Molecular detection of lacrimal apparatus and ocular surface - related ABC transporter genes.

The ocular system is in constant interaction with the environment and with numerous pathogens. The ATP-binding cassette (ABC) transporters represent one of the largest groups among the transmembrane proteins. Their relevance has been demonstrated for their defense function against biotic and abiotic stress factors, for metabolic processes in tumors and for their importance in the development of resistance to drugs. The aim of this study was to analyze which ABC transporters are expressed at the ocular surface and in the human lacrimal apparatus. Using RT-PCR, all ABC transporters known to date in humans were examined in tissue samples from human cornea, conjunctiva, meibomian glands and lacrimal glands. The RT-PCR analyses revealed the presence of all ABC transporters in the samples examined, although the results for some of the 48 transporters known in human and analyzed were different in the various tissues. The present results provide information on the expression of ABC transporters at the mRNA level on the ocular surface and in the lacrimal system. Their detection forms the basis for follow-up studies at the protein level, which will provide more information about their physiological significance at the ocular surface and in the lacrimal system and which may explain pathological effects such as drug resistance.

The Potential Reversible Transition between Stem Cells and Transient-Amplifying Cells: The Limbal Epithelial Stem Cell Perspective.

Stem cells (SCs) undergo asymmetric division, producing transit-amplifying cells (TACs) with increased proliferative potential that move into tissues and ultimately differentiate into a specialized cell type. Thus, TACs represent an intermediary state between stem cells and differentiated cells. In the cornea, a population of stem cells resides in the limbal region, named the limbal epithelial stem cells (LESCs). As LESCs proliferate, they generate TACs that move centripetally into the cornea and differentiate into corneal epithelial cells. Upon limbal injury, research suggests a population of progenitor-like cells that exists within the cornea can move centrifugally into the limbus, where they dedifferentiate into LESCs. Herein, we summarize recent advances made in understanding the mechanism that governs the differentiation of LESCs into TACs, and thereafter, into corneal epithelial cells. We also outline the evidence in support of the existence of progenitor-like cells in the cornea and whether TACs could represent a population of cells with progenitor-like capabilities within the cornea. Furthermore, to gain further insights into the dynamics of TACs in the cornea, we outline the most recent findings in other organ systems that support the hypothesis that TACs can dedifferentiate into SCs.

Erratum: Single cell analysis of short-term dry eye induced changes in cornea immune cell populations.

[This corrects the article DOI: 10.3389/fmed.2024.1362336.].

Comparison of Corneal Biomechanical Efficacy Between Rose Bengal-Green Light and Riboflavin-UVA Crosslinking.

PURPOSE: To investigate corneal biomechanical changes after corneal cross-linking (CXL) treatments with rose bengal-green light (RB-CXL) and riboflavin-UVA (RF-CXL). METHODS: A total of 60 freshly enucleated lamb eyes were obtained for this experimental study. Fifteen eyes were treated with RB-CXL using 0.1% RB solution (Group 1), 15 eyes were treated with RB-CXL using 0.2% RB solution (Group 2), 15 eyes were treated with RF-CXL using 0.1% RF solution (Group 3), and 15 eyes were used as controls (Group 4). The same treatment protocol (10-minute irradiation using a total of 5.4 J/cm2 energy) was applied to all treatment groups. To evaluate corneal biomechanical changes, the stress-strain test was used for both the treated and control corneas. The elastic modulus was calculated using the tension strain curves obtained during the test. RESULTS: The average elastic modulus values were calculated to be 18.9, 23.5, 22.3, and 14.1 MPa in Groups 1, 2, 3, and 4, respectively. Statistically significant differences were found between the groups (p < 0.001 for Group 1 vs. 2; p < 0.001 for Group 1 vs. 3; p < 0.001 for Group 1 vs. 4; p = 0.002 for Group 2 vs. 3; p < 0.001 for Group 2 vs. 4; and p < 0.001 for Group 3 vs. 4). CONCLUSIONS: In this study, the efficacy of RB-CXL treatment applied using different concentrations of RB solutions at a total energy of 5.4 J/cm2 was investigated, and 0.2% RB solution was found to have at least as much and even more effective than the RF-CXL (0.1% RF) on the corneal elasticity module. These results are encouraging for the treatment of ectatic corneas particularly below 400 µm. It is considered that the findings obtained from this study will guide future experimental and clinical studies.

