Intradevice Repeatability and Interdevice Comparison of Two Specular Microscopy Devices in a Real-Life Setting: Tomey EM-4000 and Nidek CEM-530.

Background and Objectives: The purpose of this study was to compare two commercially available specular microscopes (Tomey EM-4000 and Nidek CEM-530) in a real-life clinical setting in terms of intra- and interdevice variability. The study was conducted on all patients seen in a clinical practice specializing in anterior segment pathologies, regardless of the purpose of their visit. Materials and Methods: In total, 112 eyes of 56 patients (age 23-85 years old) were included in the study. Each eye was measured three times with each device (for a total of six measurements), and results for central corneal thickness (CCT) and corneal endothelial cell density (ECD) were recorded. The results were then evaluated with the D'Agostino-Pearson normality test and compared with a Wilcoxon signed-rank test, t-test, ANOVA or Mann-Whitney test for intra- and interdevice variability. Results: Both specular microscopes produced very reliable reproducible intradevice results: The Tomey EM-4000 measured an ECD of 2390 ± 49.57 cells/mm2 (mean ± standard error of mean); the range was 799-3010 cells/mm2. The determined CCT was 546 ± 5.104 µm (mean ± standard error of mean [SEM]); the range was 425-615 µm. The measurements with the Nidek CEM-530 revealed an ECD of 2417 ± 0.09 cells/mm2 (mean ± SEM); the range was 505-3461 cells/mm2 (mean ± SEM). The mean CCT detected was 546.3 ± 4.937 µm (mean ± SEM); the range was 431-621 µm. The interdevice differences were statistically significant for both parameters, ECD (p = 0.0175) and CCT (p = 0.0125) (p < 0.05). Conclusions: The Nidek CEM-530 and the Tomey EM-4000 both produced reliable and reproducible results in terms of ECD and CCT. The absolute measurements were statistically significantly different for CCT and ECD for both devices; the Nidek produces slightly higher values.

Associations between endothelial cell characteristics and corneal topography findings in different stages of keratoconus.

PURPOSE: This study aimed to compare and correlate specular microscope indices and corneal topography indices in different stages of keratoconus. METHODS: Two hundred forty-six eyes of 123 participants were enrolled in the study. Corneal topography was performed using Sirius (CSO, Italy), with a rotating Scheimpflug camera and a Placido disc topographer. Corneal endothelial cell indices were assessed using a specular microscope (Nidek CEM-530, Japan). Eyes were graded as keratoconus stages 0-4 according to the Amsler-Krumeich classification. Corneal topography and endothelial cell indices were compared among the groups, and the correlations between them were analyzed. RESULTS: The mean age of the patients was 23.26 ± 6.75 years (range, 14-47 years). Forty-eight cases were male (39%) and 75 were female (61%). There were no statistically significant age (p = 0.578) or sex ratio (p = 0.529) differences between the groups. Twenty-nine eyes were included in the control group (11.78%), while 41 (16.67%) had stage 1 keratoconus, 88 (35.77%) had stage 2, and 88 (35.77%) had stage 3. Measurement was not possible in stage 4 keratoconus. No statistically significant difference was determined in specular microscopy values according to the stage of keratoconus, except for the number of analyzed cells (NUM) (p > 0.05). The lowest NUM values were observed in stages 1, 2, and 3, with values of 184.34 ± 67.62 cells/mm2, 155.07 ± 59.48 cells/mm2, and 127.06 ± 64.39 cells/mm2, respectively (p = 0.001). In the keratoconus group, weak statistically significant negative correlations were observed between NUM and SimK1, SimK2, KVf, BCVf, KVb, and BCVb, while a weak positive correlation was noted between NUM and central corneal thickness (p < 0.05). CONCLUSIONS: NUM seems to decrease, while endothelial cell density exhibits no significant changes, with the progression of keratoconus. It appears that as keratoconus index values increase, NUM may decrease in different stages of keratoconus.

