Difference In Mean Central Corneal Thickness Research Articles

Effect of Age and Parity on Physiological Changes in the Eye During Pregnancy: A Prospective Longitudinal Study.

The hormonal and metabolic changes that occur during uncomplicated pregnancy affect the eye. The effects of maternal age and parity on the physiological eye changes in pregnancy have been scarcely documented. To determine these effects on some physiological eye changes that occur in pregnancy. A longitudinal study involving consecutively recruited 140 pregnant women aged 18-48 years attending antenatal clinic at the University of Nigeria Teaching Hospital, Enugu. A structured questionnaire was administered to consenting women, after which the Schirmer test, tear break-up time (tBUT), corneal sensitivity, central corneal thickness (CCT), and intraocular pressure (IOP) was measured in the second and third trimesters, and six weeks after delivery. The mean CCT showed a significantly greater increase among the multiparous (≥para 2) women in both the second and third trimesters compared with the primigravida/primiparous women (P = 0.032 and 0.049, respectively). There was no difference in mean CCT between the two parity groups at six weeks postpartum. Women aged 18-35 years showed a significantly greater increase in the mean CCT in the second trimester compared to those aged less than 35 years (P = 0.04). However, there was no difference in the mean CCT between the different age groups in the third trimester and at six weeks postpartum. The age and parity of women affect their level of CCT changes in pregnancy. Consideration of this effect may guide clinicians on their approaches to eye care and treatment during pregnancy.

Compare Mean Central Corneal Thickness with Ultrasound Pachymetry and Spectral-Domain Optical Coherence Tomography in Patients Presenting with Glaucoma

Background: The optic nerve damage with the ultimate loss of vision resulting from a clutch of diseases named Glaucoma. In many conditions including, corneal dystrophies, corneal edema, and endothelial diseases of the cornea, the important biometric is Central corneal thickness (CCT). Objective: To find the difference in mean CCT with spectral-domain optical coherence tomography and ultrasound pachymetry in patients presenting with Glaucoma. Material & Methods: The study design opted was the observational cross-section. The study was done in tertiary care hospital. A total of 180 patients were registered for the present study. Both techniques noted the CCT value of all patients. Once the data was collected, it was stored electronically and analyzed by using SPSS version 20.0. Results: 40.00±11.50 years was the average age of all the patients. There were 89(49.44%) males and 91(50.56%) females. The mean CCT was 531.01±28.54µm on OCT and 530.01±29.74µm on USP. The mean difference in CCT was 3.93±3.13µm between OCT & USP. The difference was statistically insignificant (p<0.05). Conclusion: There is a statistically insignificant difference between the mean CCT with USP and spectral domain OCT patients presenting with Glaucoma. Keywords: Glaucoma, Optical Coherence Tomography, Central Corneal Thickness.

Split-Window OCT biometry in pseudophakic eyes.

To determine the utility of Split-Window optical coherence tomography OCT (SW-OCT) biometry in measuring ocular axial dimensions as well as imaging the intraocular lens (IOL) and posterior capsule in pseudophakic eyes. Sixty-nine pseudophakic eyes of 69 subjects were enrolled in the study. The results of SW-OCT biometry implemented in the SD OCT device for posterior and anterior segment imaging (REVO NX, Optopol Technology) were compared with those obtained with the SS-OCT-based biometer IOLMaster 700 (Carl Zeiss Meditec). Differences in measurement values between the two biometers were determined using the paired t-test. Agreement was assessed through intraclass correlation coefficients (ICC) and Bland-Altman plots. The correlation between measurements obtained with SW-OCT and SS-OCT was very high (ICC for: axial length (AL) = 1.000; anterior chamber depth (ACD) = 0.997; IOL thickness (IOL LT) = 0.997; central corneal thickness (CCT) = 0.987). The mean AL measurement difference was 0.003 ± 0.021 mm (the 95% LoA ranged from -0.04 to 0.05); the mean ACD difference was -0.009 ± 0.025 mm (95% LoA, -0.06 to 0.04); mean LT difference was 0.001 ± 0.021 mm (95% LoA, -0.04 to 0.04); and mean CCT difference was 1.4 ± 5.4 μm (95% LoA, -9 to 12). The study shows small, non-significant differences between the biometric measurements obtained with REVO NX SW-OCT and IOLMaster 700 SS-OCT in pseudophakic eyes. However, SW-OCT offered significantly lower ACD and LT measurement failure rates. With high-resolution imaging, SW-OCT enables accurate assessment of IOL position relative to the posterior capsule and visualization of capsular fibrosis.

