Nicotinamide promotes the differentiation of functional corneal endothelial cells from human embryonic stem cells.

Corneal transplantation represents the primary therapeutic approach for managing corneal endothelial dysfunction, but corneal donors remain scarce. Anterior chamber cell injection emerges as a highly promising alternative strategy for corneal transplantation, with pluripotent stem cells (PSC) demonstrating considerable potential as an optimal cell source. Nevertheless, only a few studies have explored the differentiation of functional corneal endothelial-like cells originating from PSC. In this investigation, a chemical-defined protocol was successfully developed for the differentiation of functional corneal endothelial-like cells derived from human embryonic stem cells (hESC). The application of nicotinamide (NAM) exhibited a remarkable capability in suppressing the fibrotic phenotype, leading to the generation of more homogeneous and well-distinctive differentiated cells. Furthermore, NAM effectively suppressed the expression of genes implicated in endothelial cell migration and extracellular matrix synthesis. Notably, NAM also facilitated the upregulation of surface marker genes specific to functional corneal endothelial cells (CEC), including CD26 (-) CD44 (-∼+-) CD105 (-) CD133 (-) CD166 (+) CD200 (-). Moreover, in vitro functional assays were performed, revealing intact barrier properties and Na+/K+-ATP pump functionality in the differentiated cells treated with NAM. Consequently, our findings provide robust evidence supporting the capacity of NAM to enhance the differentiation of functional CEC originating from hESC, offering potential seed cells for therapeutic interventions of corneal endothelial dysfunction.

Correlation of retrobulbar perfusion deficits with glaucomatous visual field defects.

PURPOSE: This study is to evaluate the correlation between retrobulbar perfusion deficits and glaucomatous visual field defects. METHODS: Eighty-four patients with glaucoma and 17 normal subjects serving as controls were selected. Color Doppler imaging (CDI) was used to measure the changes in blood flow parameters in the retrobulbar ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary arteries (SPCAs). Visual field testing was performed using a Humphrey perimeter, categorizing the visual field deficits into four stages according to the Advanced Glaucoma Intervention Study (AGIS) scoring method. Subsequently, the correlation of retrobulbar hemodynamic parameter alterations among glaucomatous patients with varying visual field defects was examined. RESULTS: The higher the visual field stage, the lower the peak systolic velocity (PSV) of the OA, CRA, and SPCAs in glaucomatous patients. The CRA had the highest sensitivity to changes in its PSV. The PSV of the temporal SPCA (TSPCA-PSV) was lower in advanced glaucoma than in early-stage glaucoma. The PSVs of the OA, CRA, and TSPCA, as well as the resistance index of the CRA (CRA-RI), were positively correlated with the visual field index and the mean deviation. Except for that of OA, the PSV of the retrobulbar vessels was negatively correlated with the pattern standard deviation (PSD). The OA-PSV and end-diastolic velocity (EDV) of the CRA and TSPCA were lower in patients with superior visual field defects than in those with inferior visual field defects. CONCLUSIONS: Greater severity of visual field defects corresponded to poorer retrobulbar blood flow in glaucomatous patients. Patients suffered significant perfusion impairments in the CRA at the early stage, accompanied by SPCA perfusion disorder at the advanced stage. The presence of a bow-shaped defect in the superior or inferior region of the visual field in moderate-stage glaucoma was closely correlated with retrobulbar vascular EDV. TRIAL REGISTRATION: ChiCTR2200059048 (2022-04-23).

Characteristics of bacterial community in eyelashes of patients with Demodex blepharitis.

