Posterior Stromal Keratocyte Density Research Articles

Corneal Cellular and Neuroinflammatory Changes After SARS-CoV-2 Infection.

The purpose of this study was to evaluate corneal cellular and ultrastructural changes and to quantify the neuroinflammatory process in patients after mild severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Thirty patients after SARS-CoV-2 infection and 41 age-matched controls were examined. All subjects underwent in vivo confocal microscopy of the corneal cell layers and subbasal nerve fibers with the Heidelberg Retina Tomograph II. Semiautomated analysis of basal epithelial, anterior and posterior stromal keratocyte, and endothelial cell density was performed. Dendritic cell (DC) density and area were also calculated, and subbasal nerve plexus morphology was analyzed. The posterior stromal keratocyte density was significantly lower in patients after SARS-CoV-2 infection ( P = 0.0006). DC density in the central cornea was significantly higher in patients after SARS-CoV-2 infection ( P = 0.0004). There was a significant difference in the DC area between the 2 groups ( P < 0.0001). Significantly altered subbasal nerve fiber morphology was detected in patients after SARS-CoV-2 infection compared with healthy volunteers ( P < 0.05). Corneal cellular and ultrastructural changes demonstrated in this study suggest neuroinflammatory consequences of COVID-19 in the cornea in the absence of ophthalmoscopic alterations.

Keratocyte Density Is Reduced and Related to Corneal Nerve Damage in Diabetic Neuropathy.

The purpose of this study was to assess the relationship between corneal keratocyte density (KD) and corneal nerve damage in patients with and without diabetic peripheral neuropathy. Eighty-six patients with type 1 and type 2 diabetes and 21 age-matched control subjects underwent assessment of the neuropathy disability score, quantitative sensory testing, electrophysiology, and corneal confocal microscopy and were divided into those without (DN-) (n = 22) and with (DN+) (n = 64) diabetic neuropathy. Corneal sub-basal nerve parameters and KD in the anterior, mid, and posterior stroma were quantified. Anterior, mid, and posterior stromal KD were significantly reduced in DN- (P = 0.02, P = 0.009, P = 0.01, respectively) and DN+ (all P < 0.0001) subjects compared to controls. Corneal nerve branch density (CNBD) (P < 0.0001, P < 0.0001) and corneal nerve fiber length (CNFL) (P = 0.03, P < 0.0001) were significantly reduced in DN- and DN+ subjects, respectively, and corneal nerve fiber density (CNFD) (P < 0.0001) was significantly reduced only in DN+ subjects compared to controls. Anterior, mid, and posterior stromal KD correlated significantly with CNFD (P = 0.008, P = 0.005, P = 0.01), CNBD (P = 0.01, P = 0.006, P = 0.001), and CNFL (P = 0.04, P = 0.008, P = 0.003), respectively. This study demonstrates a reduction in anterior, mid, and posterior KD, which is associated with corneal sub-basal plexus nerve damage in patients with diabetes.

Effects of contact lens wearing on keratoconus: a confocal microscopy observation.

To evaluate the corneal cell morphology of new keratoconus patients wearing two different types of rigid gas-permeable (RGP) contact lenses for 1y. Thirty nine eyes of 39 new keratoconus patients were selected and randomly fitted with two types of RGP contact lenses. Group 1 had 21 eyes with regular rigid gas-permeable (RRGP) contact lens and rest 18 eyes were in group 2 with specially designed rigid gas-permeable (SRGP) contact lens. Corneal cell morphology was evaluated using a slit scanning confocal microscope at no-lens wear and after 1y of contact lens wearing. After 1y of contact lens wearing in group 1, the mean anterior and posterior stromal keratocyte density were significantly less (P=0.006 and P=0.001, respectively) compared to no-lens wear. The mean cell area of anterior and posterior stromal keratocyte were also significantly different (P=0.005 and P=0.001) from no-lens wear. The anterior and posterior stromal haze increased by 18.74% and 23.81%, respectively after 1y of contact lens wearing. Whereas in group 2, statistically significant changes were observed only in cell density & area of anterior stroma (P=0.001 and P=0.001, respectively) after 1y. While, level of anterior and posterior stromal haze increased by 16.67% and 11.11% after 1y of contact lens wearing. Polymegathism and pleomorphism also increased after 1y of contact lens wearing in both the contact lens groups. Confocal microscopy observation shows the significant alterations in corneal cell morphology of keratoconic corneas wearing contact lenses especially in group 1. The type of contact lens must be carefully selected to minimize changes in corneal cell morphology.