Effect of Prostaglandin Analogues on Central Corneal Thickness: 3-Year Follow-up Results.

Purpose To evaluate the effects of each subgroup of prostaglandin analogues (PGAs) on central corneal thickness (CCT) in patients with normal tension glaucoma (NTG).Methods We retrospectively reviewed 55 eyes of 55 patients with NTG who were receiving PGA therapy. Patients who were treated with 0.005% latanoprost (16 eyes), 0.0015% tafluprost (16 eyes), or 0.004% travoprost (23 eyes) monotherapy were included. CCT assessments were performed at baseline and 1, 2, and 3 years after initiation of treatment.Results In the NTG group, the mean CCT showed a decreasing trend, and there was a significant difference in mean CCT at 1, 2, and 3 years compared with baseline (baseline, 538.16 ± 32.14; 1 year, 526.55 ± 37.30 µm [p = 0.00]; 2 years, 521.67 ± 36.79 µm [p = 0.00]; 3 years, 520.43 ± 36.88 µm [p = 0.00]). The reduction of CCT was confirmed by subgroup analysis. In the 0.005% latanoprost group, mean CCT was decreased at 1 year (p = 0.11), 2 years (p = 0.00), and 3 years (p = 0.02). In the 0.0015% tafluprost group and the 0.004% travoprost group, mean CCT was also significantly decreased at all years (p = 0.00). No statistical difference was observed between the NTG subgroups (p = 0.06).ConclusionsTopical therapy with PGAs appeared to cause a significant decrease in CCT reduction in patients with NTG. A long-term follow-up study including more participants is needed.

OCT Biometry (B-OCT): A New Method for Measuring Ocular Axial Dimensions.

Purpose To present a new method of measuring ocular axial dimensions, termed OCT biometry (B-OCT). Design Observational cross-sectional study and evaluation of new diagnostic technology. Methods B-OCT was implemented in the spectral domain OCT device for posterior and anterior segment imaging (REVO NX, Optopol Technology). A total of 349 eyes (214 of healthy subjects, 115 of patients with cataract, and 20 with severe macular diseases) were enrolled in the study. The results of B-OCT were compared to swept source OCT-based IOLMaster 700 (Carl Zeiss Meditec). Differences in measurement values between the two biometers were determined using the paired t-test. Agreement was assessed through intraclass correlation coefficients (ICCs) and Bland–Altman plots. Results B-OCT obtained with REVO NX provides excellent interobserver reproducibility (ICC for: axial length (AXL) = 1.000; central corneal thickness (CCT) = 0.933; anterior chamber depth (ACD) = 0.933; lens thickness (LT) = 0.985) and intraobserver repeatability (ICC for: AXL = 1.000; CCT ≥ 0.994; ACD = 0.998; LT ≥ 0.993). The correlation between measurements made using both devices was outstanding (ICC for: AXL, healthy = 1.000; AXL, cataractous = 1.000; ACD, healthy = 0.998; ACD, cataractous = 0.997; LT, healthy = 0.998; LT, cataractous = 0.997; CCT, healthy = 0.989; CCT, cataractous = 0.979). The mean AXL measurement difference in healthy eyes was −0.001 ± 0.016 mm (the 95% LoA ranged from −0.034 to 0.031); mean ACD difference was 0.000 ± 0.024 mm (95% LoA, −0.047 to 0.047); mean LT difference was −0.002 ± 0.024 mm (95% LoA, −0.050 to 0.046); and mean CCT difference was −0.8 ± 5.1 μm (95% LoA, −10.81 to 9.26). The mean AXL measurement difference in cataractous eyes was −0.003 ± 0.022 mm (95% LoA, −0.046 to 0.039); mean ACD difference was 0.003 ± 0.029 mm (95% LoA, −0.054 to 0.059); mean LT difference was −0.002 ± 0.025 (95% LoA, −0.051 to 0.048); and mean CCT difference was 2.7 ± 6.4 μm (95% LoA, −9.80 to 15.7). Conclusion The study shows small, nonsignificant differences between the biometric measurements obtained with REVO NX B-OCT and IOLMaster 700, which is of high significance for IOL power selection. As B-OCT utilizes a conventional OCT device, the measurements of the ocular axial dimensions are combined with high-resolution macular scans for the simultaneous assessment of central retina as a part of screening for macular pathology. The presented method is the first spectral domain OCT-based biometry technique and the only one integrated into a standard OCT device. Thus, it brings novel functionality to OCT technology.