Correlation between corneal endothelial layer features and age-related macular degeneration severity.

PURPOSE: This study aimed to investigate the relationship between corneal endothelial layer features and the severity of age-related macular degeneration (AMD). METHODS: The study included 119 patients, with 47 females and 72 males. Patients were categorized into four groups based on the AREDS grading system: no AMD (group 1), mild AMD (group 2), moderate AMD (group 3), and advanced AMD (group 4). Only the right eye of patients with both eyes suitable for the study was included. Corneal endothelial cell density (CD), coefficient of variation (CoV), hexagonal cell ratio (HEX), and central corneal thickness (CCT) were measured using specular microscopy (Konan Medical Inc., Nishinomiya, Japan). RESULTS: Group 1 had 40 patients, group 2 had 27 patients, and groups 3 and 4 had 26 patients each. Significant differences were observed between the mean endothelial CD, CoV, and HEX values among the groups, while no significant difference was found in CCT values (p = 0.049, p = 0.002, p = 0.004, and p = 0.883, respectively). A mild negative correlation was observed between AMD severity and CD and HEX values, while a mild positive correlation was found between AMD severity and CoV. CONCLUSION: Increasing severity of AMD may negatively impact corneal endothelial layer values.

The effect of accelerated pulsed high-fluence corneal cross-linking on corneal endothelium; a prospective specular microscopy study.

BACKGROUND: Corneal collagen cross-linking (CXL) is a procedure utilized for halting keratoconus progression with different approved protocols. The current study aimed to assess the corneal endothelial changes following the relatively new accelerated pulsed high-fluence protocol of epithelium-off corneal cross-linking for the treatment of mild to moderate keratoconus. METHODS: This prospective case series study enrolled 45 eyes of 27 patients with mild to moderate progressive keratoconus who underwent accelerated pulsed high-fluence CXL (pl-ACXL, 30 mW/ cm2 UVA at 365 nm wavelength, 8 min pulsed mode 1 s on / 1 s off with a total energy of 7.2 J/ cm2). The main outcome measures were corneal endothelial changes assessed by specular microscopy at 3 and 6 months postoperatively including endothelial cell density (ECD), coefficient of variation, percentage of hexagonal cells, average, minimum and maximum endothelial cell sizes. Demarcation line depth was assessed 1 month following surgery. RESULTS: The mean age of the studied sample was 24.89 ± 7.21. The mean preoperative ECD (2944.6 ± 247.41 cell/mm2) showed non-significant reduction at 3 and 6 months postoperatively (2931.03 ± 253.82 and 2924.7 ± 224.88 cell/mm2, respectively, P-value = 0.361). There were no significant changes in the mean coefficient of variation, percentage of hexagonal cells, average, minimum and maximum endothelial cell sizes at 3 and 6 months following pl-ACXL (P-value > 0.05). The mean demarcation line depth 1 month after pl-ACXL was 214 ± 17.43 µm. CONCLUSIONS: Corneal endothelial changes following accelerated pulsed high-fluence CXL were minimal with stability of endothelial cell count and non-significant morphological changes. TRIAL REGISTRATION: Clinicaltrials.gov: NCT04160338 (13/11/2019).

Evaluation of the corneal thickness and endothelial changes following uncomplicated phacoemulsification in diabetic and non-diabetic patients with pseudo-exfoliation syndrome by specular microscopy.

