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On the reliability (repeatability) of single pachymetry measures taken with specular microscope-based assessments of the human corneal endothelium
摘要： Purpose: To assess agreement between 3 measures of central corneal thickness (CCT) taken over a few minutes from nominally normal eyes with a non-contact specular microscope. Methods: 100 eyes from 100 healthy adults (with an average age of 22 y) were assessed using the Topcon 3000 P instrument to obtain a high quality image of the endothelium and pachymetry. Results: The group mean CCT values from the 1st, 2nd and 3rd measures were 0.519, 0.520 and 0.520 mm, but the sets of values could di?er by between – 0.020 mm and + 0.029 mm, i.e. between - 4.0 and + 5.6% of the average values. Paired comparisons (e.g. 2nd vs. 1st set) indicated limits of agreement (LoA) to be between - 0.020 and + 0.020 mm of the averaged value. Across the 3 measures, the averaged SD was 0.005 mm to give an estimate of the intra-subject variability (as the coe?cient of variation, COV) of 0.91% (range 0 to 2.3%). The variability in the pachymetry measures was not predictably related to the averaged values of CCT (r = 0.022) or self-reported refractive error of the subjects (r = 0.012). Some repeat pachymetry assessments obviously in-cluded the same region of the endothelium. Conclusions: Single pachymetry measures with a non-contact specular microscope are only likely to be able to generate CCT estimates within +/? 4% of the expected average values. This repeatability is comparable to single image estimates of endothelial cell density and therefore acceptable in most cases.
关键词： Cornea,Pachymetry,Human,Repeat measures,Central corneal thickness
更新于2025-09-23 15:21:21
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Reproducibility of Central Corneal Thickness Measurements in Normal Eyes Using the Zeiss Cirrus 5000 HD-OCT and Pentacam HR
摘要： Objectives: To determine the repeatability and reproducibility of Central Corneal Thickness (CCT) measurements using two different anterior segment imaging modalities, including those obtained with the new anterior segment lens attachments for the Cirrus 5000 HD-OCT. Methods: A total of 32 eyes from 16 normal volunteers (8 male, 8 female) were enrolled in this prospective study. CCT was measured by the same examiner using the Cirrus 5000 HD-OCT and Pentacam HR. The results of CCT obtained by each method were averaged and compared using t-test analysis. The agreement between the measurement methods was evaluated. Coefficient of Repeatability (CoR) and Intra-Class Correlation Coefficient (ICC) were computed. Results: The mean measurements taken with the Cirrus OCT anterior chamber lens (CCTAC), HD cornea lens (CCTHDC) and pachymetry scans (CCTPach) were 545.35 ± 31.02, 537.87 ± 26.82, and 532.04 ± 29.82 μm, respectively. The mean CCT obtained with the Pentacam (CCTPent) was 545.51 ± 30.71 μm. CCTPent were significantly higher than CCTHDC and CCTPach (p< 0.0001). In contrast, the CCTPent and CCTAC were similar (p=0.87). CCT, as evaluated by the two different instruments, showed excellent correlation (r > 0.98, p< 0.0001) with an ICC > 0.99 (95% CI, 0.97 – 0.99). CoR was the highest for CCTPach (3.7 ± 1.4, 95% CI (3.0- 4.6)). Conclusion: CCT measurements from the Cirrus OCT using the new anterior segment lens attachments and the Pentacam HR are highly correlated. This should allow the use of a standardized correction factor if necessary to inter-relate the measurements between the two devices.
关键词： Imaging,Central corneal thickness,Cornea,Optical coherency tomography,Scheimpflug technology,Pachymetry
更新于2025-09-23 15:21:01
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Effectiveness of intraoperative intraocular lens use on improving surgical safety for dense cataract phacoemulsification: a randomized controlled trial
摘要： We designed this study to assess if surgical safety can be improved by intraoperative use of intraocular lens (IOL) for cataract phacoemulsification. We performed phacoemulsification cataract removal on 401 patients. We randomly assigned these patients into three groups: the standard setting (Group I, n = 134), with reduced vacuum and flow rate (Group II, n = 137), and with IOL insertion before the last quadrant was emulsified with standard setting (Group III, n = 130). The primary outcomes included the risk of posterior capsular rupture (PCR), ultrasound time, energy, and complications. The secondary outcomes included central corneal thickness (CCT), CCT changes, endothelial cells (ETC) counting, ETC loss, and the best corrected distance visual acuity (BCVA) measured on day 1, day 7 and day 30. If PCR occurred, we emulsified the residual lens materials after insertion of IOL and clean of the prolapsed vitreous. We found that the risk of PCR in Group III (0/130) was lower than Group I (9/134, corrected relative risk (RR) = 18.44, 95% CI: 1.08–313.56) and Group II (3/137, corrected RR = 6.64, 95% CI: 0.35–27.41). Group III showed better BCVA on day 1 and 7, less ECC loss on day 7 and 30, and less CCT increase on day 1 and 7. No cases converted to extracapsular cataract extraction. No residual lens materials misdirected into vitreous cavity. Intraoperative use of IOL can improve surgical safety for dense cataract phacoemulsification.