Distribution of central corneal thickness and intraocular pressure in emmetropic eyes of healthy children of Palestine: a representative cross-sectional study.

To determine the distributions of central corneal thickness (CCT) and intraocular pressure (IOP) in emmetropic eyes of healthy children of Palestine. This representative cross sectional study included a total of 1156 eyes from 578 healthy school children aged 7-15y. Inclusion criteria included emmetropia, no previous history of ocular or systemic diseases, no previous history of contact lens use, and the availability of both eyes. CCT and IOP were measured using ultrasound pachymeter and Goldmann applanation tonometer, respectively. The relationship of the results with age and gender was investigated. The mean age of school children was 11.13±2.8y. Mean CCT was 542.2±37.4 and 544.3±39.2 µm for right and left eyes, respectively. Mean IOP was 12.5±2.2 and 12.3±2.2 mm Hg for right and left eyes, respectively. A positive correlation was observed between CCT and IOP of the right eye (P<0.001, R=0.358) and CCT and IOP of the left eye (P<0.001, R=0.324). No significant differences were observed in CCT and IOP due to age or gender (P>0.05). There were significant differences in mean CCT and IOP between right and left eyes (P=0.004, P=0.001, respectively). A population profile of CCT and IOP is established in Palestinian children for the first time. Mean CCT is comparable to some studies but differ from others. Mean IOP is considerably lower than that of majority children of other ethnic groups. Intereye difference of more than 36 µm in CCT, and 5 mm Hg in IOP should prompt evaluation for potential ocular disorders.

Central corneal thickness measurement using ultrasonic pachymeter, optical coherence tomography, and TMS-5 topographer

AIM:This study aimed to compare the central corneal thickness (CCT) measurements using Optical Coherence Tomography (OCT) and TMS-5 topographer with that taken with the gold standard digital Ultrasonic pachymeter (USP).MATERIALS AND METHODS:A total of 61 subjects (122 eyes) were prospectively and consecutively studied in a period from June 2016 to June 2017 at Sudan Eye Centre (SEC), Khartoum, Sudan. Besides the visual and refractive data, measurements of CCT were taken using OCT, TMS-5 and USP. Data analyzed using SPSS software for windows (IBM SPSS 20, IBM Corp., Armonk, NY).RESULTS:A statistically significant differences in mean CCT was detected between the three instruments (P < 0.001). USP was found to measure the CCT 29μm thicker than OCT and 22μm thicker than TMS-5 topographer. A significant difference was also found between OCT and TMS-5. OCT found to give the lower values of CCT compared to both USP and TMS-5 topographer. Further analysis showed that the three procedures were significantly and strongly correlated to each other (USP vs OCT, r = 0.77), (USP vs TMS-5, r = 0.78) and (OCT vs TMS-5, r = 0.80).CONCLUSION:Mean central corneal thicknesses (CCT) were comparable among OCT, TMS-5 topographer and the gold standard USP. However, there is a reproducible systematic difference between CCT measurements taken with the three devices. It is important to note in clinical practice, that measurements acquired by these three modalities are not directly interchangeable.