BACKGROUND: Demodex blepharitis (DB) is a common disease of the ocular surface. The characteristics of the bacterial community in eyelash roots after Demodex infestation are still unknown. Knowledge of the characteristics of the bacterial community of eyelash follicles in patients with DB can provide valuable insights for guiding the diagnosis and treatment of DB. METHODS: Twenty-five patients with DB (DB group) and 21 non-DB volunteers (control group) were enrolled in the study. Eyelashes from the upper eyelid of the right eye were sampled, and 16S ribosomal DNA (rDNA) sequencing was performed to determine the V3-V4 regions of the microbial 16S rDNA gene within 1 month of infestation. The sequencing data of the two groups were analyzed and compared. The effect of the bacterium Burkholderia on the survival of Demodex mites was evaluated using Demodex obtained from 12 patients with DB other that the patients in the DB group. RESULTS: A total of 31 phyla and 862 genera were identified in the DB and control groups. The five most abundant phyla in the two groups were Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes and Cyanobacteria. The abundance of Actinomycetes was significantly higher in the DB group than in the control group. At the genus level, the five most abundant genera in the two groups were Pseudomonas, Burkholderia-Caballeronia-Paraburkholderia, Rolstonia and Acinetobacter; Clostridium sensu stricto 1 was abundant in the control group and Corynebacterium_1 was abundant in the DB group. Compared with the control group, the abundance of Burkholderia-Caballeronia-Paraburkholderia was 2.36-fold lower in the DB group. Linear discriminant analysis Effect Size (LEfSe) analysis revealed Burkholderia-Caballeronia-Paraburkholderia, SC_I_84_unclassified, Nonmyxobacteria and Succinvibrio to be the major biomarkers in the control group and Catenibacterium and Lachnospiraceae NK4A136 group to be the major biomarkers in the DB group. To explore the performance of these optimal marker models, receiver operational characteristic curve analysis was performed, and the average area under the curve value of Burkholderia-Caballeronia-Paraburkholderia was 0.7448. Burkholderia cepacia isolated from normal human eyelashes was fermented, and the Demodex mites isolated from patient eyelashes were cultured together with its fermented supernatant. The results showed that the fermentation supernatant could significantly reduce the survival time of the Demodex mites, suggesting the potential therapeutic value of this bacterium against Demodex. CONCLUSIONS: The composition of the bacterial community in the eyelashes of DB patients differed from that in eyelashes of healthy volunteers, revealing a decrease in bacterial diversity in infested eyelashes. This decrease may be related to the occurrence and development of DB. The supernatant of Burkholderia cepacia culture medium was found to inhibit the growth of Demodex in eyelash hair follicles, providing a new insight with potential applications for the clinical treatment of Demodex infestation.

Comparison of the clinical efficacy of orthokeratology and 0.01% atropine for retardation of myopia progression in myopic children.

OBJECTIVE: To compare the clinical efficacy of orthokeratology (ortho-k) and 0.01% atropine for retardation of myopia progression in myopic children. METHODS: This was a retrospective cohort study. A total of 282 patients, aged 8-17 years, were enrolled, including 100 children treated with ortho-k, 84 with 0.01% atropine, and 98 with single-vision spectacles. During the follow-up of 1 year, ortho-k wearers were examined at 1 day, 1 week, 1 month, 3 months after treatment, and thereafter every 3 months, while the others were examined every 3 months by measurements of uncorrected vision, intraocular pressure, refractive power, slit-lamp microscopy, corneal topography, and the lens fitting when necessary. The axial length was measured every 6 months. RESULTS: Patients with ortho-k had stable uncorrected vision after 1 month of lens wear, all reaching 0 logMAR. The annual axial elongation was 0.23 ± 0.19 mm, 0.22 ± 0.20 mm, and 0.39 ± 0.27 mm in the ortho-k, atropine, and spectacle groups, respectively, with significant difference (F = 23.251, P = 0.000). The axial length was delayed to increase by 41.03% and 43.59% within a year in patients with ortho-k and atropine, respectively, as compared to patients with spectacles (F = 0.006, P = 0.936). The elongation was ≤ 0.3 mm in 69.0% and 66.7% of patients in the two groups, respectively, versus 38.8% in the spectacle group (χ2 = 17.251, P = 0.000). During the follow-up, the rate of corneal staining was 11.0% and 2.0% in the ortho-k and spectacle groups, respectively (χ2 = 8.076, P = 0.003). The use of atropine did not increase corneal staining, but the incidence of related photophobia was 4.8%. No other serious complications were observed. CONCLUSION: Ortho-k lenses and 0.01% atropine can achieve similar efficacy of myopia retardation, which was significantly better than that obtained with single-vision spectacles, in myopic children. The risk of corneal staining after ortho-k wear may be slightly higher than that with spectacles, but could be well controlled.

Alterations of conjunctival microbiota associated with orthokeratology lens wearing in myopic children.

