound pachymetry (USP), and dual Scheimpflug tomography. CCT was measured at baseline, then at 2weeks and 1, 3, 6, and 12months postoperatively. The mean baseline CCT measurements were 470.02μm, 469.79μm, and 466.66μm using the HD-OCT, the USP, and dual Scheimpflug tomography, respectively (P= .91). Following CXL, the mean CCT measurements by dual Scheimpflug, at all follow-up periods, were lower compared to mean baseline reading (P < .003). The mean CCT measurements by the HD-OCT and USP were similar to baseline readings except for the thicker readings at the 2-week follow-up visit. Overall, the mean CCT obtained by the USP was similar to that obtained by the HD-OCT throughout the 12-month period. However, the mean CCT measurements obtained by dual Scheimpflug tomography were statistically and clinically significantly lower than those obtained by both HD-OCT and USP at all follow-up visits. USP and HD-OCT showed better agreement in CCT readings at all visits, and may better estimate the true CCT following CXL as compared to dual Scheimpflug tomography. The lower mean CCTpost-CXL as measured by the latter seems to be correlated with the amount of haze that develops aftercross-linking.

Comparison of Ultrasound and Scheimpflug Methods for Central Corneal Thickness

Aim: The central corneal thickness (CCT) of healthy individuals was measured with an ultrasonic pachymeter (UP) and the Scheimpflug imaging system (SIS) and the results were compared to evaluate the agreement between the two methods in this study. Materials and Methods: The 61 subjects who had no ocular pathology or systemic disease except blepharitis were included in the study. CCT measurements of all subjects were performed with the UP (Sonomed 300P Pacscan) and SIS (Nidek Optical biometer AL-Scan) devices and the results were compared. The t test and the Bland-Altman plot were used as the statistical methods. Results: The study sample consisted of 61 cases including 20 males and 41 females. The mean age was 41.8±12.4 (20-58) years for the males and 46.2±9 (24-60) years for the females with no statistically significant difference (P=0.116). The mean CCT measurement of all the 61 subjects was 544.5±31 μm in the right eyes and 547.3±33 μm in the left eyes with UP, 530.7±27.6 μm in the right eyes and 531.6±25.5 μm in the left eyes with SIS. The CCT in the SIS results was an average of 13.8 μm thinner than the UP results in the right eye, 15.7 μm in the left eye and this difference Original Research Article Ersekerci et al.; BJMMR, 8(8): 677-683, 2015; Article no.BJMMR.2015.493 678 was statistically significant (p=0.001 in right and left eyes). A high degree of agreement was found between the two methods with the Bland-Altman plot. Conclusion: A high degree of agreement was found between SIS and UP regarding CCT measurements and the mean SIS results were 13.8 μm and 15.7 μm thinner than the UP results in the right eyes and left eyes respectively.

Comparison of Measurement of Central Corneal Thickness with Spectral Domain Optical Coherence Tomography and Standard Ultrasonic Pachymeter in Premature Infants.

Purpose. To evaluate the repeatability of measurement of central corneal thickness (CCT) by spectral domain optical coherence (SD-OCT) in premature infants and compare it to CCT measurement by ultrasonic pachymetry (USP). Methods. Three CCT measurements of the left eyes of 50 premature infants were obtained by SD-OCT using the iVue system. 10 CCT measurements of each 28 left eyes of 28 infants were obtained by USP using the Pacscan 300P system. Bland-Altman plots were developed and the limit of agreement (LoA) was determined to compare the mean of the SD-OCT and USP measurements. Results. No statistically significant difference was found among the 3 CCT measurements by SD-OCT. Both USP and SD-OCT have been performed for only left eyes of 28 of the 50 babies. Those results have been compared with each other. A statistically significant difference was found between the mean CCT measurements by SD-OCT and USP (p < 0.05). The LoA between the SD-OCT and USP measurements ranged from 11.4 to −64.1. Conclusions. CCT can be measured using the iVue SD-OCT system with a high level of repeatability. Although measurement of CCT by SD-OCT and USP is highly correlated, the 2 systems cannot be used interchangeably in premature infants.

Precision of corneal thickness measurements obtained using the scheimpflug-placido imaging and agreement with ultrasound pachymetry.