Corneal Cell Morphology in Keratoconus: A Confocal Microscopic Observation.

To evaluate corneal cell morphology in patients with keratoconus using an in vivo slit scanning confocal microscope. A cross-sectional study was conducted to evaluate the corneal cell morphology of 47 keratoconus patients and 32 healthy eyes without any ocular disease. New keratoconus patients with different disease severities and without any other ocular co-morbidity were recruited from the ophthalmology department of a public hospital in Malaysia from June 2013 to May 2014. Corneal cell morphology was evaluated using an in vivo slit-scanning confocal microscope. Qualitative and quantitative data were analysed using a grading scale and the Nidek Advanced Visual Information System software, respectively. The corneal cell morphology of patients with keratoconus was significantly different from that of healthy eyes except in endothelial cell density (P = 0.072). In the keratoconus group, increased level of stromal haze, alterations such as the elongation of keratocyte nuclei and clustering of cells at the anterior stroma, and dark bands in the posterior stroma were observed with increased severity of the disease. The mean anterior and posterior stromal keratocyte densities and cell areas among the different stages of keratoconus were significantly different (P < 0.001 and P = 0.044, respectively). However, the changes observed in the endothelium were not significantly different (P > 0.05) among the three stages of keratoconus. Confocal microscopy observation showed significant changes in corneal cell morphology in keratoconic cornea from normal healthy cornea. Analysis also showed significant changes in different severities of keratoconus. Understanding the corneal cell morphology changes in keratoconus may help in the long-term monitoring and management of keratoconus.

In vivo corneal confocal microscopic analysis in patients with keratoconus.

To quantify corneal ultrastructure using laser scanning in vivo confocal microscopy (IVCM) in patients with keratoconus and control subjects. Unscarred corneas of 78 keratoconic subjects without a history of contact lens use and 36 age-matched control subjects were evaluated with slit-lamp examination (SLE), corneal topography and laser scanning IVCM. One eye was randomly chosen for analysis. Anterior and posterior stromal keratocyte, endothelial cell and basal epithelial cell densities and sub-basal nerve structure were evaluated. IVCM qualitatively demonstrated enlarged basal epithelial cells, structural changes in sub-basal and stromal nerve fibers, abnormal stromal keratocytes and keratocyte nuclei, and pleomorphism and enlargement of endothelial cells. Compared with control subjects, significant reductions in basal epithelial cell density (5817±306 cells/mm(2) vs 4802±508 cells/mm(2), P<0.001), anterior stromal keratocyte density (800±111 cells/mm(2) vs 555±115 cells/mm(2), P<0.001), posterior stromal keratocyte density (333±34 cells/mm(2) vs 270±47 cells/mm(2), P<0.001), endothelial cell density (2875±223 cells/mm(2) vs 2686±265 cells/mm(2), P<0.001), sub-basal nerve fiber density (31.2±8.4 nerves/mm(2) vs 18.1±9.2 nerves/mm(2), P<0.001), sub-basal nerve fiber length (21.4±3.4 mm/mm(2) vs 16.1±5.1 mm/mm(2), P<0.001), and sub-basal nerve branch density (median 50.0 (first quartile 31.2 - third quartile 68.7) nerve branches/mm(2) vs median 25.0 (first quartile 6.2 - third quartile 45.3) nerve branches/mm(2), P<0.001) were observed in patients with keratoconus. Significant microstructural abnormalities were identified in all corneal layers in the eyes of subjects with keratoconus using IVCM. This non-invasive in vivo technique provides an important means to define and follow progress of microstructural changes in patients with keratoconus.