BACKGROUND: Orthokeratology (OK) lens wear increases the risk of bacterial infection, but little is known about the microbiota of the conjunctival sac in myopic children wearing OK lenses. This study aimed to investigate the changes of conjunctival microbiota in children after treatment with OK lenses using 16 S rDNA sequencing. METHODS: Twenty-eight myopic children who had been continuously wearing OK lenses for 12 to 13 months were enrolled in this prospective study. Twenty-two gender- and age-matched myopic children who had not worn OK lenses or discontinued OK lens wear at least 1 year ago were recruited as controls. Conjunctival swabs from each participant were collected for exploration of the microbiota profiles, targeting the V3-V4 regions of the 16 S rRNA gene by MiSeq sequencing. The differences in the microbial community structure and diversity were also compared between groups. RESULTS: The bacterial alpha diversity indices in the OK lens group were not different from those in the non-wearer group (P > 0.05, Wilcoxon test), while beta diversity examined using principle coordinate analysis of unweighted UniFrac divided the two groups into different clusters. Proteobacteria, Bacteroidetes, and Firmicutes were the abundant phyla in the conjunctival sac microbiota in both groups (P < 0.05, Mann-Whitney U test). Among children in the OK lens group, the Linear discriminant analysis Effect Size identified the compositional changes in OK lens-associated bacteria. Key functional genera such as Blautia, Parasutterella, and Muribaculum were enriched, whereas Brevundimonas, Acinetobacter, Proteus, and Agathobacter decreased significantly (P < 0.05, Mann-Whitney U test). Phylogenetic investigation of communities by reconstruction of unobserved states also showed altered bacterial metabolic pathways in OK lens-associated microbiota. Moreover, using receiver operating characteristic curves, Brevundimonas, Acinetobacter, Proteus, and Agathobacter alone (the area under the curve was all > 0.7500) or in combination (the area under the curve was 0.9058) were revealed to discriminate OK lens wearers from controls. CONCLUSIONS: The relative abundance of the microbial community in the conjunctival sac of myopic children can alter after OK lens wear. Brevundimonas, Acinetobacter, Proteus, and Agathobacter may be candidate biomarkers to distinguish between OK lens wearers and non-wearers.

Development of Thermoplastic Polyurethane Films for the Replacement of Corneal Endothelial Function of Transparency Maintenance.

Endothelial keratoplasty is the main surgical procedure for treating corneal endothelial dysfunction (CED), which is limited by the global shortage of donor corneas. Herein, we developed and evaluated the modified thermoplastic polyurethane (M-TPU) films with gelatin-glycidyl methacrylate to replace the corneal endothelial function and maintain corneal transparency. The films displayed comparable light transmission characteristics with normal corneas and clinically favorable mechanical properties for surgical manipulation. After surface modification, the hydrophilicity and biocompatibility of M-TPU films were significantly improved. In the rabbit CED model, the M-TPU implants exhibited firm adhesion to the exposed stromal surface. The rabbit corneal transparency and thickness could be restored completely within 1 week of M-TPU film implantation. There was no significant inflammatory reaction and immune rejection during the follow-up of 1 month. Proteomic analysis suggested that the complement inhibition, the increase of mineral absorption, and the decrease of P53 apoptosis signaling pathway and lysine degradation might be beneficial in maintaining the corneal transparency. Overall, our study demonstrated the potential of M-TPU films as artificial implants for the replacement of corneal endothelial function to restore corneal thickness and transparency.

New dawn for keratoconus treatment: potential strategies for corneal stromal regeneration.

Keratoconus is a progressive, ectatic and blinding disorder of the cornea, characterized by thinning of corneal stroma. As a highly prevalent among adolescents, keratoconus has been a leading indication for corneal transplantation worldwide. However, the severe shortage of donor corneas is a global issue, and the traditional corneal transplantation surgeries may superinduce multiple complications, necessitating efforts to develop more effective strategies for keratoconus treatment. In this review, we summarized several strategies to promote corneal stromal regeneration or improve corneal stromal thickness, including cell-based therapies, biosynthetic alternatives for inducing corneal regeneration, minimally invasive intrastromal implantation and bioengineered tissues for implantation. These strategies provided more accessible but safer alternatives from various perspectives for keratoconus treatment, paving the way for arresting the keratoconus progression in its earlier stage. For the treatments of corneal ectatic diseases beyond keratoconus, these approaches will provide important references and widen the therapy options in a donor tissue-independent manner.