PURPOSE: To evaluate corneal endothelial cell changes following uncomplicated phacoemulsification in diabetic patients with PEX, compared with diabetic patients and non-diabetic patients with PEX. METHODS: This prospective, comparative, non-randomized cohort study included 61 eyes of 61 patients who were diagnosed as having senile cataract. Patients were divided into three groups: Group (1) included 19 eyes of patients with DM and PEX, group (2) included 22 eyes of diabetic patients, and group (3) included 20 eyes of patients with PEX. All included patients had uncomplicated phacoemulsification with IOL implantation. Patients were examined by non-contact specular microscopy (NIDEK, CEM-530, Japan), preoperatively and postoperatively at regular follow-up periods (one, three, and six months postoperatively) with analysis of the endothelial cell density, percentage of hexagonal cells, CV, and CCT. RESULTS: By the end of follow-up period, there was a statistically significant reduction in ECD and HEX with a significant increase in CV and CCT in group one (DM-PEX). In group two (DM), a statistically significant decrease in ECD and HEX with a significant increase in CCT was reported, while in group three (PEX), the only significant difference was found in the form of ECD reduction. CONCLUSION: Patients with DM and PEX had significant changes regarding ECD, CV, HEX, and CCT which were more pronounced than in patients with DM only or PEX only. More attention should be paid while operating on diabetic patients with PEX to save corneal endothelium and decrease postoperative complications. STUDY REGISTRATION NUMBER: The study was retrospectively registered (16 July 2021) on ClinicalTrials.gov (NCT04965168).

Assessment of corneal endothelial cell parameters using specular microscopy in previously infected SARS-CoV-2 patients.

PURPOSE: To examine the long-term effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on the corneal endothelium. METHODS: This was a comparative, cross-sectional study that included subjects who had recovered from SARS-CoV-2 infection for at least 6 months (group 1) and a group of age- and sex-matched controls with no prior symptomatology or documentation of SARS-CoV-2 infection (group 2). After full ophthalmological evaluation, specular microscopy was used to examine the endothelial cell parameters, including endothelial cell density, coefficient of variation, hexagonality, average area, and central corneal thickness. RESULTS: Sixty-four and 53 right eyes were included in groups 1 and 2, respectively. No statistically significant differences were detected in any of the examined specular parameters between the two groups. CONCLUSION: SARS-CoV-2 infection may have no delayed sequel on the corneal endothelium. Future prospective studies with repeated examinations in the same subjects would be useful.

Case-control study of corneal topography and specular microscopy parameters in JIA patients with and without ocular involvement.

PURPOSE: To assess corneal topography and specular microscopy values in juvenile idiopathic arthritis-related uveitis (JIA-U). METHODS: This case-control study included 30 eyes from JIA-U patients, 20 eyes from JIA patients, and 50 eyes from age- and gender-matched healthy subjects. Patients with a history of ocular diseases or intraocular surgery were excluded. Corneal topography maps (Pentacam HR) and specular microscopy images (CellChek SL) were obtained. The measurements of the groups were compared. RESULTS: Keratometric astigmatism was higher in the JIA-U group than in the control group (p = 0.040). Patients with astigmatism greater than 1.50D were more common in the JIA-U group than in the control group (p = 0.026). The JIA-U group had higher anterior and posterior elevation values than the control group (p = 0.006, p = 0.025). The density of endothelial cells, coefficient of variation, and hexagonality did not change across groups (p = 0.465, p = 0.096, p = 0.869). The total number of exacerbations and the duration of anterior chamber inflammation were both positively correlated with posterior elevation (r = 0.600, p 0.001; r = 0.583, p 0.001). The age of diagnosis was found to be negatively correlated with anterior elevation (r = -0.412, p = 0.021). CONCLUSION: Corneal astigmatism, as well as anterior and posterior elevation values, were all higher in JIA-U patients. Endothelial cell density and morphology, on the other hand, did not differ significantly between groups. Chronic inflammation's impact on stromal remodelling could explain these corneal alterations. The positive correlation between posterior elevation and the number of flares and duration of inflammation represents the importance of early diagnosis and effective treatment.

Comparison of central corneal thickness in healthy eyes using ultrasound pachymetry, non-contact specular microscopy and a high-resolution Scheimpflug camera.