Confocal Microscopy Analysis of Corneal Changes After Photorefractive Keratectomy Plus Cross-Linking for Keratoconus: 4-Year Follow-up

To analyze corneal confocal microscopy changes after combined photorefractive keratectomy (PRK) plus the cross linking (CXL) procedure. Prospective interventional case series. At the Department of Basic Medical Sciences, Neuroscience, and Sense Organs of the University of Bari, Bari, Italy, 17 eyes of 17 patients with progressive keratoconus underwent confocal microscopy examination before and after 1, 3, 6, 12, 18, and 48 months following PRK plus the CXL procedure. The main outcome measures were mean superficial epithelial cell density; mean basal epithelial cell density; mean anterior, mid and posterior keratocyte density; qualitative analysis of stromal backscatter; sub-basal and stromal nerve density parameters; and mean endothelial cell density. During the 4-year follow-up, the mean superficial epithelial cell density, mean basal epithelial cell density and mean endothelial cell density remained unchanged (P > 0.05). The anterior mid-stromal keratocyte density showed a significant decrease (P < 0.05) as compared with preoperative values, and the posterior stromal keratocyte density showed a significant increase at 1 and 3 months of follow-up. Sub-basal and stromal nerve density parameters were significantly decreased until postoperative month 6 (P < 0.05 at 1, 3, and 6 months) and then tended to increase up to preoperative values by the 18th postoperative month. Corneal changes after the PRK plus CXL procedures seem to be pronounced and long lasting as far as keratocyte density of the anterior and mid stroma is concerned. Sub-basal nerve densities tend to reach preoperative values 6 months after surgery.

Evaluation of Contact Lens–Induced Changes in Keratoconic Corneas Using In Vivo Confocal Microscopy

To quantitatively analyze laser scanning in vivo confocal microscopy (IVCM) images of all corneal layers in contact lens-wearing and noncontact lens-wearing keratoconus patients. The study population included rigid gas permeable (RGP) contact lens-wearing keratoconus patients (group 1; N = 29), keratoconus patients who did not wear contact lenses (group 2; N = 30), and subjects who neither had keratoconus nor wore contact lenses (group 3; N = 30), with groups 2 and 3 matched to group 1 by age and sex. The central cornea was examined with IVCM in all subjects. The mean duration of contact lens wear was 5.50 ± 3.68 years (range, 2-15 years). Eyes with keratoconus showed significantly lower basal epithelial cell and anterior and posterior stromal keratocyte densities, as well as subbasal nerve fiber density, nerve branch density, and nerve fiber length compared with healthy control subjects. Furthermore, compared with group 2, group 1 had significantly lower basal epithelial cell density (4920 ± 476 cells/mm(2) vs. 4503 ± 461 cells/mm(2), P = 0.001) and anterior stromal keratocyte density (561 ± 91 cells/mm(2) vs. 464 ± 55 cells/mm(2), P < 0.001), but there was no significant difference for posterior stromal keratocyte density (P = 0.808), endothelial cell density (P = 0.699), or subbasal nerve fiber density (P = 0.142), nerve branch density (P = 0.614), and nerve fiber length (P = 0.850). Significant corneal microstructural abnormalities were observed in eyes with keratoconus. RGP contact lens wear was associated with a further reduction in the basal epithelial cell and anterior stromal keratocyte densities, but with no effect on posterior stromal keratocyte density, endothelial cell density, or corneal nerve morphology.