Repeatability and Agreement of Orbscan II, Pentacam HR, and Galilei Tomography Systems in Corneas With Keratoconus

To assess the repeatability and agreement of keratometry and pachymetry measurements obtained using 3 tomographers in eyes with keratoconus. Reliability analysis. setting: Institutional. Fifty eyes of 50 participants with keratoconus. observational procedure: Steep keratometry, flat keratometry, central corneal thickness (CCT), and thinnest corneal thickness (TCT) measurements using Galilei, Orbscan II, and Pentacam HR. Repeatability was assessed using within-subject standard deviation (SW), coefficient of variation (CV), and intraclass correlation coefficient (ICC). Bland-Altman plots and 95% limits of agreement (LoA) were used to evaluate agreement between device pairs. For all studied parameters, ICC was >0.97 with the least repeatable measurements obtained using Orbscan II. Mean steep keratometry values were similar while mean flat keratometry values were significantly different between all devices. The Galilei and Pentacam HR had the lowest 95% LoA for both CCT and TCT. There were no significant differences in mean CCT between Galilei and Pentacam HR. Mean Orbscan II CCT measurements were not significantly different overall but had wide 95% LoA with Pentacam HR (-47.95 to 58.09μm) and Galilei (-43.70 to 53.91μm). Mean Orbscan II CCT measurements were significantly lower when an acoustic factor of 0.92 was applied (-33.6μm vs Pentacam HR, P < .001;-33.6μm vs Galilei; P < .001). Keratometric and pachymetric measurements of keratoconic eyes obtained by Galilei, Orbscan II, and Pentacam were disparate. Measurements were less repeatable with Orbscan II compared with Pentacam HR and Galilei, although overall repeatability was high for all instruments.

Influence of Ultrastructural Corneal Graft Abnormalities on the Outcome of Descemet Membrane Endothelial Keratoplasty

To investigate if ultrastructural alterations in the Descemet membrane (DM) are correlated with the clinical outcome after Descemet membrane endothelial keratoplasty (DMEK). Retrospective cohort study. setting: Institutional, single-center. One hundred and twelve residual DM specimens obtained after DM stripping. Incidence of ultrastructural abnormalities in transmission electron microscopy, graft detachment rate, graft failure rate, best-corrected visual acuity (BCVA), endothelial cell density (ECD), and central corneal thickness (CCT). Examination dates were on the day before DMEK and 1, 3, 6, and 12months after surgery. Abnormalities in the ultrastructure of DM were found in 16 of 112 specimens (14%) (abnormal DM group), comprising deposits of long-spacing collagen, fine filaments (proteoglycans), a posterior collagenous layer, pseudoexfoliative material, and guttae. The secondary graft failure rate was significantly higher in the abnormal DM group compared with the normal DM group (P= .001). There was a trend for an increased graft detachment rate in the abnormal DM group (11/16) compared with the normal DM group (42/96) (P= .103). There was no significant difference in mean CCT and ECD after surgery. Mean CCT in the eyes with graft failure in the abnormal DM group at the last follow-up before regrafting was 850μm, indicating endothelial failure with stromal edema. This study reveals a correlation between ultrastructural alterations of DM in donor corneas and the graft failure rate after DMEK. Thus, graft failure after DMEK not only is determined by surgical trauma and postoperative events but may also be influenced by intrinsic, graft-specific features.

Morphometric changes of corneal endothelial cells in pseudoexfoliation syndrome and pseudoexfoliation glaucoma

ObjectiveTo evaluate the corneal endothelial morphometry and central corneal thickness (CCT) in pseudoexfoliative (PEX) eyes with and without glaucoma and to compare with normal eyes and eyes with primary open-angle glaucoma (POAG). MethodA total of 166 patients were included in this study: 36 eyes with pseudoexfoliation syndrome (PXS), 30 eyes with pseudoexfoliation glaucoma (PXG), 40 eyes with POAG, and 60 normal eyes. Corneal endothelial cell density (ECD), coefficient of variation (CV) in cell size, and percentage of hexagonal cells were measured using a non-contact specular microscope, whereas CCT was measured with an ultrasonic pachymeter. ResultsECD and percentage of hexagonal cells were lower in PEX groups and in the POAG group compared with normal eyes, while the CV in cell size was greater. There was a tendency for greater cell loss and morphological abnormalities of the corneal endothelial cells in PXG eyes compared to PXS eyes, when all pseudoexfoliative eyes were analyzed together. Changes in endothelial cells increased with age. There were no significant differences in mean CCT between the four groups. ConclusionEndothelial cell density is significantly decreased, and pleomorphism and polymegathism of cells are increased in PEX eyes, particularly when intraocular pressure is high.