PURPOSE: To compare and analyze the interchangeability in measuring central corneal thickness (CCT) using ultrasonic pachymetry (USP, PACHMATE 2, DGH, Inc, Exton, PA, USA), non-contact specular microscopy (NCSM, CEM-530, Nidek CO, LTD, Gamagori, Japan) and a high-resolution Scheimpflug Camera (Pentacam HR, OCULUS, Wetzlar, Germany). METHODS: An observational, cross-sectional study was performed recruiting 216 volunteers, for a sample size of 216 eyes with no ocular abnormalities other than refractive errors. All subjects underwent pachymetric measurements obtained by USP, NCSM and Pentacam HR. Examinations were performed by the same examiner with USP always following the noncontact examinations. RESULTS: The mean CCT (± SD) was 560.30 ± 38.80 µm, 556.76 ± 36.83 µm and 547.31 ± 35.28 µm for USP, NCSM and Pentacam HR, respectively. The Bland-Altman analysis showed that the highest concordance was found between USP and NCSM, with differences between - 13.18 µm and 20.26 µm. For the differences between measurements obtained with Pentacam HR and USP, the differences at Bland-Altman plot were between - 28.25 and 13.57 µm. The lowest concordance was found for the CCT values measured with Pentacam HR and NCSM, with differences between - 25.67 and 6.86 µm. The intraclass correlation coefficient (ICC) between all pairs of measurements was between 0.979 and 0.987, suggesting that the mean measurements were strongly correlated. CONCLUSION: Measurements obtained with all three devices had high correlation. USP and NCSM were found in good agreement and high concordance, too. The above results indicate that these two devices are interchangeable in clinical practice. Pentacam HR may be a useful alternative for measuring CCT; however, it significantly underestimates CCT and cannot be used interchangeably with the other devices that we studied.

An evaluation of corneal endothelial cell morphology in patients with thyroid-associated ophthalmopathy.

INTRODUCTION: To evaluate corneal endothelial cell morphology in patients with thyroid-associated ophthalmopathy (TAO). METHOD: Seventy-two eyes of 36 patients with TAO presenting to the ophthalmology department between January 2018 and January 2022 were included in the study. The findings were compared with 98 eyes of 49 healthy individuals. Mean endothelial cell density (ECD), coefficient of variation (CV), maximum cell area, minimum cell area, average cell area, and hexagonality ratio were obtained using non-contact specular microscopy. The thicknesses of peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC) were measured using optical coherence tomography (OCT). RESULTS: The TAO group consisted of 36 patients, 11 (30.6%) men and 25 (69.4%) women, and the control group of 49 healthy individuals, 14 (28.6%) men and 35 (71.4%). No significant differences were determined between the TAO and control groups in terms of the specular microscopy findings of mean ECD, CV, or hexagonality ratio values (p > 0,05). However, the mean Hertel values differed significantly between the two groups (p = 0.001). When the TAO group was divided into two subgroups based on patients who had previously received prednisolone therapy and those who had not, significant differences were observed in terms of mean ECD, CV, and hexagonality ratio values (p > 0.05). CONCLUSION: Comparison of patients diagnosed with active TAO and receiving prednisolone therapy and the TAO patients with inactive disease revealed lower ECD, higher CV values, and lower hexagonality ratios in the prednisolone therapy group. These findings all suggest that inflammation in patients undergoing active disease affects the corneal endothelium.

An automatic approach for cell detection and segmentation of corneal endothelium in specular microscope.

