Decoding cellular plasticity and niche regulation of limbal stem cells during corneal wound healing.

BACKGROUND: Dysfunction or deficiency of corneal epithelium results in vision impairment or blindness in severe cases. The rapid and effective regeneration of corneal epithelial cells relies on the limbal stem cells (LSCs). However, the molecular and functional responses of LSCs and their niche cells to injury remain elusive. METHODS: Single-cell RNA sequencing was performed on corneal tissues from normal mice and corneal epithelium defect models. Bioinformatics analysis was performed to confirm the distinct characteristics and cell fates of LSCs. Knockdown of Creb5 and OSM treatment experiment were performed to determine their roles of in corneal epithelial wound healing. RESULTS: Our data defined the molecular signatures of LSCs and reconstructed the pseudotime trajectory of corneal epithelial cells. Gene network analyses characterized transcriptional landmarks that potentially regulate LSC dynamics, and identified a transcription factor Creb5, that was expressed in LSCs and significantly upregulated after injury. Loss-of-function experiments revealed that silencing Creb5 delayed the corneal epithelial healing and LSC mobilization. Through cell-cell communication analysis, we identified 609 candidate regeneration-associated ligand-receptor interaction pairs between LSCs and distinct niche cells, and discovered a unique subset of Arg1+ macrophages infiltrated after injury, which were present as the source of Oncostatin M (OSM), an IL-6 family cytokine, that were demonstrated to effectively accelerate the corneal epithelial wound healing. CONCLUSIONS: This research provides a valuable single-cell resource and reference for the discovery of mechanisms and potential clinical interventions aimed at ocular surface reconstruction.

Extensive Contact Lens Wear Modulates Expression of miRNA-320 and miRNA-423-5p in the Human Corneal Epithelium: Possible Biomarkers of Corneal Health and Environmental Impact.

The identification of new biomarkers of ocular diseases is nowadays of outmost importance both for early diagnosis and treatment. Epigenetics is a rapidly growing emerging area of research and its involvement in the pathophysiology of ocular disease and regulatory mechanisms is of undisputable importance for diagnostic purposes. Environmental changes may impact the ocular surface, and the knowledge of induced epigenetic changes might help to elucidate the mechanisms of ocular surface disorders. In this pilot study, we investigated the impact of extensive contact lens (CL) wearing on human corneal epithelium epigenetics. We performed ex vivo analysis of the expression of the miR-320 and miR-423-5p involved in the processes of cellular apoptosis and chronic inflammation. The human corneal epithelium was harvested from healthy patients before the photorefractive keratectomy (PRK). The patients were divided into two age- and sex-matched groups accordingly to CL wearing history with no CL wearers used as a control. The epithelium was stored frozen in dry ice at -80 °C and forwarded for miRNA extraction; afterwards, miRNA levels were detected using real-time PCR. Both miRNAs were highly expressed in CL wearers (p < 0.001), suggesting epigenetic modifications occurring in chronic ocular surface stress. These preliminary results show the relationships between selected miRNA expression and the chronic ocular surface stress associated with extensive CL use. MicroRNAs might be considered as biomarkers for the diagnosis of ocular surface conditions and the impact of environmental factors on ocular surface epigenetic. Furthermore, they might be considered as new therapeutic targets in ocular surface diseases.

Intraoperative variability of corneal epithelium thickness in photorefractive keratectomy.