Evaluation of Corneal Microstructure in Keratoconus: A Confocal Microscopy Study

To compare the corneal microstructure in patients with manifest keratoconus (KCN), subclinical KCN, and topographically normal relatives of patients with KCN and in healthy controls. Prospective and cross-sectional study. We enrolled 145 subjects in the study. The participants were divided into 4 groups, based on clinical and topographical evaluation: the manifest KCN group (n = 30), the subclinical KCN group (n = 32), the KCN relatives group (n = 53), and the control group (n = 30). Corneal microstructure was assessed by corneal in vivo confocal microscopy in all of the individuals. Mean outcome measures were basal epithelial cell density, endothelial cell density, anterior keratocyte density, posterior keratocyte density, sub-basal nerve density, sub-basal nerve diameter, and stromal nerve diameter. The mean basal epithelial cell density, endothelial cell density, and sub-basal nerve diameter were not significantly different among the 4 groups (P = 0.057, P = 0.592, and P = 0.393, respectively). The mean anterior and posterior stromal keratocyte densities were significantly lower in the manifest group, in the subclinical group, and in the relatives group when compared with the control group (for both parameters; P < 0.001, P < 0.001, and P< 0.001, respectively). The mean stromal nerve diameter in the manifest group, subclinical group, and relatives group was significantly higher than in the control group (P = 0.001, P = 0.049, and P = 0.004, respectively). The anterior and posterior stromal keratocyte densities were statistically lower and stromal nerve diameter was statistically higher in patients with manifest KCN, subclinical KCN, and topographically normal KCN relatives compared with controls. Confocal microscopy may be useful for the determination of early corneal microstructural changes before manifestation of typical or subtle topographic signs.

Assessment of Keratocyte Density in Patients With Keratoconus Not Using Contact Lenses

To assess the keratocyte density (KD) in the cornea of patients with keratoconus not using contact lenses. In this pilot study, the eyes (n = 68) of 35 patients with the diagnosis of keratoconus, who did not use contact lenses and the eyes(n = 70) of 35 healthy controls were prospectively examined using the Heidelberg Retinal Tomography Rostock cornea module (HRT3/RCM). The cases with keratoconus and controls were compared with regard to KD in the anteroposterior stromal layers. Of the cases with keratoconus, 15 (42.9%) were men and 20 (57.1%) were women. The mean age was 21.1 ± 11.1 (range =14-41) years. Of the controls, 26 (73.9%) were men and 9 (26.1%)were women. The mean age was 23.9 ± 12.9 (range = 14-35) years.Of the 68 eyes with keratoconus, 22 (28.2%) had mild keratoconus, 23 (35.9%) had moderate keratoconus, and 23 (35.9%) had severe keratoconus. The mean anterior stromal KD was 651.4 ± 89 cells per square millimeter in cases with keratoconus and 879.4 ± 75 cells per square millimeter in controls (P < 0.05). The mean anterior stromal KD decreased by 25.9% in corneas with keratoconus. The mean posterior stromal KD was found to be 363.6 ± 74 cells per square millimeter in cases with keratoconus and 469.7 ± 56 cells per square millimeter in controls (P< 0.01). The mean posterior stromal KD decreased by 22.6% in corneas with keratoconus. The anterior stromal KD was higher than the posterior stromal KD (P < 0.001). No significant relationships were found between the stromal KD data and central corneal thickness or steepest keratometric. The KD in the anterior and posterior corneal stroma was decreased in patients with keratoconus, but without the use of contact lens, compared with healthy controls. This density difference was independent from the central corneal thickness and the stage of keratoconus.

Cellular effects of mitomycin-C on human corneas after photorefractive keratectomy

To investigate the effects of mitomycin-C (MMC) on epithelial and keratocyte cell kinetics after photorefractive keratectomy (PRK) using an in vitro human cornea model. Department of Academic Ophthalmology, Rayne Institute, St. Thomas' Hospital, London, United Kingdom. Twenty-four human eye-bank corneas were placed in a specially designed acrylic corneal holder and cultured using the air-interface organ culture technique for up to 4 weeks. The corneas were divided into 3 groups. Group 1 consisted of 8 human corneas that had -9.00 diopter (D) myopic PRK without MMC application. Group 2 consisted of 8 corneas that had -9.00 D PRK with MMC (0.2 microg/mL) application for 1 minute on the stromal surface after ablation. Group 3 consisted of 8 corneas that had -9.00 D PRK with 2-minute exposure to MMC (0.2 microg/mL). Temporal events in epithelial and keratocyte cell kinetics were evaluated using digital imaging, confocal microscopy, and light microscopy. Epithelial latency was significantly delayed with MMC application in Groups 2 and 3 (P<.001). Epithelial migration was delayed in Group 3 (2-minute exposure) compared to migration in Group 2 (P<.04), with a consequent delay in epithelial closure (P<.001). Group 3 corneas had poorly differentiated epithelium that was significantly thinner than in Groups 1 and 2 (P<.0001). A significant delay in keratocyte regeneration occurred after MMC application (P<.0005). At 4 weeks, the anterior stromal cell density was significantly lower in Group 3 than Group 2 (P<.001). There were no significant differences in the mid- and posterior stromal keratocyte density between the groups. Results suggest that epithelial healing after MMC is characterized by prolonged latency and decreased migration rate dependent on exposure time. Mitomycin C application did not result in increased loss of keratocytes, but it significantly delayed keratocyte repopulation in the anterior stroma. The use of MMC 0.2 microg/mL for 1 minute resulted in optimum modulation of healing characterized by reduced keratocyte activation with normal epithelial differentiation.