Exosomal miR-181d-5p Derived from Rapamycin-Conditioned MDSC Alleviated Allograft Rejection by Targeting KLF6.

Immune rejection and side effects of long-term administration of immunosuppressants are the two major obstacles to allograft acceptance and tolerance. The immunosuppressive extracellular vesicles (EVs)-based approach has been proven to be effective in treating autoimmune/inflammatory disorders. Herein, the anti-rejection advantage of exosomes (Rapa-Exo) from rapamycin-conditioned myeloid-derived suppressor cells (MDSCs) over exosomes (Exo-Nor) from the untreated MDSCs is shown. The exosomal small RNA sequencing and loss-of-function assays reveal that the anti-rejection effect of Rapa-Exo functionally relies on miR-181d-5p. Through target prediction and double-luciferase reporter assay, Kruppel-like factor (KLF) 6 is identified as a direct target of miR-181d-5p. Finally, KLF6 knockdown markedly resolves inflammation and prolongs the survival of corneal allografts. Taken together, these findings support that Rapa-Exo executes an anti-rejection effect, highlighting the immunosuppressive EVs-based treatment as a promising approach in organ transplantation.

Microbiological Characteristics and Risk Factors Involved in Progression from Fungal Keratitis with Hypopyon to Keratitis-Related Endophthalmitis.

PURPOSE: To investigate the differences in microbiological characteristics, risk factors, drug resistance, and visual outcomes in three infections: fungal keratitis with hypopyon (FKH), keratitis-related fungal endophthalmitis (FKE), and fungal endophthalmitis without keratitis (FE). METHODS: An analytical cross-sectional study. RESULTS: In total, 14.57% of eyes with FKH progressed to endophthalmitis. Hypopyon, pre-existence of lens problems, topical steroid use and sever keratitis were significantly associated with the development of FKE. The risk factors of the FKH and FE group were mainly plant trauma and open globe trauma, respectively. Keratitis-related endophthalmitis (FKE) showed a significantly higher resistance than the other two groups. The FKH group had the best final visual acuity, while the FKE group had the worst. CONCLUSION: Hypopyon height, pre-existing lens problems, topical steroid use and sever keratitis are risk factors for progression to endophthalmitis in eyes with fungal keratitis, and its progression is not affected by a single fungus. The antifungal drugs resistance in patients with endophthalmitis related to keratitis was significantly higher than that associated with other reasons. Timely diagnosis and risk factor assessment are essential for ensuring early treatment of FKE.

Immune tolerance induced in the anterior chamber ameliorates corneal transplant rejection.

The relevance of regulatory T cells (Tregs) in induction of tolerance against corneal allografts has been well established. However, whether Tregs can be induced in the anterior chamber and suppress local alloimmune response after corneal transplantation is largely unknown. In the current study we report that not only can alloantigen specific Tregs be generated in the anterior chamber during corneal transplantation, they also play important roles in suppressing allograft rejection. Allograft rejected mice exhibit reduced Treg induction in the anterior chamber and the ability of aqueous humor and corneal endothelial cells from allograft rejected mice to induce Tregs is compromised. Further analysis revealed that the expression of immune-tolerance-related molecules is significantly decreased. Finally, we demonstrate that increasing Treg cells specifically in the anterior chamber can effectively suppress allograft rejection and exhibits better efficacy in promoting corneal allograft survival than systemic administration of Treg cells. Our current study may provide new ideas for the prevention and treatment of corneal transplant rejection.

Ex vivo cultivated retinal pigment epithelial cell transplantation for the treatment of rabbit corneal endothelial dysfunction.