Ocular surface complications in children undergoing general anaesthesia: A prospective observational study.

OBJECTIVE: Ophthalmic complications frequently occur after procedures requiring general anaesthesia, but their incidence is widely variable and not well reported in the paediatric population. The aim was to identify the incidence and possible risk factors of postoperative ocular surface complications in a tertiary care centre. METHODS AND ANALYSIS: This is a prospective study for paediatric patients undergoing general anaesthesia. An ophthalmologist performed the ocular examination after surgery. Parameters assessed were tear breakup time, punctate epithelial erosions and corneal abrasions. Multivariate logistic regression model was used to assess risk factors. RESULTS: A total of 108 paediatric patients were recruited, 36.1% showed abnormal corneal finding: 32 (29.6%) had decreased tear breakup time, three (2.7%) had punctate epithelial erosions, three (2.7%) had both punctate epithelial erosions and decreased tear breakup time and one (0.9%) was found to have a unilateral corneal abrasion postoperatively. A higher rate of corneal complications was noted with younger age, prolonged surgery and surgery in the head and neck region. CONCLUSION: The rate of postoperative corneal abnormalities in children undergoing general anaesthesia was 36.1%, associated with younger age, prolonged surgery and surgery in the head and neck region.

Cost-Effective Surgical Management of Pterygium: A Blood-Based Adhesion Technique Substituting Fibrin Glue.

Pterygium is a degenerative eye condition marked by the abnormal growth of conjunctival tissue over the cornea, primarily affecting individuals near the equator. When it reaches the cornea's center, patients may experience obstructed and blurry vision, necessitating pterygium surgery. The standard surgical approach involves excision with a blade, using a conjunctival autograft to address the defect, and securing it with fibrin glue. Recurrence rates exhibit variability, with approximately half occurring within the initial three months. In this case, we present a more cost-effective surgical approach, avoiding the use of a blade to minimize intraoperative complications. Additionally, autologous blood is employed instead of fibrin glue. We evaluate immediate and post-operative complications, as well as the incidence of recurrence rates at the three-month mark.

The Spiral of Tillaux: dead on accurate; a cadaveric study.

INTRODUCTION: The Spiral of Tillaux describes the historically accepted insertion distances of the medial rectus, inferior rectus, lateral rectus, and superior rectus from the limbus: 5.5 mm, 6.5 mm, 6.9 mm, and 7.7 mm, respectively. The corneal diameters are historically accepted to be 11.7 mm horizontally and 10.6 mm vertically in adults. We investigated the variability of the insertion distances of the extraocular rectus muscles from the limbus as well as the corneal diameters using eyes from human cadavers and compared our measurements to these historically accepted measurements. METHODS: A sample of 60 eyes were included. For each eye, a 360 peritomy was conducted and the conjunctiva bluntly dissected to view the sclera. Muscle hooks were utilized to isolate the extraocular rectus muscles. Calipers were used to measure the insertion distances of the rectus muscles as well as the corneal diameters. RESULTS: The mean rectus muscle insertions distances from the limbus were medial 5.28 mm, inferior 5.72 mm, lateral 6.40 mm, and superior 6.78 mm. These insertion distances were shorter than the historical benchmarks (p < .01). However, observed maximum distances of the rectus muscles were all greater than the historically accepted benchmarks, with the medial, inferior, lateral, and superior rectus muscles being 6.4 mm, 7.3 mm, 7.4 mm, and 7.8 m from the limbus, respectively. The mean width and height of the cornea were 11.7 mm and 10.7 mm, respectively, and similar to the expected ranges. CONCLUSION: This study concludes that variability does exist from the historically accepted Spiral of Tillaux measurements. In addition, significant variation exists between male and female rectus muscle insertions. However, we did confirm that the rectus muscles followed the same spiral pattern described by the Spiral of Tillaux and concluded that the corneal diameters are consistent with previously accepted values.

Intravital imaging of the human cornea reveals the differential effects of season on innate and adaptive immune cell morphodynamics.