Clinical and In Vivo Confocal Microscopy Findings in Patients Receiving Tamoxifen Citrate

: To describe the deposition rate of tamoxifen in the cornea and observe its impact on the cornea with confocal microscopy. : Forty-four eyes of 22 women receiving tamoxifen at a dosage of 20 mg/day for at least 6 months for the adjuvant treatment of breast cancer and 30 eyes of 15 healthy age-matched women were examined for corneal drug deposition by slitlamp after pupil dilation. Ultrasound pachymetry, specular microscopy, in vivo confocal microscopy, and Schirmer tear test were also performed in all patients. : The mean duration of tamoxifen intake was 21.6 +/- 7.9 months (range, 13-44 months), and the mean cumulative dose was 12.9 +/- 4.7 g (range, 7.8-26.4 g). Drug depositions in the inferior paracentral cornea were identified in 32 (72%) eyes at pupil-dilated slitlamp examination. There were no significant differences between eyes with keratopathy, those without keratopathy, and control eyes in regard to the mean Schirmer test scores, mean central corneal thickness, mean endothelial cell count, mean basal epithelium cell density, mean anterior and posterior stromal keratocyte density, and mean endothelial cell density (P > 0.05). No pathologic alteration of structure was observed with in vivo confocal microscopy at any corneal level in patients receiving tamoxifen. : Low-dose tamoxifen use was associated with corneal depositions in 72% of patients. Slitlamp examination performed with pupil dilation was helpful in detection of subtle tamoxifen-related deposits. Amelioration of in vivo confocal microscopy systems may be helpful in accurate imaging of the paracentral and peripheral cornea.

In Vivo Confocal Microscopy Findings in Keratoconus

: To evaluate corneal structure in eyes with keratoconus by using in vivo confocal microscopy. : In a prospective institutional study, 48 eyes of 24 consecutive patients with keratoconus were examined by in vivo confocal microscopy. Forty-four eyes of 22 healthy subjects served as the control. The main outcome measures were qualitative and quantitative changes encountered at confocal microscopy examination. : In the keratoconus group, in vivo confocal microscopy findings included elongated, exfoliating superficial epithelial cells; brightly reflective material deposition within the basal epithelial cells; prominent, thickened subbasal nerves; structural changes in subbasal nerve fibers; pronounced reflectivity and irregular arrangement of stromal keratocytes; structurally abnormal anterior stromal keratocyte nuclei; folds in the anterior, mid, and posterior stroma; folds in Descemet's membrane; pleomorphism and enlargement of endothelial cells; and endothelial guttata. No such abnormal findings were present in the control group. There were significant differences between the two groups in terms of the mean basal epithelial, anterior and posterior stromal keratocyte densities, the mean basal epithelial cell area, and the mean endothelial cell hexagonality percentages. : Quantitative and qualitative structural changes were observed in all corneal layers in eyes with keratoconus by using slit-scanning confocal microscopy. The changes at all levels were more prominent in eyes with severe keratoconus. This noninvasive in vivo technique may prove to be useful in the diagnosis and follow-up of keratoconus and in the understanding of its pathophysiology.