PURPOSE: Specular microscopy is an indispensable tool for clinicians seeking to monitor the corneal endothelium. Automated methods of determining endothelial cell density (ECD) are limited in their ability to analyze images of poor quality. We describe and assess an image processing algorithm to analyze corneal endothelial images. METHODS: A set of corneal endothelial images acquired with a Konan CellChek specular microscope was analyzed using three methods: flex-center, Konan Auto Tracer, and the proposed method. In this technique, the algorithm determines the region of interest, filters the image to differentiate cell boundaries from their interiors, and utilizes stochastic watershed segmentation to draw cell boundaries and assess ECD based on the masked region. We compared ECD measured by the algorithm with manual and automated results from the specular microscope. RESULTS: We analyzed a total of 303 images manually, using the Auto Tracer, and with the proposed image processing method. Relative to manual analysis across all images, the mean error was 0.04% in the proposed method (p = 0.23 for difference) whereas Auto Tracer demonstrated a bias towards overestimation, with a mean error of 5.7% (p = 2.06× 10-8). The relative mean absolute errors were 6.9% and 7.9%, respectively, for the proposed and Auto Tracer. The average time for analysis of each image using the proposed method was 2.5 s. CONCLUSION: We demonstrate a computationally efficient algorithm to analyze corneal endothelial cell density that can be implemented on devices for clinical and research use.

Diabetic retinopathy and corneal endothelial parameters: an analytical cross-sectional study.

BACKGROUND: To investigate the possible association of different pattern of diabetic retinopathy (DR) on corneal endothelium cells in type 2 diabetes mellitus patients. METHODS: In this descriptive-analytical cross-sectional study, corneal endothelium parameters including endothelial cell density (ECD), average cell size (AVG), coefficient of variation in cell size (CV), and hexagonality (Hex) were evaluated by non-contact specular microscopy. RESULTS: One hundred and thirty-four eyes of 134 diabetic patients including 77 females (57.5%) with a mean age of 61.03 ± 8.08 years were enrolled. The overall corneal parameters in diabetic patients with and without retinopathy were not significantly different (P > 0.05). There is a significant relationship between CV and the duration of the disease with age variable control (B = 0.369, p-value < 0.001). CONCLUSIONS: Corneal endothelial parameters were not associated with DM in patients without and with DR. There is a significant relationship between CV and the duration of the disease with age variable control.

Evaluation of corneal endothelial cell morphology by specular microscopy in patients with acute anterior uveitis.

PURPOSE: To determine the structure and morphology of corneal endothelial cell layer in patients with acute anterior uveitis. METHODS: Thirty-four eyes of 34 acute anterior uveitis patients and 34 eyes of 34 healthy subjects were included. Mean cell density, coefficient of variation, maximum cell area, minimum cell area, average cell area and hexagonality ratio values were evaluated by non-contact specular microscopy. Parameters recorded in both groups were compared. RESULTS: The mean maximum cell area was 1054,44 ± 251,14 µm2, minimum cell area was 152.29 ± 53.65 µm2 and average cell area was 386.91 ± 41.73 µm2 in acute anterior uveitis group and the mean maximum cell area was 1057.65 ± 261.23 µm2, minimum cell area was 147.26 ± 20.45 µm2 and average cell area was 383.53 ± 43.12 µm2 in the control group. There were no significant differences between the two groups in terms of maximum, minimum and average cell area (respectively, p = 0.080, p = 0.72, p = 0.62, p = 0.67). The mean cell density was 2607.74 ± 277.63 cells/ µm2 in acute anterior uveitis group and 2669.35 ± 265.22 cells/µm2 in the control group. (p = 0.358). In acute anterior uveitis group the mean coefficient of variation was 31.68 ± 8.16, hexagonality ratio was 63.85 ± 11.14 and mean central corneal thickness was 571.47 ± 55.99 µm; in control group the mean coefficient of variation was 25.29 ± 3.00, mean hexagonality ratio was 72.6 ± 4.80% and mean central corneal thickness was 534.82 ± 33.84 µm. Statistically significant differences were seen between the two groups (respectively, P = 0,00, P = 0,00, P = 0.02). CONCLUSION: The mean central corneal thickness and coefficient of variation values were found higher, and the hexagonality ratio was found lower in acute anterior uveitis group. Our findings suggest that intraocular inflammation in anterior chamber negatively affects the endothelial function in patients with acute anterior uveitis.