PURPOSE: While the external environment has been shown to shape the systemic human immune landscape, defining the in vivo immune status of peripheral tissues has remained a technical challenge. We recently developed functional in vivo confocal microscopy (Fun-IVCM) for dynamic, longitudinal imaging of corneal immune cells in living humans. This study investigated the effect of seasonal-driven environmental factors on the density, morphology and dynamic behavior of human corneal immune cell subsets. DESIGN: Longitudinal, observational clinical study. PARTICIPANTS: Sixteen healthy participants (18-40 years) attended two visits in distinct seasons in Melbourne, Australia (Visit 1: Spring/Summer: November-December 2021; Visit 2: Autumn/Winter: April-June 2022). METHODS: Environmental data were collected over each period. Participants underwent ocular surface examinations and corneal Fun-IVCM (Heidelberg HRT-3, Rostock Corneal Module). Volume scans (80µm) were acquired at 5.5±1.5 minute intervals, for up to five timepoints. Time-lapse videos were created to analyze corneal immune cells, comprising epithelial T cells and dendritic cells (DCs), and stromal macrophages. Tear cytokines were analyzed using multiplex bead-based immunoassay. MAIN OUTCOME MEASURES: Difference in the density, morphological and dynamic parameters of corneal immune cell subsets over the study periods. RESULTS: Visit 1 was characterized by higher temperature, lower humidity, and higher air particulate and pollen levels than Visit 2. Clinical ocular surface parameters, and the density of immune cell subsets were similar across visits. At Visit 1 (Spring/Summer), corneal epithelial DCs were larger and more elongated, with a lower dendrite probing speed (0.38±0.21 vs 0.68±0.33µm/min, p<0.001) relative to Visit 2; stromal macrophages were more circular and had less dynamic activity (Visit 1: 7.2±1.9 vs Visit 2: 10.3±3.7 'dancing index', p<0.001). T cell morphology and dynamics were unchanged across periods. Basal tear levels of IL-2 and CXCL10 were lower during Spring/Summer. CONCLUSION: This novel study shows that the in vivo morphodynamics of innate corneal immune cells (DCs, macrophages) are modified by environmental factors, but such effects are not evident for adaptive immune cells (T cells). The cornea is a potential non-invasive, in vivo 'window' to season-dependent changes to the human immune system, with capacity to yield new insight into environmental influences on immune regulation.

Elevated Neutrophils and reduced NK cells are associated with altered tear molecular signatures and clinical sequelae of chronic ocular Stevens-Johnson Syndrome.

PURPOSE: Stevens-Johnson syndrome (SJS) is characterised as an immuno-inflammatory condition with potentially blinding ocular sequelae. Therefore, we have investigated the ocular surface immune cell profile and correlated it with secreted tear molecular factors and clinical ocular sequelae in SJS patients. METHODS: 21 patients (42 eyes) with chronic ocular SJS and 16 healthy controls (20 eyes) were included in the study. Severity, types of keratopathies and ocular surface(OS) manifestations were determined. OS wash samples from study subjects were used to determine the status of 13 immune cell subsets using flow cytometry. Levels of 42 secreted immuno-inflammatory factors were measured by flow cytometry-based multiplex ELISA in tear samples. RESULTS: Neutrophils (Total, activated), neutrophils/NK cells ratio, neutrophils/T cells ratio were significantly (p<0.05) elevated in SJS, while, proportions of T cells and NKT cells were significantly lower in SJS patients. Positive association between neutrophils and chronic ocular surface complication score (COCS) was observed, whereas, a negative association was noted between NK cells and COCS. Tear fluid levels of IL-6, IL-8, IL-18, IFNα/ß/γ, TNFα, LIF, IL-8, HGF, sTNFR-I, NGAL, Granzyme, Perforins, MMP9/TIMP1 ratio were significantly higher in SJS. Loss of Limbal niche correlated significantly with immune profile and clinical sequelae. Increased neutrophils, decreased NK cells and specific set of altered secreted immuno-inflammatory mediators including bFGF, and IL-8 were observed in SJS patients with different types of keratopathies compared to those without keratopathy. CONCLUSION: Distinct ocular surface immune profile variations were observed to correlate with clinical stages of chronic ocular SJS. Our findings uncover novel mechanisms and potential for targeted therapy in chronic ocular SJS patients.

Automated Measurement and Three-Dimensional Fitting of Corneal Ulcerations and Erosions via AI-Based Image Analysis.