OBJECTIVE: Stem cell therapy is a promising strategy for the treatment of corneal endothelial dysfunction, and the need to find functional alternative seed cells of corneal endothelial cells (CECs) is urgent. Here, we determined the feasibility of using the retinal pigment epithelium (RPE) as an equivalent substitute for the treatment of corneal endothelial dysfunction. METHODS: RPE cells and CECs in situ were obtained from healthy New Zealand male rabbits, and the similarities and differences between them were analyzed by electron microscopy, immunofluorescent staining, and quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). Rabbit primary RPE cells and CECs were isolated and cultivated ex vivo, and Na+/K+-ATPase activity and cellular permeability were detected at passage 2. The injection of cultivated rabbit primary RPE cells, CECs and human embryonic stem cell (hESC)-derived RPE cells was performed on rabbits with corneal endothelial dysfunction. Then, the therapeutic effects were evaluated by corneal transparency, central corneal thickness, enzyme linked immunosorbent assay (ELISA), qRT-PCR and immunofluorescent staining. RESULTS: The rabbit RPE cells were similar in form to CECs in situ and ex vivo, showing a larger regular hexagonal shape and a lower cell density, with numerous tightly formed cell junctions and hemidesmosomes. Moreover, RPE cells presented a stronger barrier and ionic pumping capacity than CECs. When intracamerally injected into the rabbits, the transplanted primary RPE cells could dissolve corneal edema and decrease corneal thickness, with effects similar to those of CECs. In addition, the transplantation of hESC-derived RPE cells exhibited a similar therapeutic effect and restored corneal transparency and thickness within seven days. qRT-PCR results showed that the expressions of CEC markers, like CD200 and S100A4, increased, and the RPE markers OTX2, BEST1 and MITF significantly decreased in the transplanted RPE cells. Furthermore, we have demonstrated that rabbits transplanted with hESC-derived RPE cells maintained normal corneal thickness and exhibited slight pigmentation in the central cornea one month after surgery. Immunostaining results showed that the HuNu-positive transplanted cells survived and expressed ZO1, ATP1A1 and MITF. CONCLUSION: RPE cells and CECs showed high structural and functional similarities in barrier and pump characteristics. Intracameral injection of primary RPE cells and hESC-derived RPE cells can effectively restore rabbit corneal clarity and thickness and maintain normal corneal function. This study is the first to report the effectiveness of RPE cells for corneal endothelial dysfunction, suggesting the feasibility of hESC-derived RPE cells as an equivalent substitute for CECs.

Decellularized Porcine Conjunctiva in Treating Severe Symblepharon.

This prospective study aimed to evaluate the effectiveness of decellularized porcine conjunctiva (DPC) in the management of severe symblepharon. Sixteen patients with severe symblepharon were enrolled in this study. After symblepharon lysis and Mitomycin C (MMC) application, tarsus defects were covered with residual autologous conjunctiva (AC), autologous oral mucosa (AOM), or DPC throughout the fornix, and DPC was used for all the exposed sclera. The outcomes were classified as complete success, partial success, or failure. Six symblepharon patients had chemical burns and ten had thermal burns. Tarsus defects were covered with DPC, AC, and AOM in two, three, and eleven cases, respectively. After an average follow-up of 20.0 ± 6 months, the anatomical outcomes observed were complete successes in twelve (three with AC+DPC, four with AC+AOM+DPC, and five with AOM+DPC) (75%) cases, partial successes in three (one with AOM+DPC and two with DPC+DPC) (18.75%) cases, and failure in one (with AOM+DPC) (6.25%) case. Before surgery, the depth of the narrowest part of the conjunctival sac was 0.59 ± 0.76 mm (range, 0-2 mm), tear fluid quantity (Schirmer II tests) was 12.5 ± 2.26 mm (range, 10-16 mm), and the distance of the eye rotation toward the opposite direction of the symblepharon was 3.75 ± 1.39 mm (range, 2-7 mm). The fornix depths increased to 7.53 ± 1.64 mm (range, 3-9 mm), eye movement was significantly improved, and the distance of eye movement reaching 6.56 ± 1.24 mm (range, 4-8 mm) 1 month after the operation; the postoperative Schirmer II test (12.06 ± 2.90 mm, range, 6-17 mm) was similar to that before surgery. Goblet cells were finally found in fifteen patients by conjunctival impression cytology in the transplantation area of DPC, except for one patient who failed. DPC could be considered an alternative for ocular surface reconstruction of severe symblepharon. Covering tarsal defects with autologous mucosa is necessary for extensive reconstruction of the ocular surface.