PURPOSE: To evaluate the intraoperative central corneal epithelial thickness (ET) as measured by optical coherence pachymetry (OCP) in myopic eyes undergoing alcohol-assisted photorefractive keratectomy (PRK). METHODS: A retrospective review of patients who underwent alcohol-assisted PRK was performed. Data were abstracted on age, gender, contact lens (CL) wear, preoperative refractive errors, keratometry, topographic and ultrasonic pachymetry, and intraoperative OCP measurements before and after epithelium removal. The central ET was calculated by subtracting OCP measurement after epithelium removal from the OCP measurement prior to epithelium removal. RESULTS: The study comprised of 162 consecutive eyes from 81 patients. Mean age was 26.73 ± 6.47 years, 50.6% were males. CL was used in 92 eyes (56.8%). The mean sphere and spherical equivalent were -3.60 ± 1.84 D and -3.26 ± 1.85D, respectively. The mean intraoperative ET was 58.22 ± 17.53 µm (range, 15-121µm). Fifty-five percent of the eyes had an ET measurement above or below the range of 40-60µm. ET was significantly higher in the second operated eye compared to the first operated eye (p = 0.006), and an association was found to CL-wear (p = 0.03). There was no significant difference in thickness between genders (p = 0.62), and no correlation to patient age (p = 0.45, rp = 0.06), refractive errors (p > 0.30,rp=-0.07-0.08), nor keratometry(p > 0.80, rp=-0.01- (-0.02)). CONCLUSION: The intraoperative assessment of ET in alcohol-assisted PRK showed a high variability of the central corneal epithelium, with a significant difference between the first and second operated eyes. This difference may have implications when the epithelium is not included in the surgical planning in surface ablation.

Epithelial thickness map-adjusted transepithelial photorefractive keratectomy for treatment of myopic astigmatism: 12-month results.

PURPOSE: To evaluate the refractive results of Transepithelial Photorefractive Keratectomy (t-PRK) with the Technolas Teneo2 Excimer laser platform. METHODS: In this retrospective comparative interventional case series, a total of 199 patients with myopia ranging from - 1 to - 7 diopters were enrolled and separated into three groups based on their target refraction of zero (group 1), - 0.25 (group 2), and - 0.5 diopters (group 3), respectively. The main outcome measure was post-operative cycloplegic refraction. Trans-PRK was performed using the Technolas Teneo2 Excimer laser. To prevent any remaining epithelium during stromal ablation, we adopted the thickest epithelial point in the 7 mm central map as the reference for Phototherapeutic keratectomy (PTK) depth. Patients were examined three and twelve months after the procedure, and the results were analyzed. RESULTS: At the 12-month follow-up, uncorrected distance visual acuity was 20/20 in all patients. However, there was a significant difference in cycloplegic spherical equivalent refraction between the three groups. The 12-month post-operative spherical equivalent refraction was 0.90 ± 0.33 D, 0.79 ± 0.26 D, and 0.60 ± 0.19 D in groups 1, 2, and 3, respectively (P < 0.001; Kruskal-Wallis test). The rates of spherical equivalent refraction of more than 0.75 D were 58.3%, 39.1%, and 9.1% in the 0 D, - 0.25 D, and -0.50 D groups, respectively (P < 0.001; Chi-squared test). CONCLUSIONS: The t-PRK with Technolas Teneo2 Excimer laser and epithelial thickness map adjustment of PTK induce a significant amount of residual hyperopia (> 0.75 D) in a large proportion of eyes with a target refraction of 0 or - 0.25, which is significantly reduced by using a target refraction of - 0.5.

Salzmann's Nodular Degeneration in Refractive Surgery: The Earlier Hit Hypothesis of EBM Injury-Related Fibrosis of the Subepithelial Space and Deeper Corneal Extension.