Demographic profile and clinical course of Fuchs endothelial corneal dystrophy in Mexican patients.

PURPOSE: To describe the demographic characteristics and clinical course of Fuchs endothelial corneal dystrophy (FECD) in a Mexican-mestizo population. METHODS: A retrospective observational and longitudinal study was performed in consecutive patients with the clinical diagnosis of Fuchs endothelial corneal dystrophy seen at our institution. Initial and last follow-up best-corrected visual acuity, slit-lamp findings, and specular microscopy endothelial morphometric parameters were analyzed. RESULTS: One hundred and two eyes belonging to 51 patients were included in the analysis. Median age at the time of diagnosis was 69 years (range, 25-87 years) with a female-to-male ratio of 3.3:1. Visual loss (40%) followed by glare (13.3%) and fluctuating matutine vision loss (13.3%) was the most common complaints at presentation. Regarding FECD staging, 65 (63.7%) were classified as stage-I FECD, 21 (20.6%) stage-II, and 15 (14.7%) as stage-III. A high percentage of eyes (44.1%) presented visual impairment ( ≤ 20/50) at presentation, and the presence of isolated corneal guttata was the most common stage of presentation (64%) at slit-lamp examination. While fifty-nine (57.8%) eyes did not require any medical or surgical management, 17 (16.7%) eyes were managed with hypertonic saline eyedrops alone or in combination with bandage contact lens, and 18 (17.6%) required corneal transplantation. Penetrating keratoplasty alone (8 eyes, 44.4%), or in combination with cataract extraction and intraocular lens implantation (3 eyes, 16.7%), was the most frequent surgical technique performed. CONCLUSION: Demographical characteristics of Fuchs dystrophy regarding age at presentation, gender distribution, and clinical stage at the time of diagnosis did not differ significantly from other international reports. Almost 20% of these patients will require keratoplasty during the disease, emphasizing the need for safer and more reproducible keratoplasty techniques.

Overestimation of corneal endothelial cell density by automated method in glaucomatous eyes with impaired corneal endothelial cells.

PURPOSE: To determine between-method differences in corneal endothelial cell parameters using center and automated methods of non-contact specular microscopy (CellCheck software of Konan, Inc.) in glaucomatous eyes. METHODS: We analyzed the central corneal endothelial cell density (ECD) of 245 glaucomatous eyes using center (ECD-Ce) and automated methods (ECD-Au). Based on the ECD-Ce, we allocated subjects to Groups 1 to 10 (at 250 cells/mm2 intervals) and evaluated the ECD, coefficient of variation in cell area (CV), and percentage of hexagonal cells (HEX). RESULTS: There was a close correlation (r = 0.91) between the ECD values measured using both methods. However, ECD-Au were significantly higher than those measured by the center method when ECD-Ce was less than 2500 (in Groups 1 to 8; P < 0.001 to P = 0.006). The regression equation of (ECD-Au-ECD-Ce) = 1028-0.397*ECD-Ce shows greater deviation in eyes with lower ECD, and this difference became 0 when ECD -Ce was 2593 cells/mm2. None of the 44 subjects with an ECD-Ce of < 1000 cells/mm2 recorded an ECD-Au < 1000 cells/mm2. Compared with the center method, the automated method had higher and lower median CV and HEX values, respectively (P < 0.001). The between-method differences in both CV and HEX were negatively correlated with ECD-Ce (r = -0.49, P < 0.001 and r = -0.25, P < 0.001, respectively). CONCLUSION: The automated method of the CellCheck software overestimates ECD in eyes with lower ECD values and may overlook risk of corneal decompensation.

Central corneal thickness measurements in phakic, pseudophakic, and aphakic children with ultrasound pachymetry and different non-contact devices.

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.

[Laser-induced damage to the cornea after YAG laser surgery of anterior segment structures]. / Lazerindutsirovannye povrezhdeniya rogovitsy posle YAG-lazernykh vmeshatel'stv na strukturakh perednego segmenta glaza.

