A Study in the Measurement of Corneal Endothelial Cell Density Using the Specular Microscope (original) (raw)
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A comparison of three methods for the measurement of corneal thickness
Investigative ophthalmology & visual science, 1979
Four subjects who had never worn contact lenses underwent measurement of their corneal thickness by each of three measurement methods: Haag-Streit pachometer with/and without Mishima-Hedby attachment and the Syber specular microscope. Data were collected on three separate sessions, and at each session triplicate measurement trials were made for each method. The resulting 108 measurements were analyzed statistically. Significant differences were found among the measurement methods. Two of the methods were found to be consistent from session to session. In addition, the specular microscope was found to be the most precise method within a session. It was concluded that the specular microscope, which highly trained technicians can utilize to make the measurements, offers a valuable alternative to the measurement of corneal thickness in long-term prospective studies.
Reliability of a Video-Based Noncontact Specular Microscope for Assessing the Corneal Endothelium
Cornea, 2007
Purpose: To assess the within-and between-examiner reliability of corneal endothelial cell density (ECD) measurements with 2 noncontact specular microscopes: a video-based system (SeaEagle) and a photographic system (Noncon Robo). Methods: In 57 eyes of 57 subjects, 47 healthy subjects and 10 patients with corneal disease, ECD was measured in the center and at 4 paracentral areas with the video-based system (SeaEagle) and in the center with a photographic system (Noncon Robo). For the betweenexaminer reliability, a second examiner measured the central ECD with the SeaEagle device in 12 healthy subjects. The video-based system was also used to evaluate the agreement between the automated and the manually corrected (semiautomated) modes of repeated measurements. Results: For central ECD in all eyes, the test-retest reliability assessed by the intraclass correlation coefficient was 0.77, 0.99, and 0.91 for the automated SeaEagle, semiautomated SeaEagle, and Noncon Robo, respectively. Correlation was poor to good between the 3 measurement methods (range, 0.61-0.84). For between-examiner reliability, the upper (lower) limits of agreement were 200 (2384) and 149 (292) cell/mm 2 for the automated and semiautomated SeaEagle, respectively. Conclusions: The best reliability of repeated measurements was found for the semiautomated SeaEagle. However, the semiautomated method showed significantly higher ECD values than the Noncon Robo, and this difference was highly dependent on ECD. Thus, we suggest that these methods should not be used interchangeably. The fully automated mode may need a further refinement of the cell detection algorithm.
A Population Study of the Normal Cornea using an in Vivo, Slit-Scanning Confocal Microscope
Optometry and Vision Science, 2001
Purpose. To document qualitative and quantitative changes in the normal, healthy human cornea with age using the confocal microscope. Methods. The central corneas of 120 subjects (mean age, 41 years; range, 11 to 80 years) were examined using an in vivo slit-scanning real-time confocal microscope. Images of the corneal stroma and endothelium from both eyes of each subject were semiautomatically analyzed in an observer-masked, randomized manner. Results. Anterior keratocyte density, posterior keratocyte density, and endothelial cell density were shown to be unaffected by the sex of the subject with p values of 0.46, 0.55, 0.50, respectively (multivariate analysis of variance). No statistically significant difference was detected between right and left eyes for all corneal layers examined. The anterior keratocyte density, posterior keratocyte density, and endothelial cell density decreased at a rate of 0.48, 0.22, and 0.33% per year, respectively. A positive correlation was found between the coefficient of cell variation and age. Conclusions. This data constitutes essential normative data that can be used as a control in further research into abnormal corneal conditions.
Influence of Cataract Surgery on Corneal Endothelial Cell Density Estimation
Cornea, 2005
To assess the effect of cataract surgery on semiautomated human corneal endothelial cell density (ECD) estimation using noncontact specular microscopy. Methods: In this prospective clinical study, 62 consecutive patients undergoing cataract surgery were studied. To evaluate possible variations of accuracy and agreement under clinical circumstances, the corneal ECD was determined before and after cataract surgery. The parameter ECD (cells/mm 2) in the central and paracentral cornea was consecutively determined with 2 algorithms available in a noncontact specular microscope [fixed-frame method (FFM) and automatic center method (ACM)]. The postoperative evaluation was performed at 1 day, after 4 weeks, and after 6 months. The accuracy, the relative error, and the 95% limits of agreement (LoA) were determined for both counting methods. Results: The overall group-averaged accuracy was −19.4 cells/mm 2 (0.86%) centrally and −17.3 cells/mm 2 (0.76%) paracentrally. The LoA (95% CI) were within 234 cells/mm 2 (10.4%) and 250 cells/mm 2 (10.9%), respectively. After cataract surgery, a slight decrease in accuracy was noted in the central (2.09%) and paracentral areas (1.76%). The relative error increased from 3.66% to 6.02% centrally and from 4.96% to 6.55% paracentrally. The LoA (95% CI) increased from ±194 cells/mm 2 to ±304 cells/mm 2 centrally and from ±275 cells/mm 2 to ±322 cells/mm 2 paracentrally. In the later postoperative period, endothelial stabilization improved the accuracy and agreement in ECD estimation. Conclusions: The estimation of ECD after cataract surgery employing current algorithms was achieved with a clinically acceptable level of accuracy and agreement. However, the analysis of images in the early postoperative period as well as paracentral corneal areas revealed larger variabilities. This revealed that the FFM and ACM counting methods cannot be used interchangeably under all circumstances. The ACM seemed preferable when only low-quality images were available and permitted determination of additional qualitative endothelial cell parameters.