PURPOSE: To review the atypical development of Salzmann's nodular degeneration (SND) after two cases of laser in situ keratomileusis (LASIK) and one case of photorefractive keratomileusis (PRK), and to highlight the pathophysiology of SND and its treatment. METHODS: Three cases of SND (two following LASIK performed with microkeratomes and one following PRK) were reviewed and Pubmed.gov and internet searches were performed. RESULTS: SND is myofibroblast-generated fibrosis in the subepithelial space between the epithelium and Bowman's layer that develops years or decades after traumatic, surgical, infectious, or inflammatory injuries to the cornea in which the epithelial basement membrane is damaged in one or more locations and does not fully regenerate. It is hypothesized based on these cases, and the previous immunohistochemistry of other investigators, that myofibroblast precursors, such as fibrocytes or corneal fibroblasts, that enter the subepithelial space are driven to develop into myofibroblasts, which slowly proliferate and extend the fibrosis, by transforming growth factor-beta from epithelium and tears that passes through the defective epithelial basement membrane. These myofibroblasts and the disordered collagens, and other extracellular matrix components they produce, make up the subepithelial opacity characteristic of SND. Nodules are larger accumulations of myofibroblasts and disordered extracellular matrix. If the injury is associated with damage to the underlying Bowman's layer and stroma, as in LASIK flap generation, then the myofibroblasts and fibrosis can extend into Bowman's layer and the underlying anterior stroma. CONCLUSIONS: SND fibrosis often extends into Bowman's layer and the anterior stroma if there are associated Bowman's defects, such as incisions or lacerations. In the latter cases, SND frequently cannot be removed by simple scrape and peel, as typically performed for most common SND cases, but can be trimmed to remove the offending tissue. This condition is more accurately termed Salzmann's subepithelial fibrosis. [J Refract Surg. 2024;40(5):e279-e290.].

Central toxic keratopathy leading to epithelial ingrowth following femtosecond LASIK.

We report a case of a woman in her 30s who underwent femtosecond LASIK (laser-assisted in situ keratomileusis) in both eyes to correct her simple myopic astigmatism. After the surgery, both eyes developed diffuse lamellar keratitis, and intensive topical steroids were initiated to control the same. Subsequently, central toxic keratopathy (CTK) developed bilaterally. Three weeks after the surgery, the right eye showed signs of progressive epithelial ingrowth involving the pupillary area. Surgical intervention in the form of flap relift followed by debridement of the epithelial cells and an alcohol interface wash were performed to treat the same. This is the first report of an epithelial ingrowth following CTK after femtosecond LASIK.

DNMT1 driven by mouse amniotic fluid mesenchymal stem cell exosomes improved corneal cryoinjury via inducing microRNA-33 promoter DNA hypermethylation modification in corneal epithelium cells.

Severe corneal cryoinjury can cause permanent corneal swelling and bullous keratopathy, one of the main reason for loss of sight. Mouse amniotic fluid mesenchymal stem cells (mAF-MSCs) can repair corneal damage caused by freezing; however, whether the exosomes derived from mAF-MSCs have the same repair effect is unknown. In this study, the mAF-MSC-exosomes were transplanted into the eyeballs of corneal cryoinjured mice. Histopathological examination showed that the mAF-MSC-exosomes improved the corneal structure and status of corneal epithelial cells in corneal cryoinjured mice. RRBS-sequencing showed that compared with the control group, four genes (Rpl13-ps6, miR-33, Hymai, and Plagl1), underwent DNA hypermethylation modification after mAF-MSC-exosomes treatment. The result of FISH indicated that miR-33-3p hybridization signals were enhanced in corneal epithelial cells from mice treated with mAF-MSC-exosomes. Semi-quantitative PCR and western blotting indicated that mAF-MSC-exosomes contained high levels of DNMT1 mRNA and protein. Additionally, luciferase report assays indicated that miR-33-3p overexpression in NIH-3T3 mouse embryonic fibroblast cells inhibited the activity of luciferase carrying a sequence from the 3' untranslated region of Bcl6. Moreover, BCL6 mRNA and protein levels in corneal tissues from mice treated with mAF-MSC-exosomes were higher than those in the control group. Therefore, our results suggested that mAF-MSC-exosomes could repair corneal cryoinjury by releasing DNMT1, which induced hypermethylation of the miR-33 promoter in corneal epithelial cells. Consequent downregulated miR-33 transcription upregulated Bcl6 expression, ultimately achieving the repair of corneal cryoinjury in mice.

Comparative effectiveness of nitro dihydrocapsaicin, new synthetic derivative capsaicinoid, and capsaicin in alleviating oxidative stress and inflammation on lipopolysaccharide-stimulated corneal epithelial cells.