PURPOSE: Artificial intelligence (AI)-tools hold great potential to compensate for missing resources in health-care systems but often fail to be implemented in clinical routine. Intriguingly, no-code and low-code technologies allow clinicians to develop Artificial intelligence (AI)-tools without requiring in-depth programming knowledge. Clinician-driven projects allow to adequately identify and address real clinical needs and, therefore, hold superior potential for clinical implementation. In this light, this study aimed for the clinician-driven development of a tool capable of measuring corneal lesions relative to total corneal surface area and eliminating inaccuracies in two-dimensional measurements by three-dimensional fitting of the corneal surface. METHODS: Standard slit-lamp photographs using a blue-light filter after fluorescein instillation taken during clinical routine were used to train a fully convolutional network to automatically detect the corneal white-to-white distance, the total fluorescent area and the total erosive area. Based on these values, the algorithm calculates the affected area relative to total corneal surface area and fits the area on a three-dimensional representation of the corneal surface. RESULTS: The developed algorithm reached dice scores >0.9 for an automated measurement of the relative lesion size. Furthermore, only 25% of conventional manual measurements were within a ± 10% range of the ground truth. CONCLUSIONS: The developed algorithm is capable of reliably providing exact values for corneal lesion sizes. Additionally, three-dimensional modeling of the corneal surface is essential for an accurate measurement of lesion sizes. Besides telemedicine applications, this approach harbors great potential for clinical trials where exact quantitative and observer-independent measurements are essential.

[A randomized study of subconjonctival bevacizumab (Avastin®) injection for corneal neovascularization]. / Étude randomisée de l'injection sous-conjonctivale de bévacizumab (Avastin®) dans la néo-vascularisation cornéenne.

PURPOSE: The goal of this phase III, comparative, multicentric, randomized, double-blinded clinical trial was to investigate the superiority of subconjunctival bevacizumab injections versus placebo in the treatment of corneal neovascularization. PATIENTS AND METHODS: We included 38 eyes (38 patients) with corneal neovascularization. Twenty patients received bevacizumab and 18 placebos. Patients received 3 monthly injections of either 5mg (0.2mL) bevacizumab or placebo. The main criteria of success was reduction of the surface area of corneal neovascularization after 3months (M3) versus baseline, as measured using semi-automatic analysis of color photographs. RESULTS: The percentage of neovascularized corneal surface decreased by -8.6%±32.8 with bevacizumab, versus -2.6%±20.8 with placebo (p=0.5284). Four patients were determined to be responders (reduction of more than 30%), 3 in the bevacizumab group and 1 in the placebo group, all with neovascularization of less than 1year duration. When restricting the analysis to neovascularization of less than 1 year duration, the difference approached the threshold for significance (-31.8%±42.4 in the bevacizumab group and -0.9%±23.1 in the placebo group) (p=0.0637), as well as the number of responders (3/6 in the bevacizumab group versus 1/10 in the placebo group) (p=0.1181). No serious adverse event was reported. CONCLUSION: This study shows the efficacy of subconjunctival bevacizumab injection in the reduction of neovascularized corneal surface area versus placebo, but only when the neovascularization has been present less than 1year. Nevertheless, the study did not attain the statistical power to pass the threshold of significance.

Nanohydroxyapatite Coating Attenuates Fibrotic and Immune Responses to Promote Keratoprosthesis Biointegration in Advanced Ocular Surface Disorders.

Keratoprosthesis (KPro) implantation is frequently the only recourse for patients with severe corneal disease. However, problems arise due to inadequate biointegration of the KPro, particularly the PMMA optical cylinder, such as tissue detachment, tissue melting, or eye-threatening infection in the interface. Here, using the AuroKPro as a model prosthesis, a surface functionalization approach─coating the optical cylinder with nanohydroxyapatite (nHAp)─was trialed in rabbit eyes with and without a proceeding chemical injury. In chemically injured eyes, which simulated total limbal epithelial stem cell deficiency, clear benefits were conferred by the coating. The total modified Hackett-McDonald score and area of tissue apposition differences 12 weeks after implantation were 5.0 and 22.5%, respectively. Mechanical push-in tests revealed that 31.8% greater work was required to detach the tissues. These differences were less marked in uninjured eyes, which showed total score and tissue apposition differences of 2.5 and 11.5%, respectively, and a work difference of 23.5%. The improved biointegration could be contributed by the attenuated expression of fibronectin (p = 0.036), collagen 3A1 (p = 0.033), and α-smooth muscle actin (p = 0.045)─proteins typically upregulated during nonadherent fibrous capsule envelopment of bioinert material─adjacent to the optical cylinders. The coating also appeared to induce a less immunogenic milieu in the ocular surface tissue, evidenced by the markedly lower expression of tear proteins associated with immune and stimulus responses. Collectively, the level of these tear proteins in eyes with coated prostheses was 1.1 ± 13.0% of naïve eyes: substantially lower than with noncoated KPros (246.5 ± 79.3% of naïve, p = 0.038). Together, our results indicated that nHAp coating may reduce the risk of prosthesis failure in severely injured eyes, which are representative of the cohort of KPro patients.