Cambios morfométricos de las células del endotelio corneal en el síndrome pseudoexfoliativo y glaucoma pseudoexfoliativo

ObjetiveTo evaluate the corneal endothelial morphometry and central corneal thickness (CCT) in pseudoexfoliative (PEX) eyes with and without glaucoma and to compare with normal eyes and eyes with primary open-angle glaucoma (POAG). MethodA total of 166 patients were included in this study: 36 eyes with pseudoexfoliation syndrome (PXS), 30 eyes with pseudoexfoliation glaucoma (PXG), 40 eyes with POAG, and 60 normal eyes. Corneal endothelial cell density (ECD), coefficient of variation (CV) in cell size, and percentage of hexagonal cells, were measured using a non-contact specular microscope, whereas CCT was measured with an ultrasonic pachymeter. ResultsECD and percentage of hexagonal cells were lower in PEX groups and in the POAG group compared with normal eyes, while the CV in cell size was greater. There was a tendency for greater cell loss and morphological abnormalities of the corneal endothelial cells in PXG eyes compared to PXS eyes, when all pseudoexfoliative eyes were analyzed together. Changes in endothelial cells increased with age. There were no significant differences in mean CCT between the four groups. ConclusionEndothelial cell density is significantly decreased, and pleomorphism and polymegathism of cells are increased in PEX eyes, particularly when intraocular pressure is high.

Corneal Biomechanical Properties and their Correlates with Healing Process after Descemetic versus Pre-Descemetic Lamellar Keratoplasty

To evaluate the influence of the wound-healing process on corneal biomechanics in patients after 2 types of deep anterior lamellar keratoplasty: Descemetic with total stromal resection vs pre-Descemetic with deep stromal dissection. This prospective comparative study consisted of 32 eyes of 32 patients. Patients were divided into 2 groups: Descemetic (17 eyes) and pre-Descemetic (15 eyes). Reichert ocular response analyzer was used to measure corneal hysteresis (CH) and corneal resistance factor (CRF) at 1 and 3 months postoperatively. Central corneal thickness (CCT) was measured using ultrasonic pachymetry. In vivo confocal microscopy was also used to study the corneal wound-healing process and to correlate these events with the corneal biomechanics postoperatively in both groups. Both mean CH and mean CRF were significantly lower in the Descemetic than the pre-Descemetic group at 1 and 3 months postoperatively (p≤0.0001). The reflectivity of activated keratocytes at both the interface and wound edge was less in the Descemetic than the pre-Descemetic group at all times as revealed by the confocal microscopy. No statistically significant difference in mean CCT was found between both groups at 1 and 3 months. Subsequent and progressive decrease in interface reflectivity of activated keratocytes was presented in both groups. Healing process at the interface is key to optimal corneal integrity. In the pre-Descemetic group, stroma-to-stroma healing stimulated more activated keratocytes and hence stronger healing response, providing superior corneal biomechanics. Significant positive correlation between the intensity of the keratocyte activation and corneal integrity was found.

Corneal Thickness in Keratoconus: Comparing Optical, Ultrasound, and Optical Coherence Tomography Pachymetry