Loss of tear homeostasis, characterized by hyperosmolarity of the ocular surface, induces cell damage through inflammation and oxidation. Transient receptor potential vanilloid 1 (TRPV1), a sensor for osmotic changes, plays a crucial role as a calcium ion channel in the pathogenesis of hypertonic-related eye diseases. Capsaicin (CAP), a potent phytochemical, alleviates inflammation during oxidative stress events by activating TRPV1. However, the pharmacological use of CAP for eye treatment is limited by its pungency. Nitro dihydrocapsaicin (NDHC) was synthesized with aromatic ring modification of CAP structure to overcome the pungent effect. We compared the molecular features of NDHC and CAP, along with their biological activities in human corneal epithelial (HCE) cells, focusing on antioxidant and anti-inflammatory activities. The results demonstrated that NDHC maintained cell viability, cell shape, and exhibited lower cytotoxicity compared to CAP-treated cells. Moreover, NDHC prevented oxidative stress and inflammation in HCE cells following lipopolysaccharide (LPS) administration. These findings underscore the beneficial effect of NDHC in alleviating ocular surface inflammation, suggesting that NDHC may serve as an alternative anti-inflammatory agent targeting TRPV1 for improving hyperosmotic stress-induced ocular surface damage.

PAX6/CXCL14 regulatory axis promotes the repair of corneal injury by enhancing corneal epithelial cell proliferation.

BACKGROUND: Corneal injuries, often leading to severe vision loss or blindness, have traditionally been treated with the belief that limbal stem cells (LSCs) are essential for repair and homeostasis, while central corneal epithelial cells (CCECs) were thought incapable of such repair. However, our research reveals that CCECs can fully heal and maintain the homeostasis of injured corneas in rats, even without LSCs. We discovered that CXCL14, under PAX6's influence, significantly boosts the stemness, proliferation, and migration of CCECs, facilitating corneal wound healing and homeostasis. This finding introduces CXCL14 as a promising new drug target for corneal injury treatment. METHODS: To investigate the PAX6/CXCL14 regulatory axis's role in CCECs wound healing, we cultured human corneal epithelial cell lines with either increased or decreased expression of PAX6 and CXCL14 using adenovirus transfection in vitro. Techniques such as coimmunoprecipitation, chromatin immunoprecipitation, immunofluorescence staining, western blot, real-time PCR, cell colony formation, and cell cycle analysis were employed to validate the axis's function. In vivo, a rat corneal epithelial injury model was developed to further confirm the PAX6/CXCL14 axis's mechanism in repairing corneal damage and maintaining corneal homeostasis, as well as to assess the potential of CXCL14 protein as a therapeutic agent for corneal injuries. RESULTS: Our study reveals that CCECs naturally express high levels of CXCL14, which is significantly upregulated by PAX6 following corneal damage. We identified SDC1 as CXCL14's receptor, whose engagement activates the NF-κB pathway to stimulate corneal repair by enhancing the stemness, proliferative, and migratory capacities of CCECs. Moreover, our research underscores CXCL14's therapeutic promise for corneal injuries, showing that recombinant CXCL14 effectively accelerates corneal healing in rat models. CONCLUSION: CCECs play a critical and independent role in the repair of corneal injuries and the maintenance of corneal homeostasis, distinct from that of LSCs. The PAX6/CXCL14 regulatory axis is pivotal in this process. Additionally, our research demonstrates that the important function of CXCL14 in corneal repair endows it with the potential to be developed into a novel therapeutic agent for treating corneal injuries.

Uneven Corneal Epithelial Redistribution After Femtosecond Laser-Assisted Lenticule Intrastromal Keratoplasty in Correcting Moderate-to-High Hyperopia.