Increased tolerance to commonly used antibiotics in a Pseudomonas aeruginosa ex vivo porcine keratitis model.

Introduction. Bacterial keratitis, particularly caused by Pseudomonas aeruginosa, is challenging to treat because of multi-drug tolerance, often associated with the formation of biofilms. Antibiotics in development are typically evaluated against planktonic bacteria in a culture medium, which may not accurately represent the complexity of infections in vivo.Hypothesis/Gap Statement. Developing a reliable, economic ex vivo keratitis model that replicates some complexity of tissue infections could facilitate a deeper understanding of antibiotic efficacy, thus aiding in the optimization of treatment strategies for bacterial keratitis.Methodology. Here we investigated the efficacy of three commonly used antibiotics (gentamicin, ciprofloxacin and meropenem) against Pseudomonas aeruginosa cytotoxic strain PA14 and invasive strain PA01 using an ex vivo porcine keratitis model.Results. Both strains of P. aeruginosa were susceptible to the MIC of the three tested antibiotics. However, significantly higher concentrations were necessary to inhibit bacterial growth in the minimum biofilm eradication concentration (MBEC) assay, with both strains tolerating concentrations greater than 512 mg l-1 of meropenem. When MIC and higher concentrations than MBEC (1024 mg l-1) of antibiotics were applied, ciprofloxacin exhibited the highest potency against both P. aeruginosa strains, followed by meropenem, while gentamicin showed the least potency. Despite this, none of the antibiotic concentrations used effectively cleared the infection, even after 18 h of continuous exposure.Conclusions. Further exploration of antibiotic concentrations and aligning dosing with clinical studies to validate the model is needed. Nonetheless, our ex vivo porcine keratitis model could be a valuable tool for assessing antibiotic efficacy.

Evaluating keratometry and corneal astigmatism data from biometers and anterior segment tomographers and mapping to reconstructed corneal astigmatism.

BACKGROUND: To compare results from different corneal astigmatism measurement instruments; to reconstruct corneal astigmatism from the postimplantation spectacle refraction and toric intraocular lens (IOL) power; and to derive models for mapping measured corneal astigmatism to reconstructed corneal astigmatism. METHODS: Retrospective single centre study involving 150 eyes treated with a toric IOL (Alcon SN6AT, DFT or TFNT). Measurements included IOLMaster 700 keratometry (IOLMK) and total keratometry (IOLMTK), Pentacam keratometry (PK) and total corneal refractive power in 3 and 4 mm zones (PTCRP3 and PTCRP4), and Aladdin keratometry (AK). Regression-based models mapping the measured C0 and C45 components (Alpin's method) to reconstructed corneal astigmatism were derived. RESULTS: Mean C0 components were 0.50/0.59/0.51 dioptres (D) for IOLMK/PK/AK; 0.2/0.26/0.31 D for IOLMTK/PTCRP3/PTCRP4; and 0.26 D for reconstructed corneal astigmatism. All corresponding C45 components ranged around 0. The prediction models had main diagonal elements lower than 1 with some crosstalk between C0 and C45 (nonzero off-diagonal elements). Root-mean-squared residuals were 0.44/0.45/0.48/0.51/0.50/0.47 D for IOLMK/IOLMTK/PK/PTCRP3/PTCRP4/AK. CONCLUSIONS: Results from the different modalities are not consistent. On average IOLMTK/PTCRP3/PTCRP4 match reconstructed corneal astigmatism, whereas IOLMK/PK/AK show systematic C0 offsets of around 0.25 D. IOLMTK/PTCRP3/PTCRP4. Prediction models can reduce but not fully eliminate residual astigmatism after toric IOL implantation.