To compare the central and peripheral pachymetry measurements determined using Orbscan IIz (Bausch & Lomb, Rochester, NY), Visante optical coherence tomography (OCT; Carl Zeiss Meditec, Dublin, CA), and RTVue OCT (Oculus Technologies, Wynwood, WA) with ultrasound pachymetry in eyes with established keratoconus and to evaluate the agreement between them. Evaluation of diagnostic technologies. One hundred six eyes of 67 consecutive patients with a clinical diagnosis of keratoconus ranging in age from 12 to 40 years. Central corneal thickness (CCT) was determined by all the 4 techniques. Peripheral corneal thicknesses were determined using Orbscan IIz, Visante OCT, and RTVue at 8 points (superior, inferior, temporal, nasal, superior-temporal, inferior-temporal, superior-nasal, and inferior-nasal) all in the 5.0- to 7.0-mm arcuate zone. Central and peripheral keratoconus thickness. Ultrasound pachymetry determined significantly higher CCT values than Orbscan IIz (P<0.001), Visante (P<0.001), and RTVue (P = 0.037), with a mean ± standard deviation difference of 14±3 μm, 13±2 μm, and 5±3 μm, respectively. The mean CCT difference was minimal (1±3 μm; P = 0.69) between the Orbscan IIz and Visante. A strong correlation was found (r>0.80) between all the CCT measurement techniques. Orbscan IIz significantly overestimated the peripheral thickness compared with the rest, and the mean differences ranged between 21 and 60 μm. Mean peripheral thickness differences between RTVue and Visante OCT always remained less than 20 μm. Weak correlations and larger limits of agreement were found between the techniques in thinner and peripheral zones. Orbscan IIz, Visante, RTVue, and ultrasound pachymetry show high correlation, although Orbscan IIz and Visante significantly underestimated CCT measurements compared with ultrasound pachymetry in keratoconus. Orbscan IIz significantly overestimated peripheral corneal thickness compared with RTVue and Visante.

Comparison of central corneal thickness using optical low-coherence reflectometry and spectral-domain optical coherence tomography

To assess intraobserver and interobserver reliability of central corneal thickness (CCT) measurements using optical low-coherence reflectometry (OLCR) technology and its agreement with spectral-domain optical coherence tomography (SD-OCT). Rio Hortega University Hospital, Valladolid, Spain. Evaluation of diagnostic technology. To analyze OLCR intraobserver repeatability, 1 examiner obtained 4 successive measurements. To study interobserver reproducibility, a different examiner obtained another CCT measurement. To determine agreement with SD-OCT, the first examiner also obtained CCTs. Intraobserver and interobserver within-subject standard deviation (S(w)), coefficient of variation (CV(w)), and limits of agreement (LoA) were obtained for OLCR reliability analysis; for study agreement, data were analyzed using the paired-sample t test and the LoA were calculated. For OLCR intraobserver repeatability, the S(w) and precision (1.96×S(w)) were 2.33 and 4.56 μm, respectively. The intraobserver CV(w) was 0.42%. For interobserver reproducibility, the S(w) and precision were 11.59 and 22.71 μm, respectively; the CV(w) was 2.10%. The mean difference between observers was -1.35 μm (95% confidence interval [CI], -3.97 to 1.26). The width of the LoA was 45.27 μm. The mean CCT difference between OLCR and SD-OCT was 5.68±11.46 μm (95% CI, 8.29-3.08 μm; P=.0001), and the width of the LoA was 44.93 μm. Optical low-coherence reflectometry technology provided reliable intraobserver and interobserver CCT measurements. Although OLCR underestimated the pachymetry by less than 6 μm compared with SD-OCT, its interchangeability fell within the range of interobserver reproducibility. Both noncontact pachymetry measurements seem to be clinically useful and may be used interchangeably with minimum calibration adjustment. No author has a financial or proprietary interest in any material or method mentioned.

Relationship between central corneal thickness and progression of visual field loss in patients with open-angle glaucoma