Single-cell RNA sequencing in cornea research: Insights into limbal stem cells and their niche regulation.

The corneal epithelium is composed of stratified squamous epithelial cells on the outer surface of the eye, which acts as a protective barrier and is critical for clear and stable vision. Its continuous renewal or wound healing depends on the proliferation and differentiation of limbal stem cells (LSCs), a cell population that resides at the limbus in a highly regulated niche. Dysfunction of LSCs or their niche can cause limbal stem cell deficiency, a disease that is manifested by failed epithelial wound healing or even blindness. Nevertheless, compared to stem cells in other tissues, little is known about the LSCs and their niche. With the advent of single-cell RNA sequencing, our understanding of LSC characteristics and their microenvironment has grown considerably. In this review, we summarized the current findings from single-cell studies in the field of cornea research and focused on important advancements driven by this technology, including the heterogeneity of the LSC population, novel LSC markers and regulation of the LSC niche, which will provide a reference for clinical issues such as corneal epithelial wound healing, ocular surface reconstruction and interventions for related diseases.

Effects of femtosecond laser-assisted minimally invasive lamellar keratoplasty (FL-MILK) on mild-to-moderate and advanced keratoconus.

PURPOSE: To compare the outcomes of femtosecond laser-assisted minimally invasive lamellar keratoplasty (FL-MILK) for mild-to-moderate keratoconus (KC) and advanced KC. METHODS: Prospective case series study. Sixty-three eyes of 56 patients with progressive KC underwent FL-MILK were divided into group 1 [mean keratometry (Kmean) ≤ 53D] and group 2 (Kmean > 53D). Best spectacle-corrected visual acuity (BSCVA), Kmean, maximum keratometry (Kmax), anterior central corneal elevation (ACE), stiffness parameter A1 (SP-A1) and deformation amplitude (DA) were evaluated preoperatively and up to 24 months postoperatively. RESULTS: Mean BSCVA improved from 0.34 ± 0.13 logMAR preoperatively to 0.25 ± 0.13 logMAR at 24 months postoperatively in group 1 (F = 10.10, P < .0001), and from 0.54 ± 0.31 logMAR to 0.40 ± 0.26 logMAR (F = 9.06, P = .0002) in group 2. Group 2 showed an average Kmax reduction of 10.9 D and an average Kmean reduction of 3.9 D at 24 months postoperatively (both P < .0001), whereas no significant change was observed in group 1. Average ACE decreased from 19.2 ± 10.0 to 5.2 ± 8.4 at 24 months postoperatively in group 1 (F = 28.5, P < .0001), and from 46.2 ± 16.3 to 19.1 ± 9.0 (F = 49.6, P < .0001) in group 2; SP-A1 increased from 53.8 ± 12.7 mmHg/mm to 95.9 ± 20.2 mmHg/mm in group 1 (F = 70.0, P < .0001), and from 38.6 ± 13.4 mmHg/mm to 89.3 ± 18.2 mmHg/mm (F = 96.9, P < .0001) in group 2; DA decreased from 1.30 ± 0.14 mm to 1.17 ± 0.13 mm in group 1 (F = 14.0, P < .0001), and from 1.40 ± 0.16 mm to 1.18 ± 0.10 mm (F = 27.6, P < .0001) in group 2. CONCLUSIONS: FL-MILK can stabilize progressive KC in mild-to-moderate cases and advanced cases at 24-month follow-up. Steeper corneas are more likely to undergo flattening after FL-MILK. CLINICAL TRIAL: Date of registration: July 16, 2017. The title of the trail: www. CLINICALTRIALS: gov Trial registration number: NCT03229239. The name of the trial registry: ClinicalTrials.gov.

ECM-Like Adhesive Hydrogel for the Regeneration of Large Corneal Stromal Defects.