PURPOSE: To evaluate the characteristic of corrective epithelial thickness after femtosecond laser-assisted lenticule intrastromal keratoplasty (LIKE) to correct moderate-to-high hyperopia. METHODS: The prospective case series study of the LIKE procedure was performed to correct moderate-to-high hyperopia. The epithelial thickness map was generated by anterior segment optical coherence tomography (AS-OCT) in the corneal central 9-mm zone. Keratometry and corneal higher order aberrations were analyzed by Pentacam (Oculus Optikgeräte GmbH) preoperatively and postoperatively. RESULTS: In the 26 eyes of 13 participants who underwent the LIKE procedure for moderate-to-high hyperopia, the attempted spherical equivalence (SEQ) was +6.50 ± 1.09 diopters (D). Compared to the preoperative epithelial thickness maps, the postoperative epithelial thickness had become significantly thinner in the central 5-mm zone; the difference was 6 to 7 µm. The paracentral epithelium performed nonuniform remodeling; the thinnest epithelial thickness was located in the inferotemporal section, which has the greatest difference from the superonasal; the difference between these two was approximately 3 µm. Through correlation analysis, it was found that the sections with thinner epithelium were significantly related to corneal curvature and corneal vertical coma. CONCLUSIONS: The LIKE procedure can be used to correct moderate-to-high hyperopia. This study further indicated the epithelial remodeling characteristic after the LIKE procedure: the central and paracentral corneal epithelial thickness becomes thinner, and the epithelial thickness distributes non-uniformly, which may be the important factor of the postoperative curvature asymmetric distribution and induction of corneal vertical coma. [J Refract Surg. 2024;40(5):e321-e327.].

The effect of sodium hyaluronate on dry eye and corneal epithelial thickness following cataract surgery.

PURPOSE: To evaluate the effects of sodium hyaluronate drops on dry eye parameters and corneal epithelial thickness following cataract surgery. METHODS: The study included 84 patients who underwent uncomplicated phacoemulsification. In Group A, 0.15% sodium hyaluronate drops were added to the postoperative antibiotic/anti-inflammatory treatment. In Group B, only antibiotic/anti-inflammatory treatment was applied. Preoperatively and at 1 week and 1 month postoperatively, all the patients were evaluated in respect of tear break-up time (TBUT), the Schirmer test under anesthesia, the corneal fluorescein staining (CFS) score, mean central corneal thickness (CCT) and mean central corneal epithelial thickness (CCET), and the two groups were compared. RESULTS: A statistically significant difference was determined between the two groups at postoperative 1 month in respect of TBUT, Schirmer test, CFS score, and CCET (p < 0.01). In Group A, a statistically significant increase was determined in the TBUT and Schirmer values at 1 month postoperatively (p < 0.01, p = 0.01, respectively) and in Group B, these values were decreased compared to preoperatively (p < 0.01). The CCET was determined to be significantly thinner in Group B 1 month postoperatively (p < 0.01). A significant increase in CCT was observed in both groups at postoperative 1 week (p < 0.01) and preoperative values were reached at 1 month postoperatively. CONCLUSION: In the patient group using sodium hyaluronate, significant differences were determined in all dry eye parameters and CCET. The use of hyaluronate sodium drops after cataract surgery was seen to improve dry eye parameters and contribute to a healthy ocular surface by ensuring continuity of the corneal epithelium.

Impact of Obesity and Age on Mouse Corneal Innervation at the Epithelial-Stromal Interface.