ObjectiveTo determine whether a relationship exists between central corneal thickness (CCT) and visual field (VF) progression in treated patients with open-angle glaucoma and asymmetric corneal thickness. DesignRetrospective chart review. ParticipantsWe studied 100 charts of patients with open-angle glaucoma and also bilateral CCT and VF data. MethodsCharts from 2 glaucoma subspecialty practices were reviewed. The CCT and the rate of progression and event analysis of visual field data were assessed in all subjects. Subanalysis was performed for subjects whose CCT asymmetry was ≥ 16 μm. ResultsThe mean CCT was 544 ± 40 μm OD and 541 ± 40 μm OS. The mean CCT difference between fellow eyes was 15 ± 11 μm (range, 1 to 52 μm). There was no significant intrasubject difference in the mean deviation (MD) and the pattern standard deviation (PSD) (p =0.917 and p = 0.704, respectively; paired t test). The more advanced VF MDs and PSDs were found in the thin eyes of 47 and 50 subjects, respectively (p = 0.459 and p = 0.317, respectively; χ2). Of the 65 subjects whose visual field indexes were available, 34 had the more rapid visual field index rates of progression in the thin eye (p = 0.400; χ2). Of the 27 subjects for whom event analysis was available, 15 had the worse progression category in the thin eye (p = 0.453, χ2). Subgroup analysis of 48 subjects with ≥ 16 μm CCT asymmetry did not find any significant difference in analyses of field progression between fellow eyes. ConclusionsNo relationship was found between CCT and VF loss in treated patients with primary open-angle glaucoma or normal-tension glaucoma with asymmetrical CCT. Specifically, the thin eye did not have the more advanced VF loss or more rapid VF progression.

The correlation between central corneal thickness, ocular and general parameters

Abstract Purpose To evaluate central corneal thickness (CCT) of normal Lithuanian population,to describe the relationship between CCT, height,weight, body mass index (BMI), intraocular pressure (IOP),refraction ability. Methods In a pilot study 259 adults‐ 125 men and 134 women, whose age ranged in 18‐68 years, were studied. Height, weight and body mass index was determined using a standardized protocol. Non‐cycloplegic refraction was determined by an autorefractor (KR‐8100P, TOPCON). The intraocular pressure was measured by applanation tonometer (Reichert Tono‐pen XL), CCT was measured by contact ultrasound pachymeter (Pocket Pachymeter, Quantel Medical, CP), respectively. Statistical analysis was made using SPSS 17.0 software.Correlations between groups were determined using Pearson two sided correlation coefficient. Results The mean CCT of males was 549.0 (± 33.6) µm for the right eye (OD) and 549.9 (± 33.8) µm for the left eye (OS). The mean CCT of females was 542.6 (± 34.9) µm for OD and 543.1 (± 35.2) µm for OS. Mean height of the examined persons was 173,06 (± 8,27) cm; mean weight – 68,69 (± 11,84) kg; mean value of the body mass index – 22,83 (± 2,95); mean intraocular pressure – 16,07 (± 2,74) mmHg; mean refraction ability – ‐1,56 (± 2,21) D. Pearson two sided correlation coefficient between CCT and subjects’ age was 0,00; CCT and height – 0,108; CCT and weight – 0,093; CCT and BMI – 0,05; CCT and IOP – 0,26; CCT and refraction – 0,047. Conclusion 1.No significant difference in mean CCT was found between the right and left eyes or between male and female subjects. 2. CCT correlated with height, weight and IOP; but not BMI or refraction ability in the overall study group. 3.CCT significantly correlated with height.

Profile of central corneal thickness in diabetics with and without dry eye in a Saudi population

Purpose The aim of this study was to determine the impact of diabetes in patients with and without dry eyes (DE) on central corneal thickness (CCT) measurements. Methods Eighty-six subjects (51 diabetics and 35 controls) participated in the study. Ultrasound pachymetry was used to measure the CCT, whereas tear break-up time (TBUT) and Schirmer tests were conducted for tear assessments. The participants were divided into group 1 (diabetics without DE), group 2 (diabetics with DE), and group 3 (nondiabetics controls). The measurements were compared using analysis of variance. Results The mean (95% confidence interval [CI]) of CCT was 610 (599 to 620), 601 (582 to 618), and 583 (576 to 589) μm, respectively, in diabetics without DE, with DE, and the control groups. There was significant difference in mean CCT between diabetics without DE and controls ( P < 0.0001), but no significant difference in diabetics with DE versus controls ( P > 0.05). The mean (95% CI) values for TBUT and Schirmer tests were 14 (13 to 15), 6 (4 to 6), 14 (14 to 15) seconds, and 21 (19 to 23), 7 (6 to 8), and 20 (19 to 21) mm, respectively, for diabetics without DE, with DE, and the nondiabetic groups. Conclusions DE affects the CCT in diabetic subjects, having a predilection for lower values in those exhibiting DE. In addition, the results also support the view that diabetics tend to present with higher CCT values when compared with nondiabetic patients.