The repair of large-diameter corneal stroma defects is a major clinical problem. Although some studies have attempted to use hydrogels to repair corneal damage, most of these hydrogels can only be used for focal stromal defects that are ≤3.5 mm in diameter due to poor hydrogel adhesion. Here, a photocurable adhesive hydrogel that mimics the extracellular matrix (ECM) with regard to composition for repairing 6 mm-diameter corneal stromal defects in rabbits is investigated. This ECM-like adhesive can be rapidly cured after light exposure, with high light transmittance and good mechanical properties. More importantly, this hydrogel maintains the viability and adhesion of cornea-derived cells and promotes their migration in vitro in 2D and 3D culture environments. Proteomics analysis confirms that the hydrogel promotes cell proliferation and ECM synthesis. Furthermore, in rabbit corneal stromal defect repair experiments, it is proven by histological and proteomic analysis that this hydrogel can effectively promote corneal stroma repair, reduce scar formation, and increase corneal stromal-neural regeneration at the six months follow-up. This work demonstrates the great application of ECM-like adhesive hydrogels for the regeneration of large-diameter corneal defects.

The senescence difference between the central and peripheral cornea induced by sutures.

INTRODUCTION: Cell senescence plays a regulatory role in tissue fibrosis. Corneal scarring is usually more severe in the central cornea based on clinical observation. In this study, we attempted to explore the senescence difference between the central and peripheral cornea in an in vivo mouse model with suture-induced senescence and in an in vitro model of senescence with hydrogen peroxide (H2O2)-induced rabbit corneal fibroblasts. METHODS: Male Balb/c mice (6-8 weeks) received sutures in the central, superior, inferior, nasal, and temporal cornea. The sutures were removed on the 14th day. Corneal neovascularization was observed under a slit lamp microscope with a digital camera. The fibroblasts isolated from the central and peripheral rabbit cornea were induced with H2O2 to establish the senescence model in vitro. Senescence was evaluated with SA-ß-gal staining and gene expression analysis of p21, p27, and p53. RESULTS: Senescent cells accumulated in the corneal stroma from the third day to the 14th day after the operation and peaked on the 14th day. More senescent keratocytes were observed in the peripheral cornea of the mouse model. In vitro, the peripheral corneal fibroblasts were more prone to senescence due to H2O2. The polymerase chain reaction results showed that the senescence-related genes p21, p27, and p53 were highly expressed in the peripheral corneal fibroblasts compared with the central corneal fibroblasts. CONCLUSIONS: Senescent fibroblasts can limit tissue fibrosis; hence, the senescence difference between the central and peripheral cornea may contribute to the difference in scarring.

SRT1720 attenuates UVA-induced corneal endothelial damage via inhibition of oxidative stress and cellular apoptosis.

Corneal endothelium is mostly sensitive to oxidative pressure and mitochondrial dysfunction. However, the oxidative-antioxidant mechanism of corneal endothelial cells (CECs) remains partially defined. Silent information regulator 1 (SIRT1) is a well-studied therapeutic target of oxidative damage. This study aimed to determine the SIRT1 expression in ultraviolet A (UVA)-induced corneal endothelial damage and explore potential drugs to repair corneal endothelial oxidative injury. In this study, we showed that CECs exhibited cellular apoptosis, reactive oxygen species (ROS) accumulation and decreased SIRT1 expression. In addition, UVA induced the imbalance of mitochondrial homeostasis and function, involving in mitochondrial membrane potential, mitochondrial fusion/fission and mitochondrial energy metabolism. SRT1720, the SIRT1 activator, effectively increased SIRT1 expression and attenuated UVA-induced oxidative damage in CECs. The therapeutic effects of SRT1720 for corneal endothelial oxidative damage were also verified in UVA-irradiated mice model. Our findings indicated that SIRT1 maintained the oxidant-antioxidant balance in corneal endothelium, suggesting a new promising therapeutic target for corneal endothelial dysfunction.

Epidemiologic characteristics and the change of surgical methods of pterygium and pseudopterygium from 2013 to 2019 in China: A retrospective analysis.