Purpose: The corneal epithelium is the most highly innervated structure in the body. Previously, we reported a novel event whereby stromal axons fuse with basal epithelial cells, limiting nerve penetration into the epithelium. Although corneal-epithelial nerves undergo changes in sensitivity and distribution throughout life and in response to an obesogenic diet, it is unknown if neuronal-epithelial cell fusion is altered. Here, we sought to determine if neuronal-epithelial cell fusion frequency correlates with obesogenic diet consumption and age. Methods: Corneas were collected from C57BL/6 mice and evaluated for neuronal-epithelial cell fusion frequency using serial block-face scanning electron microscopy. To assess the correlation between diet-induced obesity and fusion frequency, 6-week-old mice were fed either a normal diet or an obesogenic diet for 10 weeks. To assess changes in fusion frequency between young and adult mice under normal dietary conditions, 9- and 24-week-old mice were used. Results: Mice fed a 10-week obesogenic diet showed 87% of central-cornea stromal nerves engaged in fusion compared with only 54% in age-matched controls (16 weeks old). In 9-week-old normal-diet animals, 48% of central-cornea stromal nerves contained fusing axons and increased to 81% at 24 weeks of age. Corneal sensitivity loss correlated with increased body weight and adiposity regardless of age and diet. Conclusions: Neuronal-epithelial cell fusion positively correlates with age and obesogenic diet consumption, and corneal nerve sensitivity loss correlates with increased body weight and adiposity, regardless of age and diet. As such, neuronal-epithelial cell fusion may play a role in corneal nerve density and sensitivity regulation.

Topical insulin for refractory persistent corneal epithelial defects.

The aim was clinical evaluation of the efficacy of topical insulin eye drops in patients with refractory persistent epithelial defects (PEDs). This prospective non-randomized investigation was conducted to examine the efficacy of insulin eye drops in treating patients with PEDs that did not respond to conventional therapy. A total of twenty-three patients were included in the study, and they were administered insulin eye drops formulated as 1 U/mL, four times a day. The rate of epithelial defect resolution and time to complete corneal re-epithelialization were considered primary outcome measures. The relative prognostic impact of initial wound size and other parameters, including age, sex, smoking, diabetes, and hypertension were also analyzed. The results showed that during follow-up (maximum 50 days), a total of 16 patients (69.6%) achieved improvement. Insulin eye drops significantly reduced the corneal wounding area in 75% of patients with small epithelial defects (5.5 mm2 or less) during 20 days. Only 61% of patients with moderate epithelial defects (5.51-16 mm2) showed a significant recovery in 20-30 days. Also, 71% of patients with a defect size greater than 16 mm2, demonstrated a significant improvement in the rate of corneal epithelial wound healing in about 50 days. In conclusion topical insulin reduces the PED area and accelerates the ocular surface epithelium wound healing.

Commercial human 3D corneal epithelial equivalents for modeling epithelial infection in herpes keratitis.

Herpes stromal keratitis is the leading cause of infectious blindness in the western world. Infection by HSV1 is most common, but VZV and hCMV also infect the cornea. Multiple models of HSV1 corneal infection exist, but none for VZV and hCMV because of their host specificity. Here, we used commercially available 3D human corneal epithelial equivalents (HCEE) to study infection by these herpesviruses. HCEE was infected by HSV-1 and hCMV without requiring scarification and resulted in spreading infections. Spread of HSV-1 infection was rapid, while that of hCMV was slow. In contrast, infections with VZV required damage to the HCEE and did not spread. Acyclovir dramatically reduced replication of HSV-1 in this model. We conclude that highly quality-controlled, readily available HCEE is a useful model to study human-restricted herpesvirus infection of the human corneal epithelium and for screening of antiviral drugs for treating HSK in an 3D model system.

In vivo assessment of human corneal epithelial cells in orthokeratology lens wearers: A pilot study.