Central Corneal Thickness in Northwestern American Indians/Alaskan Natives and Comparison with White and African-American Persons

To determine the demographic factors associated with central corneal thickness (CCT) in Northwestern American Indians/Alaskan Natives (AI/ANs) and to compare these CCT measurements with those of White and African-American persons. Cross-sectional comparative, observational study. We performed ultrasonic pachymetry (DGH-500 Pachette; DGH Technologies, Exton, Pennsylvania, USA) on a random sample of AI/AN subjects from three randomly selected AI/AN tribes in the Northwest United States (n = 429). Pachymetry also was performed on a convenience sample of White (n = 46) and African-American (n = 33) persons. Our main outcome measure was the average of right and left eye CCT. Average AI/AN CCT was 554.8 +/- 33.9 microm. AI/AN CCT was found to be thicker than that of African Americans (528.5 +/- 33.2 microm) but similar to that of White persons (551.9 +/- 28.3 microm). CCT was greater in AI/AN females than in AI/AN males (557.6 +/- 33.3 microm vs 550.1 +/- 34.5 microm; P = .03). We found no difference in CCT based on percent AI/AN heritage, age, and keratometry readings. We found no significant differences in mean CCT between AI/ANs with glaucoma (556.2 microm) and those who did not have glaucoma (556.6 microm). CCT measurements for the Northwest AI/AN population are similar to those of White persons but thicker than those of African-American persons. Although glaucoma is common in AI/ANs, we did not find an association with thin CCT. We need future studies to explore the risk factors for glaucoma in AI/ANs.

The relationship between central corneal thickness and degree of myopia among Saudi adults

To determine the relationship between central corneal thickness (CCT) and myopia among Saudi adults. In a prospective study, the CCT of 982 myopic eyes and 158 emmetropic eyes as a control group was measured using ultrasound pachymetry at the Eye Consultants Center, Riyadh, Saudi Arabia. The mean myopic spherical equivalent (SE) was -3.7 +/- 2.12 D, range -0.25 to -15.0 D.The mean CCT of the myopic group was 543.8 +/- 35.40 microm, while for the emmetropic group it was 545.7 +/- 27.6 microm. The difference in mean CCT between the two groups was statistically insignificant (P = 0.5). There was no correlation between CCT and the degree of myopic spherical equivalent (r = -0.014, P = 0.939). This clinical study showed that there was no difference in CCT between emmetropic and myopic eyes. CCT did not correlate with the degree of myopia. It seems that the central cornea is not significantly involved in the process of myopic progression.

Central Corneal Thickness of Korean Patients with Glaucoma

To characterize the central corneal thickness (CCT) in Koreans and assess CCT variation in different types of glaucoma. Observational cross-sectional study. Patients previously diagnosed as primary open-angle glaucoma (POAG, n = 343), normal-tension glaucoma (NTG, n = 192), and ocular hypertension (OHT, n = 44), as well as nonglaucomatous patients (n = 224) examined in a glaucoma clinic in Korea. Participants' CCT was measured by ultrasound pachymetry. Mean CCT and its correlations with glaucoma diagnosis, age, spherical equivalent, gender, diabetes, and hypertension. Mean CCT was highest in eyes with OHT (582.1 microm, P<0.0001), lowest in NTG (537.5 microm, P<0.0001), and intermediate and similar in eyes with POAG and healthy eyes (550.7 and 553.6 microm, respectively, P = 0.289). Central corneal thickness was inversely correlated with age (r = -0.12; P<0.0001). There was no statistically significant difference in mean CCT between eyes with different gender or presence of diabetes and hypertension. Mean CCT in normal and OHT eyes was weakly correlated with refractive error (P<0.05). In Korean subjects, CCT is greatest in eyes with OHT and least in eyes with NTG.