Quantitative analysis of corneal microstructure in keratoconus utilising in vivo confocal microscopy

To establish and quantify the in vivo confocal microscopic features of moderate to advanced keratoconus. Nineteen keratoconus subjects were catergorised using Orbscan-derived corneal apex power and pachymetry as exhibiting moderate (n=7) and advanced (n=12) keratoconus. Control subjects included 23 noncontact lens wearers (Group A) and 15 contact lens wearers (Group B). All subjects underwent Confoscan slit scanning in vivo confocal microscopy. Compared with Group A (4912+/-434 cells/mm(2)), basal epithelial density was significantly lower in both moderate (4592+/-414 cells/mm(2), P<0.05) and advanced keratoconus (4530+/-596 cells/mm(2), P=0.01). In comparison to Group A (761+/-118 cells/mm(2)), anterior stroma keratocyte density was significantly greater in both moderate keratoconus (883+/-111 cells/mm(2), P=0.001) and advanced keratoconus (952+/-122 cells/mm(2), P<0.001). Compared to Group A (504+/-80 cells/mm(2)) posterior stroma keratocyte density was also significantly greater in advanced keratoconus (599+/-97 cells/mm(2), P<0.001) and posterior stromal keratocyte density appeared to increase with increasing severity of keratoconus (P<0.05). However, comparing control Groups A and B, contact lens wear per se, was associated with significantly reduced (P=0.000) keratocyte density in the anterior stroma (609+/-66 cells/mm(2)) and demonstrated a trend (P=0.056) in the posterior stroma (470+/-63 cells/mm(2)). Keratoconic corneas (429+/-72 microm) were significantly thinner than control Groups A (508+/-77 mm) and B (495+/-80 microm). The presence of keratoconus did not affect the endothelial cell density (P=0.54). In vivo confocal microscopy can provide insight into the microstructural changes that occur in keratoconus.

Confocal microscopic observations of stromal keratocytes during extended contact lens wear

Background: The aim of this study was to monitor changes in keratocyte density during extended contact lens wear and to explore the possible role of hypoxia and oedema in any changes observed. Methods: Twenty‐three neophyte myopic subjects wore a high Dk/t lens (Pure Vision) in one eye and a low Dk/t lens (Acuvue 2) in the other eye on an extended wear basis for six months. Slit‐scanning confocal microscopy and ultrasonic pachometry were performed on both eyes at baseline (before lens wear), after three and six months of lens wear, and one week after cessation of lens wear (the ‘post‐cessation’ visit). Results: No differences were established between die two lenses or between the three study visits for anterior stromal keratocyte density (KD). Posterior stromal KD was similar for the two lenses throughout the study. However, there was an overall drop in posterior KD of 14 per cent in bodl eyes at the six‐month visit, compared to die initial visit. Posterior KD at die six‐mondi visit was no different from diat at die post‐cessation visit. Corneal thickness was similar for die two lenses at die initial and post‐cessation visits, but was diree per cent greater for the eye wearing die Acuvue 2 lens at die six‐month visit. Conclusion: Extended contact lens wear causes a loss of keratocytes; diis loss cannot be attributed to contact lens‐induced hypoxia and/or oedema, or to an artifact of confocal microscopy relating to presence of residual oedema. It is postulated diat lens‐induced keratocyte loss may be related to die physical presence of contact lenses creating some mechanical effect.

Effect of lens wear on corneal stroma: preliminary findings.

The aim of the study was to measure the effects of long-term extended wear of hydrogel lenses. Nine subjects wearing disposable hydrogel lenses and age- and sex-matched non-lens-wearing control subjects were enrolled. Using confocal microscopy, stromal keratocyte cell densities were measured. Anterior stromal keratocyte density was reduced in the lens-wearing group (544+/-206 cells/mm2) compared to the non-lens-wearing group (804+/-145 cells/mm2) (P < 0.01). Posterior stromal keratocyte density was lower in the lens-wearing group (514+/-111 cells/mm2) than in the control group (628+/-101 cells/mm2) (P < 0.05). These preliminary findings indicate that extended wear of hydrogel lenses reduces stromal keratocyte density. The mechanisms for this alteration may include hypoxic, cytokine-mediated or mechanical effects.