Asia-Pacific Journal of Ophthalmology, 2019
Purpose: The aim of this study was to compare the intraobserver repeatability and agreement of central corneal thickness (CCT) measurements by 2 commonly available instruments, Zeiss IOL Master 700 (SS-OCT-based optical biometry device) and Tomey corneal specular microscope EM-3000 (Noncontact specular microscopy). Design: Retrospective study. Methods: This is a retrospective analysis of data from routine clinical practice in which preoperative CCT measurements of 105 patients scheduled for cataract surgery were analyzed. Two consecutive CCT measurements were measured using Zeiss IOL Master 700 and Tomey corneal specular microscope EM-3000 by the same examiner. The repeatability of CCT measurements was analyzed by mean intraobserver difference, coefficient of repeatability (CR), and intraclass correlation. The agreement between the 2 methods was analyzed by mean difference and limits of agreement (LoA) using the Bland-Altman method. Results: The mean absolute intraobserver differenc...
Comparison of 4 specular microscopes in healthy eyes and eyes with cornea guttata or corneal grafts
Cornea, 2015
The aim of this study was to compare 4 noncontact specular microscopes for the assessment of the corneal endothelium in a heterogeneous sample of eyes. This prospective study included 22 healthy eyes, 16 eyes with cornea guttata and 31 eyes that had undergone penetrating keratoplasty or Descemet stripping automated endothelial keratoplasty. Corneal endothelial cell parameters of all eyes were assessed with the CellChek XL (Konan Medical, Hyogo, Japan), Perseus (Bon Optic, Lübeck, Germany), EM-3000 (Tomey, Nagoya, Japan), and CEM-530 (Nidek Co, Ltd, Gamagori, Japan) in a randomized order. Bland-Altman plots of interdevice agreement were produced. The time taken for data entry, scanning, and automated image analysis was recorded, and instrument repeatability was analyzed. The mean age was 61 ± 19 years (range, 24-88). The measurement success rate was 100% in healthy corneas, ranged between 64.5% and 93.5% in eyes with corneal grafts, and between 0% and 18.8% in eyes with cornea guttat...
The effects of corneal parameters on the assessment of endothelial cell density in the elderly eye
British Journal of Ophthalmology, 2004
Background: The possible impact of corneal thickness, curvature, and size on the measurement of endothelial cell density (ECD) has largely been ignored in the normal eye. The aim of this study was to investigate the possible impact of the main corneal parameters on the analysis of ECD values at the central, superior, and temporal parts of the corneal surface. Methods: All 75 participants (52 females, 23 males) were assessed as part of a pre-cataract surgery investigation. The mean age was 75.7 (SD 10.9) years. Confocal microscopy was used to measure ECD and the percentage of six sided cells at the central, superior, and temporal parts of the cornea. The Orbscan II topography system was used to measure corneal thickness, topography, and horizontal corneal diameter. Results: The mean central ECD measured was 2488 (SD 301) cells/mm 2 , compared with 2525 (SD 505) cells/mm 2 in the temporal cornea and 2639 (SD 398) cells/mm 2 in the superior cornea. The regional differences in ECD were not significant (p.0.14). The central ECD was significantly correlated to the central (mean 0.593 (SD 0.039) mm, p = 0.021) as well as the temporal (0.628 (SD 0.039) mm, p,0.001) and the superior corneal thickness (SD 0.644 (SD 0.048) mm, p = 0.018). The mean corneal curvature at the centre (7.7 (SD 0.34) mm, p = 0.002) as well as 3 and 5 mm from the apex was significantly related to ECD (p = 0.008 and p = 0.009, respectively). Conclusions: The study suggests that in an older population, lower ECD values would be expected in thinner and/or steeper corneas.
Measurement of corneal thickness using Pentacam HR versus Nidek CEM-530 specular microscopy
Journal of International Medical Research
Objective To compare corneal thickness (CT) measurements using the CEM-530 (Nidal, Gamagori, Japan) and Pentacam HR (Oculus, Wetzlar, Germany). Methods The CT of 209 healthy subjects (209 right eyes) aged 24 to 89 years (71.35 ± 10.72 years) was measured at the corneal apex (CA), pupil center (PC), and thinnest point (TP) with the Pentacam HR and at the corneal center with the CEM-530 in random order at the same time of day. Results A good correlation but statistically significant difference was found between the CEM-530 and Pentacam HR measurements at the CA (6.10 ± 8.12 µm, R2 = 0.8947), PC (7.46 ± 8.57 µm, R2 = 0.8826), and TP (12.44 ± 10.04 µm, R2 = 0.8392). Comparison of the two devices produced the following regression formulas: y = 0.8859x + 57.644 for the CA, y = 0.8852x +56.657 for the PC, and y = 0.8557x + 68.148 for the TP, where x is the CT obtained with the CEM-530 and y is that obtained with the Pentacam HR. Conclusions These findings indicate that the CEM-530 produces...