The Impact of Vaping on the Ocular Surface: A Systematic Review of the Literature.

Background: The use of electronic cigarettes has become increasingly popular in recent years. However, the impact that electronic cigarettes have on the ocular surface is not well known. Therefore, the aim of this review is to explore the current literature on the acute and chronic sequelae of electronic cigarettes on the ocular surface. Methods: A systematic review of the literature was undertaken by keyword searching on the Embase, Medline, and Web of Science databases. Articles identified through the search underwent title/abstract screening, full-text screening, and data extraction. Results: A total of 18 studies were included in this review. Non-intended ocular surface exposures and intended exposures on the ocular surface were found to be associated with the use of electronic cigarettes. Conclusions: The impact of vaping on the ocular surface is not benign. There are significant risks that vaping can pose to the ocular surface. Hence, it is necessary to develop appropriate risk communication tools given the increasing popularity of this activity. Additionally, future long-term studies are needed to better understand the long-term impacts of vaping on the ocular surface given the lack of current data.

Evaluation of the results of contact lens assisted corneal cross-linking treatment in keratoconus patients with thin corneas.

PURPOSE: We aimed to compare the efficacy and safety of accelerated contact lens-assisted cross-linking (CA-CXL) with Lotrafilcon B and Comfilcon A lenses in keratoconus (KC) patients with thin corneas. STUDY DESIGN: Retrospective, single-center study. MATERIALS AND METHODS: We retrospectively included 51 eyes of 39 KC patients with corneal thickness <400µm after epithelial scraping (Epi-off), who underwent accelerated CA-CXL treatment with Lotrafilcon B (n=20) and Comfilcon A (n=31). Uncorrected and corrected distance visual acuity (UDVA and CDVA), manifest refraction values, corneal topographic data and endothelial cell density were recorded at preoperative and postoperative 1st, 3rd and 6th month controls. RESULTS: CDVA in the Comfilcon A group was higher than CDVA before surgery at 6 months postoperatively (p<0.001). When the two lenses were compared, CDVA was found to be significantly higher in the Lotrafilcon B group in the preoperative, postoperative 1st month and 3rd month values, but there was no significant difference between the postoperative 6th month values (p=0.028, p=0.018, p=0.044, p=0.181, respectively). The maximum keratometry (Kmax) value at the 6th month after surgery in the Comfilcon A group was significantly lower than in the Lotrafilcon B group (p=0,009). There was no significant difference between the endothelial cell density values between the groups (p=0.623, p=0.609, p=0.794, p=0.458, respectively). There was no significant difference between the progression, regression, and stability rates of the two groups (p=0.714). CONCLUSIONS: Accelerated CA-CXL with Lotrafilcon B and Comfilcon A silicone hydrogel lenses is a safe and effective method to stop progression in patients with thin corneas.

Single cell analysis of short-term dry eye induced changes in cornea immune cell populations.

Background: Dry eye causes corneal inflammation, epitheliopathy and sensorineural changes. This study evaluates the hypothesis that dry eye alters the percentages and transcriptional profiles of immune cell populations in the cornea. Methods: Desiccating stress (DS) induced dry eye was created by pharmacologic suppression of tear secretion and exposure to drafty low humidity environment. Expression profiling of corneal immune cells was performed by single-cell RNA sequencing (scRNA-seq). Cell differentiation trajectories and cell fate were modeled through RNA velocity analysis. Confocal microscopy was used to immunodetect corneal immune cells. Irritation response to topical neurostimulants was assessed. Results: Twelve corneal immune cell populations based on their transcriptional profiles were identified at baseline and consist of monocytes, resident (rMP) and MMP12/13 high macrophages, dendritic cells (cDC2), neutrophils, mast cells, pre T/B cells, and innate (γDT, ILC2, NK) and conventional T and B lymphocytes. T cells and resident macrophages (rMP) were the largest populations in the normal cornea comprising 18.6 and 18.2 percent, respectively. rMP increased to 55.2% of cells after 5 days of DS. Significant changes in expression of 1,365 genes (adj p < 0.0001) were noted in rMP with increases in cytokines and chemokines (Tnf, Cxcl1, Ccl12, Il1rn), inflammatory markers (Vcam, Adam17, Junb), the TAM receptor (Mertk), and decreases in complement and MHCII genes. A differentiation trajectory from monocytes to terminal state rMP was found. Phagocytosis, C-type lectin receptor signaling, NF-kappa B signaling and Toll-like receptor signaling were among the pathways with enhanced activity in these cells. The percentage of MRC1+ rMPs increased in the cornea and they were observed in the basal epithelium adjacent to epithelial nerve plexus. Concentration of the chemokine CXCL1 increased in the cornea and it heightened irritation/pain responses to topically applied hypertonic saline. Conclusion: These findings indicate that DS recruits monocytes that differentiate to macrophages with increased expression of inflammation associated genes. The proximity of these macrophages to cornea nerves and their expression of neurosensitizers suggests they contribute to the corneal sensorineural changes in dry eye.