关键词： cataract phacoemulsification,intraocular lens,surgical safety,posterior capsular rupture,ultrasound time,endothelial cells loss,central corneal thickness
更新于2025-09-19 17:13:59
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A comparison of NCT, Goldman application tonometry values with and without fluorescein
摘要： Purpose: The aim of the study was to statistically compare intraocular pressure (IOP) values measured using noncontact tonometer (NCT), Goldmann applanation tonometry (GAT) with fluorescein (fGAT), and GAT without fluorescein (nGAT). The study was also performed to test whether the values obtained using each technique change in accordance with the central corneal thickness (CCT) and refractive and keratometric values. Study design: This study was a prospective study of 188 eyes of 94 healthy volunteers. Methods: IOP was measured using fGAT, nGAT and NCT. CCT, refractive values, and keratometric values were measured, and the correlations and differences in the IOP for each tonometer were investigated. Results: The mean IOP values obtained with the NCT, nGAT, and fGAT were 17.5±3.7, 12.3±2.7, and 12.5±2 mmHg. The mean CCT was 538.2±34.4 μm, the mean refractive value was 0.9±1.2 D, and the mean keratometric value was 43.5±1.5 D. NCT was positively correlated with fGAT and GAT values and was significantly higher than both the values. There were no differences between fGAT and GAT values. No correlation was observed between the CCT and keratometric and refractive values and the difference between NCT and nGAT or fGAT. Conclusion: Differences in the measurements obtained using nGAT and fGAT were insignificant (P.0.05). Both values were positively correlated with NCT measurements (r =0.354, P,0.05) and were independent of CCT, keratometry, and refraction values. nGAT appears to be suitable for use in routine clinic practice.
关键词： central corneal thickness,Goldmann applanation tonometry,intraocular pressure,refractive value,noncontact tonometry,fluorescein
更新于2025-09-09 09:28:46
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Comparison of Anterior Segment Measurements between Scheimpflug Camera and New Module of Optical Coherence Tomography
摘要： Purpose: We compared the anterior segment measurements using a Scheimpflug camera (Pentacam? [Oculus Inc., Wetzlar, Germany]) and a new anterior segment module of optical coherence tomography (Cirrus HD-OCT 5000? [Carl Zeiss Meditec, Dublin, CA, USA]). Methods: Anterior segment measurements were evaluated in 47 eyes of 26 patients who visited for the purpose of cataract surgery. Measurements of the central corneal thickness (CCT), anterior chamber depth (ACD), anterior chamber angle (ACA; nasal and temporal side), and angle to angle distance (ATA) were compared between the Pentacam? and the new anterior segment module of the Cirrus HD-OCT 5000?. Results: The mean CCTs measured by the Pentacam? and the new anterior segment module of the Cirrus HD-OCT 5000? were 561.68 ± 31.35 μm and 559.04 ± 36.43 μm, respectively. There was no statistically significant difference (p = 0.387) and high correlations in the results using the two methods (r = 0.824, p < 0.001). The mean ACD measurements using the Pentacam? and Cirrus HD-OCT 5000? were 2.70 ± 0.44 mm and 2.68 ± 0.42 mm, respectively. The measurements were strongly correlated (r = 0.981, p < 0.001) without a statistically significant difference (p = 0.091). The measurements of ACA (nasal and temporal side) and ATA did not differ significantly different between the two methods (p = 0.109, p = 0.153, p = 0.322, respectively). High correlations were observed between the two methods (r = 0.944, r = 0.951, r = 0.955, respectively; p < 0.001 in all groups). Conclusions: There was no significant difference between the CCT, ACD, ACA, and ATA measured by the Pentacam? and the new anterior segment module of the Cirrus HD-OCT 5000? in adult patients. However, there was a low degree of agreement for the CCT. The measurements of ACD, ACA, and ATA can therefore be considered interchangeable when used clinically.
关键词： Pentacam?,Anterior chamber depth,Cirrus HD-OCT?,Anterior chamber angle,Central corneal thickness
更新于2025-09-09 09:28:46