Purpose. To assess the reliability and comparability of measuring central corneal thickness (CCT) and thinnest corneal thickness (TCT) using a new Scheimpflug-Placido analyzer (TMS-5, Japan) and ultrasound (US) pachymetry. Methods. Seventy-six healthy subjects were prospectively measured 3 times by 1 operator using the TMS-5, 3 additional consecutive scans were performed by a second operator, and ultrasound (US) pachymetry measurements were taken. The test-retest repeatability (TRT), coefficient of variation (CoV), and intraclass correlation coefficient (ICC) were calculated to evaluate intraoperator repeatability and interoperator reproducibility. Agreement among the devices was assessed using Bland-Altman plots and 95% limits of agreement (LoA). Results. The intraoperators TRT and CoV were <19 μm and 2.0%, respectively. The interoperators TRT and CoV were <12 μm and 1.0%, respectively, and ICC was >0.90. The mean CCT and TCT measurements using the TMS-5 were 15.97 μm (95% LoA from −26.42 to −5.52 μm) and 20.32 μm (95% LoA from −30.67 to −9.97 μm) smaller, respectively, than those using US pachymetry. Conclusions. The TMS-5 shows good repeatability and reproducibility for measuring CCT and TCT in normal subjects but only moderate agreement with US pachymetry results. Caution is warranted before using these techniques interchangeably.

Short-term Effects of Intravitreal Bevacizumab on Cornea and Anterior Chamber

Purpose: To determine the short-term effects of single-dose intravitreal bevacizumab injection on central corneal thickness (CCT), simulated keratometry (Sim K), anterior chamber depth (ACD), iridocorneal angle (ICA) and intraocular pressure (IOP) measurements.Design: Prospective, nonrandomized, interventional clinical trial.Materials and Methods: Forty-three eyes of 43 patients aged between 41 and 78 years (average 62 ± 13 years) received an intravitreal injection of 2.5 mg/0.1 mL bevacizumab. Patients who had not undergone additional intravitreal anti-vascular endothelial growth factor therapy within 6 months were included in the study. CCT, Sim K, ACD and ICA measurements were obtained with Sirius Topographer. IOP measurements were taken after topographic measurements with Goldmann applanation tonometer. The CCT, ACD, ICA and IOP measurements were taken before and after 3rd, 15th days and 1st month of intravitreal bevacizumab injection.Results: Pre- and postinjection of 3rd, 15th days and 1st month CCT (p = 0.999), Sim K (p = 0.746), ACD (p = 0.996), ICA (p = 0.632) and IOP (p = 0.707) measurements were not statistically different. Mean CCT (p = 1.000), Sim K (0.972), ACD (p = 0.998), ICA (0.667) and IOP (0.951) values were similar before and after 3rd day of bevacizumab injection. Mean CCT (p = 0.999), Sim K (p = 0.994), ACD (p = 1.000), ICA (p = 0.999) and IOP (p = 1.000) measurements were also similar before and after 15th day of injection. Preinjection and 1st month of postinjection CCT (p = 0.999), Sim K (p = 0.932), ACD (p = 0.998), ICA (p = 1.000) and IOP (p = 0.741) measurements did not change significantly.Conclusions: Single-dose intravitreal bevacizumab injection does not affect CCT, Sim K, ACD, ICA and IOP in short-term period.

Correlation between central corneal thickness and myopia in Taiwan

The aim of the study was to explore the correlation between central corneal thickness (CCT) and the degree of myopia in Taiwanese adults. A total of 528 individuals were enrolled to undergo myopic laser refractive surgery from January 2004 to December 2006. Preoperative CCT was measured using the Orbscan corneal topography system and refractive status was determined by cycloplegic spherical equivalent. The relationship between CCT and refractive error was investigated by interindividual and intraindividual analyses. Participants had a mean age of 34.8 ± 7.3 years, and 79.9% were female. The mean refractive error was −7.27 ± 2.96 diopters and the mean CCT measurement was 560 ± 35 μm. CCT revealed that there was no association with age. However, CCT was significantly (p = 0.012) less in females than in males. The CCT also showed no significant association with refractive error (p = 0.49). Among the 67 participants with myopic anisometropia, the mean difference between both eyes was 3.09 ± 1.06 diopters. There was no association between the intereye CCT difference and refractive error (p = 0.57). The results remained the same after adjusting for age and sex. In conclusion, there was no correlation between CCT and the degree of myopia among adults in Taiwan. These data might contribute to the ongoing discussion about the role of CCT in the higher incidence of development and progression of glaucoma in myopic individuals.