Laser photodestruction (LPD) of tissues is the basis of modern laser reconstructive surgery in ophthalmology. The most common laser technologies based on LPD mechanisms include YAG laser capsulotomy (discission) (LD) of secondary cataract and YAG laser iridectomy (LIE) for glaucoma. Laser reconstructive interventions for secondary cataract, as well as LIE, have a number of advantages over traditional surgery, but at the same time are associated with the risk of complications, including in the cornea. Corneal endothelium is the most susceptible to laser damage, while Descemet's membrane and corneal stroma are injured less often. This review describes cases of iatrogenic perforation and purulent inflammation of the cornea. In the long-term, laser interventions can lead to bullous keratopathy and corneal graft rejection. At this time, the most popular and available among the methods for assessing the cornea after YAG laser interventions is the method of specular microscopy. Ultrasound biomicroscopy is used less commonly. The modern method of corneal confocal microscopy is practically not used for this purpose, and taking into account the risks of developing laser-induced injuries, it indicates its relevance and the need for further research.

Examination of the effects of COVID 19 on corneal endothelium.

PURPOSE: To demonstrate the effects of the disease on the corneal endothelium in individuals recovering from COVID-19 through specular microscopy. METHODS: Eighty individuals recovering from COVID-19 (group 1) and 72 healthy controls (group 2) were included in this prospective study. After examining visual acuity, refractive defect detection, anterior and posterior segment examinations, and specular microscopy measurements were calculated from images with at least 100 cells. The mean cell density (CD), mean coefficient of variation (CV), mean hexagonal cell percentage, mean cell area (AVG), and central corneal thickness (CCT) were evaluated. RESULTS: The mean time from diagnosis of the disease in group 1 was 54.25 ± 6.36 days. The mean time elapsed since the PCR test became negative was 38.45 ± 6.87 days. Only four were treated in the hospital. Specular microscopy data showed that the CD was 2713.56 ± 246.25 and 2845.80 ± 299.27 in groups 1 and 2, respectively (p = 0.003). The CV values were 42.92 ± 6.79 and 40.16 ± 5.97, respectively (p = 0.009). The hexagonality were 46.51 ± 7.35 and 49.12 ± 6.87, respectively (p = 0.024). The AVG was 371.60 ± 34.64 and 353.16 ± 35.29, respectively (p = 0.007). The CCT values were 553.00 ± 73.2, and 526.84 ± 33.57, respectively (p = 0.005). CONCLUSION: A decrease in the number of endothelial cells and hexagonal cells (polymorphism) as well as an increase in the cell area change coefficient (polymegatism) and the average cell area were observed from corneal specular microscopic examination of individuals recovering from COVID-19 in the early period of the disease. These results may be important in understanding the systemic effects of the disease.

Corneal endothelial cells changes in different stages of Keratoconus: a multi-Centre clinical study.

PURPOSE: To assess the corneal endothelial cells morphology and count in keratoconus patients and their correlation with different stages of keratoconus. METHODS: Prospective non randomized multi-centric clinical study included 150 eyes of 150 keratoconus patients. Four centers in Egypt participated in this study included: Departments of Ophthalmology in Alexandria University, Tanta University and Port Said University and Alex I-Care hospital. Pentacam (Wavelight Oculyzer II) and specular microscopy (Tomey EM-3000) were done to all eyes. Keratoconic eyes were classified according to Amsler classification into stage 1, 2 and 3. Stage 1 included 99 eyes, stage 2 included 32 eyes & stage 3 included 19 eyes. RESULTS: The mean age of keratoconus patients was 24.07 ± 6.154 years. Forty five cases were males (30%) and 105 cases were females (70%). There was statistically significant difference in endothelial cell density (p < 0.001) and coefficient of variation (p = 0.012) between different stages of keratoconus eyes. Regarding cell surface area, there was statistically significant difference in cell surface area between different stages of keratoconus eyes (p < 0.001). In addition, for cell morphology, there was statistically significant difference between different stages of keratoconus eyes (p < 0.001). CONCLUSIONS: Qualitative and quantitative structural changes were seen in endothelial cells of keratoconus eyes by using specular microscopy. For stages 1 and 2, keratoconus may not affect the corneal endothelim significantly. The endothelium in stage 3 shows significant changes regarding polymegathism and pleomorphism.