SIGNIFICANCE: Central corneal epithelial thinning associated with midperipheral epithelial thickening has been reported as the main factor contributing to the effectiveness of orthokeratology (ortho-k) in myopia control. Yet, the cellular mechanism governing the regional change in refractive power remains elusive. PURPOSE: This study aimed to evaluate the correlation between the regional change in corneal epithelial thickness and cell density in ortho-k wearers. METHODS: A new human prototype of a polarization-dependent optical coherence microscope was developed to enable noncontact and noninvasive in vivo imaging of corneal epithelial cells in ortho-k wearers with and without their ortho-k lens. The epithelial thickness and cell density were evaluated at the central and midperipheral corneal locations in four ortho-k wearers and four spectacle wearers serving as controls. RESULTS: Polarization-dependent optical coherence microscope achieved in vivo volumetric imaging of all epithelial cell types in ortho-k wearers with and without their lens over a field of view of 0.5 × 0.5 mm 2 with an isotropic resolution of ~2.2 mm. The central epithelial thinning and midperipheral epithelial thickening were consistent across all ortho-k wearers. However, the inconsistency in their regional epithelial cell density highlighted a great variability in individual response to ortho-k treatment. There was no strong correlation between epithelial thickness and cell density, especially at the midperipheral cornea, in ortho-k participants. CONCLUSIONS: This study constitutes our first step toward uncovering the cellular mechanism underlying the effectiveness of ortho-k in myopia control. Future studies will focus on the longitudinal evaluation of epithelial cells before and during ortho-k treatment to identify factors governing individual response to ortho-k treatment and ultimately inform the dynamics of epithelial cells taking place during the ortho-k treatment.

Mucoadhesive phenylboronic acid-grafted carboxymethyl cellulose hydrogels containing glutathione for treatment of corneal epithelial cells exposed to benzalkonium chloride.

Benzalkonium chloride (BAK) is the most commonly-used preservative in topical ophthalmic medications that may cause ocular surface inflammation associated with oxidative stress and dry eye syndrome. Glutathione (GSH) is an antioxidant in human tears and able to decrease the proinflammatory cytokine release from cells and reactive oxygen species (ROS) formation. Carboxymethyl cellulose (CMC), a hydrophilic polymer, is one of most commonly used artificial tears and can promote the corneal epithelial cell adhesion, migration and re-epithelialization. However, most of commercial artificial tears provide only temporary relief of irritation symptoms and show the short-term treatment effects. In the study, 3-aminophenylboronic acid was grafted to CMC for increase of mucoadhesive properties that might increase the precorneal retention time and maintain the effective therapeutic concentration on the ocular surface. CMC was modified with different degree of substitution (DS) and characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Phenylboronic acid (PBA)-grafted CMC hydrogels have interconnected porous structure and shear thinning behavior. Modification of CMC with high DS (H-PBA-CMC) shows the strong bioadhesive force. The optimal concentration of GSH to treat corneal epithelial cells (CECs) was evaluated by cell viability assay. H-PBA-CMC hydrogels could sustained release GSH and decrease the ROS level. H-PBA-CMC hydrogels containing GSH shows the therapeutic effects in BAK-damaged CECs via improvement of inflammation, apoptosis and cell viability. After topical administration of developed hydrogels, there was no ocular irritation in rabbits. These results suggested that PBA-grafted CMC hydrogels containing GSH might have potential applications for treatment of dry eye disease.

High phosphate and calcium induce osteoblastic phenotype switching and calcification of corneal epithelial cells in a Runx2-dependent and synergistic manner; a possible mechanism of chronic kidney disease-associated corneal calcification.

Patients with advanced chronic kidney disease (CKD) have elevated circulating calcium × phosphate product levels and exhibit soft tissue calcification. Besides the cardiovascular system, calcification is commonly observed in the cornea in CKD patients on hemodialysis. Cardiovascular calcification is a cell-mediated, highly regulated process, and we hypothesized that a similar regulatory mechanism is implicated in corneal calcification with the involvement of corneal epithelial cells (CECs). We established a mouse model of CKD-associated corneal calcification by inducing CKD in DBA/2J mice with an adenine and high phosphate diet. CKD was associated with aorta and corneal calcification as detected by OsteoSense staining and corneal Ca measurement (1.67-fold elevation, p < 0.001). In vitro, excess phosphate and Ca induced human CEC calcification in a dose-dependent and synergistic manner, without any influence on cell viability. High phosphate and Ca-containing osteogenic medium (OM; 2.5 mmol/L excess phosphate and 0.6 mmol/L excess Ca over control) increased the protein expression of Runx2 and induced its nuclear translocation. OM increased the expression of the bone-specific Ca-binding protein osteocalcin (130-fold increase, p < 0.001). Silencing of Runx2 attenuated OM-induced CEC calcification. Immunohistology revealed upregulation of Runx2 and overlapping between the Runx2 and the Alizarin red positive areas of calcification in the cornea of CKD mice. This work sheds light on the mechanism of CKD-induced corneal calcification and provides tools to test calcification inhibitors for the prevention of this detrimental process.