Corneal endothelial cell density and associated factors among adults at a regional referral hospital in Uganda: a cross-sectional study.

BACKGROUND: To assess the prevalence of low corneal endothelial cell density and correlates of corneal endothelial cell density among adults attending Mbarara University and Referral Hospital Eye Centre in Uganda. METHODS: In this hospital-based cross-sectional study, participants 18 years and older, were enrolled. We obtained informed consent, and basic demographic data. We also conducted visual acuity, a detailed slit lamp examination, intra-ocular pressure, corneal diameter, tear-film break-up time, keratometry, A-scan, and pachymetry on all participants. A confocal microscope Heidelberg HRT3 was used to examine the central cornea and to obtain the mean cell density (cells/mm2). To calculate the proportion of low endothelial cell density, descriptive statistics were used, whereas correlates of endothelial cell density were assessed, using linear regression analyses. RESULTS: We evaluated a total of 798 eyes of 404 participants aged between 18 and 90 years (males = 187, females = 217). The average endothelial cell density was 2763.6 cells/mm2, and there was a decrease in endothelial cell density with increasing age, irrespective of gender. There was no significant difference in endothelial cell density between males and females. Increasing age (adjusted coefficient - 10.1, p < 0.001), history of smoking (adjusted coefficient - 439.6, p = 0.004), history of ocular surgery (adjusted coefficient - 168.0, p = 0.023), having dry eye (adjusted coefficient - 136.0, p = 0.051), and having arcus senilis (adjusted coefficient - 132.0, p = 0.08), were correlated with lower endothelial cell density. However, increasing corneal diameter (adjusted coefficient 134.0, p = 0.006), increasing central corneal thickness (adjusted coefficient 1.2, p = 0.058), and increasing axial length (adjusted coefficient 65.8, p = 0.026), were correlated with higher endothelial cell density. We found five eyes (0.63%) from different participants with a low endothelial cell density (< 1000cells/mm2). CONCLUSION: Our study established baseline normal ranges of ECD in a predominantly black African population, and found that low ECD is rare in our population. The elderly, smokers, and those with past ocular surgery are the most vulnerable. The low prevalence could be due to a lack of reference values for the black African population.

Replace or Regenerate? Diverse Approaches to Biomaterials for Treating Corneal Lesions.

The inner structures of the eye are protected by the cornea, which is a transparent membrane exposed to the external environment and subjected to the risk of lesions and diseases, sometimes resulting in impaired vision and blindness. Several eye pathologies can be treated with a keratoplasty, a surgical procedure aimed at replacing the cornea with tissues from human donors. Even though the success rate is high (up to 90% for the first graft in low-risk patients at 5-year follow-up), this approach is limited by the insufficient number of donors and several clinically relevant drawbacks. Alternatively, keratoprosthesis can be applied in an attempt to restore minimal functions of the cornea: For this reason, it is used only for high-risk patients. Recently, many biomaterials of both natural and synthetic origin have been developed as corneal substitutes to restore and replace diseased or injured corneas in low-risk patients. After illustrating the traditional clinical approaches, the present paper aims to review the most innovative solutions that have been recently proposed to regenerate the cornea, avoiding the use of donor tissues. Finally, innovative approaches to biological tissue 3D printing and xenotransplantation will be mentioned.