Introduction: Pterygium is a common multifactorial external eye disease, which causes various ocular symptoms and negatively affects appearance. The aim of this study was to analyze the epidemiological characteristics and the change of surgical methods of pterygium and pseudopterygium in China from 2013 to 2019. Materials and methods: This study was a hospital-based nationwide retrospective study to estimate the epidemiologic characteristics and the change of surgical methods of pterygium and pseudopteygium in China from 2013 to 2019. The data was extracted from the Hospital Quality Monitoring System (HQMS) database. The diagnosis was based on the tenth revision of the International Classification of Diseases (ICD-10) code. Results: Our study included 1,007,800 pterygium and 2,681 pseudopteygium inpatients. From 2013 to 2019, the proportion of pterygium and pseudopterygium patients who underwent surgery, among all ophthalmology inpatients, increased from 3.3% in 2013 to 7.84% in 2019. The male-female ratio of surgically treated pterygium and pseudopterygium is 1:1.8 and 1.6:1 respectively. Among all age groups, the hospitalized pterygium patients who received surgery were mainly 60-69 years old, accounting for 36.53%. The pseudopterygium patients who received surgery were mostly 50-59 years old, accounting for 24.02%. Among the 31 provinces of mainland China, Yunnan Province has the highest proportion of pterygium patients treated surgically (6.40%), while Shanghai has the highest proportion of pseudopterygium patients treated surgically (12.98%). The most common occupation of participants in the study was farmer, accounting for 47.62% and 28.53%, respectively. During the study period, the application of autologous stem cell transplantation increased year by year, and became the first choice for pterygium and pseudopterygium surgery. Discussion: This study was the first to describe the epidemiological characteristics and surgical methods of hospitalized pterygium and pseudopterygium patients in China. This study provides important information for better diagnosis, treatment and prevention of pterygium and pseudopterygium.

Should ocular Demodex be checked and treated in refractory keratitis patients without blepharitis?

AIM: To evaluate the correlation between Demodex infestation and keratitis, and to assess demodicosis using a simple approach. METHODS: A modified slit lamp illumination (at 40× magnification) was used to observe Demodex tails in 40 patients with refractory keratitis and 80 healthy controls. Bacterial smear and culture of the conjunctival sac and corneal lesion were performed to identify the pathogen. Tea tree oil ointment (TTOO) was added as a Demodex killing agent for lid scrubs to the treatment when Demodex infestation was confirmed. RESULTS: Demodex tails were found in all patients compared to 42/80 of the controls (P<0.01). Seventeen patients presented blepharitis, while 23 were free of scales and inflammation at the lid margin. The demodicosis was mild, moderate, and severe in 8, 19, and 13 patients, respectively, compared to mild in 42 controls (P<0.01). The keratitis was mild, moderate, and severe in 13, 19, and 8 patients, respectively. The severity of Demodex infestation was not correlated to the severity of keratitis (P=0.126). The growth of Staphylococcus was revealed in nine patients who did not react to antibiotic eye drops prior to the TTOO treatment. Patients' signs and symptoms got resolved after the lid scrub with TTOO. CONCLUSION: Ocular Demodex needs to be checked and treated in refractory keratitis patients with or without blepharitis. A slit-lamp illumination under high magnification favors the judgment of the severity of Demodex infestation.

Characterization and Evaluation of Rapamycin-Loaded Nano-Micelle Ophthalmic Solution.

Rapamycin-loaded nano-micelle ophthalmic solution (RAPA-NM) offers a promising application for preventing corneal allograft rejection; however, RAPA-NM has not yet been fully characterized. This study aimed to evaluate the physicochemical properties, biocompatibility, and underlying mechanism of RAPA-NM in inhibiting corneal allograft rejection. An optimized RAPA-NM was successfully prepared using a polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol (PVCL-PVA-PEG) graft copolymer as the excipient at a PVCL-PVA-PEG/RAPA weight ratio of 18:1. This formulation exhibited high encapsulation efficiency (99.25 ± 0.55%), small micelle size (64.42 ± 1.18 nm), uniform size distribution (polydispersity index = 0.076 ± 0.016), and a zeta potential of 1.67 ± 0.93 mV. The storage stability test showed that RAPA-NM could be stored steadily for 12 weeks. RAPA-NM also displayed satisfactory cytocompatibility and high membrane permeability. Moreover, topical administration of RAPA-NM could effectively prevent corneal allograft rejection. Mechanistically, a transcriptomic analysis revealed that several immune- and inflammation-related Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were significantly enriched in the downregulated genes in the RAPA-NM-treated allografts compared with the rejected allogenic corneal grafts. Taken together, these findings highlight the potential of RAPA-NM in treating corneal allograft rejection and other ocular inflammatory diseases.