Profile of central corneal thickness and corneal endothelial cell morpho-density of in healthy Congolese eyes.

PURPOSE: To determine the pachymetric and corneal endothelial cell morphometric features and their relationship to ocular and systemic factors in healthy Congolese subjects. METHODS: Non-contact specular microscopy was used in 278 healthy eyes (278 subjects) to measure central corneal thickness (CCT), corneal endothelial cell density (CECD) along with cell size, coefficient of variation (CV) in cell size, and hexagonality (HEX). The lower and upper reference limits and average values for each parameter were determined. Correlation and association of average values with anthropo-demographic and clinical variables were assessed. RESULTS: The mean age was 38.9 ± 17.2 years (10.9-80.7 years). Average values were 504.2 ± 30.7 µm (CCT), 2907.1 ± 290.9 cells/mm2 (CECD), 348.5 ± 38.4 µm2 (cell size), 32.9 ± 3.6% (CV), and 51.8 ± 7.2% (HEX). CCT was 504.9 ± 33.6 µm in men and 503.6 ± 28.3 µm in women (p = .73); values for CECD were 2917.1 ± 253.5 cells/mm2 and 2899.2 ± 317.8 cells/mm2 (p = 0.61), respectively. Lower and upper reference limits were 449.6 µm and 566.0 µm for CCT, and 2165.3 cells/mm2 and 3414.4 cells/mm2 for CECD, respectively. CCT correlated with body mass index (BMI), (r = - 0.12, P = 0.04). CECD decreased with age (r = - 0.49, P < 0.001), BMI (r = - 0.20, P = 0.001), intraocular pressure (r = - 0.13, P = 0.029) and ocular perfusion pressure (r = - 0.28, P = 0.028). CECD decayed by 8.3 cells/mm2 or 0.30% per year of age and CCT decreased by 0.72 µm per kg/m2. CONCLUSIONS: Mean central cornea was thinner, CECD higher, and references limits lower than reported in other African populations. The CCT and CECD normative values reported herein will be useful for both clinical and research purposes in this population.

Evaluation of corneal safety in systemic lupus erythematosus patients undergoing long-term hydroxychloroquine treatment.

PURPOSE: The aim of this study was to examine the effects of long-term use of hydroxychloroquine (HQ) on the pachymetric, aberrometric, and densitometric values of the cornea and corneal endothelium in lupus patients. METHOD: Twenty-two eyes (study group) of 22 patients using HQ for treatment of lupus and 25 eyes (control group) of 25 healthy individuals were included in this prospective study. A specular microscopy was used to measure corneal endothelial cell density (ECD), percentage of hexagonal cells (HEX%), coefficient of variation of the cell size (CV). Then, a Pentacam® HR corneal tomography system was used to measure central corneal thickness (CCT), corneal aberrometry values in 6-mm pupil diameters and corneal densitometry values in 6-mm corneal zones (0-2 mm and 2-6 mm). RESULTS: While ECD was significantly lower in the study group than in the control group (p = 0.034), CCT was significantly higher in the study group (p = 0.032). The higher-order aberrations values and the anterior corneal densitometry values in the 0-2 mm and 2-6 mm corneal zones in the study group were found to be significantly higher than the control group (p = 0.021, p = 0.007 and p = 0.013). CONCLUSION: Prolonged use of HQ may cause some changes in the cornea. In the follow-up of these cases, detailed examination of the cornea as well as the macula may be important for the protection of corneal health.