Clinical features and comprehensive treatment of persistent corneal epithelial dysfunction after cataract surgery.

OBJECTIVE: Evaluation of clinical efficacy and safety of tobramycin/dexamethasone eye ointment in treating persistent corneal epithelial dysfunction (PED) after cataract surgery. METHODS: 26 cases diagnosed as PED after cataract surgery accept the tobramycin/dexamethasone ophthalmic ointment and intense pulse light treatment in the Xiamen University of Xiamen eye center between September 2016 and April 2022 were retrospectively analyzed, mainly including clinical manifestations, characteristics of morphological changes imaged by in vivo confocal microscopy, meibomian glands infrared photography, lipid layer thickness (LLT), management and therapeutic effects. RESULTS: There were 26 eyes, include 8(35%) males and 15(65%) females with an average age of 69.6 ± 5.2 years(50 to 78 years). The mean hospitalization time was (18.4 ± 7.5) days after cataract surgery. Twenty patients had meibomian gland dysfunction. Infrared photography revealed varying loss in the meibomian glands, with a mean score of 3.8 ± 1.2 for gland loss. The mean LLT was 61.6 ± 8.4 nm. After treatment, 20 patients were cured, and 3 received amniotic membrane transplantation. After treatment, the uncorrected visual acuity (UCVA) and best-corrected vision activity (BCVA) improved (P < 0.001), and there was no significant difference in intraocular pressure (IOP) before and after treatment (P > 0.05). CONCLUSIONS: The early manifestation of PED after surgery is punctate staining of the corneal epithelium. Tobramycin and dexamethasone eye ointment bandages have a good repair effect. The meibomian gland massage combined with intense pulse light treatment can effectively shorten the course of the disease.

Redistribution of Epithelium and Stroma and Their Relationship With Corneal Curvature After 1-Month Cessation of Overnight Orthokeratology.

OBJECTIVES: To investigate the changes in the thickness of epithelium and stroma and their relationship with corneal curvature following the cessation of overnight orthokeratology for a period of 1 month. METHODS: This prospective study consecutively included 20 juveniles (20 right eyes) who had undergone overnight orthokeratology for a minimum of one year and were willing to discontinue the treatment. The study measured and compared epithelial and corneal curvature using optical coherence tomography and Medmont topographer at the first day of cessation and 1 month after cessation. In addition, changes in uncorrected visual acuity and refractive error before and after the cessation of the treatment were analyzed. RESULTS: The study found a significant increase in the thickness of the epithelium in the central 2-mm area after the cessation of the treatment (t = -4.807, P <0.001). Moreover, the stroma in the paracentral area (2-5 mm) and peripheral area (5-6 mm) showed a general thinning trend ( P =0.016, P =0.016). Regarding the correlation analysis, the change in central epithelial thickness (ΔCET) was significantly correlated with the change in paracentral corneal curvature (ΔPCCC) (r=0.610, P =0.007) and the change in peripheral corneal curvature (ΔPCC) (r=0.597, P =0.009). Similarly, the change in central stromal thickness (ΔCST) was significantly correlated with the change in central corneal curvature (ΔCCC) (r=0.500, P =0.035), ΔPCCC (r=0.700, P =0.001), and ΔPCC (r=0.635, P =0.005). CONCLUSIONS: The study found that the corneal remodeling induced by orthokeratology was reversible after the cessation of the treatment. Specifically, changes in the epithelium were found to be more prominent in the central area, while changes in the stroma were more pronounced in the paracentral and peripheral areas. In addition, the study established a significant correlation between central corneal remodeling and changes in curvature.