Corneal epithelial defects following vitreoretinal surgery: incidence and outcomes from the DISCOVER study

AIM: To investigate the incidence, risk factors, clinical course, and outcomes of corneal epithelial defects (CED) following vitreoretinal surgery in a prospective study setting. METHODS: This was a post-hoc analysis of all participants in DISCOVER intraoperative optical coherence tomography study. Subjects with CED 1d after surgery without intraoperative corneal debridement was defined as the postoperative CED group. Subjects who underwent intraoperative debridement were defined as intraoperative debridement group. Eyes were matched 2:1 with controls (eyes without postoperative CED) for comparative assessment. The primary outcomes were the incidence of CED on postoperative day one and the incidence of required intraoperative debridement. Secondary outcomes included time to defect closure, delayed healing (>2wk), visual acuity (VA) and presence of scarring at one year and cornea consult. RESULTS: This study included 856 eyes that underwent vitreoretinal surgery. Intraoperative corneal debridement was performed to 61 (7.1%) subjects and postoperative CED developed spontaneously in 94 (11.0%) subjects. Significant factors associated with postoperative CED included prolonged surgical duration (P=0.003), diabetes mellitus (P=0.04), postoperative ocular hypotension (P<0.001). Prolonged surgical duration was associated with intraoperative debridement. Delayed defect closure time (>2wk) was associated with corneal scar formation at the end of the 1y in all epithelial defect subjects (P<0.001). The overall rate of corneal scarring for all eyes undergoing vitrectomy was 1.8%. CONCLUSION: Prolonged duration of surgery is the strongest factor associated with both intraoperative debridement and spontaneous postoperative CED. Delayed defect closure is associated with a greater risk of corneal scarring at one year. The overall rate of corneal scarring following vitrectomy is low at <2%.

Systemic Treatment of Immune-Mediated Keratoconjunctivitis Sicca with Allogeneic Stem Cells Improves the Schirmer Tear Test Score in a Canine Spontaneous Model of Disease

Keratoconjunctivitis sicca (KCS) is characterized by ocular discomfort, conjunctival hyperaemia, and corneal scarring, causing reduced aqueous tear production that can be measured using the standard Schirmer tear test (STT). Canine adipose tissue-derived MSCs (cATMSCs) have been proposed as treatment due to their anti-inflammatory effect, by releasing cytokines and immunomodulatory soluble factors. Purpose: The aim of this study was to evaluate the effect of the systemic administration of cATMSCs on tear production in dogs with immune-mediated KCS, compared to classical Cyclosporine A (CsA) treatment. Methods: Twenty-eight client-owned dogs with spontaneous KCS were allocated in the experimental group (n = 14, treated with systemic cATMSCs or control group (n = 14, treated with CsA). SST values increased significantly at days 15 (p = 0.002), 45 (p = 0.042) and 180 (p = 0.005) with no observed side-effects in the experimental group. Eyes with an initial STT value of 11–14 mm/min maintained significant improvement at day 180, needing only artificial tears as treatment. Eyes with an initial STT value <11 mm/min needed cyclosporin treatment at day 45, so follow-up was stopped. Control animals treated with CsA did not improve their STT at day 180. Results and Conclusions: Systemic allogeneic cATMSCs application appeared to be a feasible and effective therapy with positive outcome in dogs with initial STT between 11–14 mm/min, with a significant improvement in tear production. The STT increment was maintained for at least 180 days, without needing additional medication, thus suggesting it could constitute an alternative therapy to classical immunosuppressive treatments.

HSV-1 small non-coding RNA (sncRNA) 1 and 2 activate the Herpes virus entry mediator (HVEM) promoter

HSV-1 latency associated transcript (LAT) plays a significant role in efficient establishment of latency and reactivation. LAT has antiapoptotic activity and downregulates expression of components of the Type I interferon pathway. LAT also specifically activates expression of the herpesvirus entry mediator (HVEM), one of seven known receptors used by HSV-1 for cell entry that is crucial for latency and reactivation. However, the mechanism by which LAT regulates HVEM expression is not known. LAT encodes two sncRNAs that are not miRNAs, within its 1.5 kb stable transcript, which also have antiapoptotic activity. These sncRNAs may encode short peptides, but experimental evidence is lacking. Here, we demonstrate that these two sncRNAs control HVEM expression by activating its promoter. Both sncRNAs are required for WT level of activation of HVEM and sncRNA1 is more important in HVEM activation than sncRNA2. Disruption of a putative start codon in sncRNA1 and sncRNA2 sequences reduced HVEM promoter activity, suggesting that sncRNAs may encode a protein. However, we did not detect peptide binding using two chromatin immunoprecipitation (ChIP) approaches and a web-based algorithm predicts low probability that the putative peptides bind to DNA. In addition, computational modeling predicts that sncRNA molecules bind with high affinity to the HVEM promoter and deletion of these binding sites to sncRNA1, sncRNA2 or both reduced HVEM promoter activity. Together, our data suggests that sncRNAs exert their function as RNA molecules, not as proteins, and we provide a model for the predicted binding affinities and binding sites of sncRNA1 and sncRNA2 in the HVEM promoter. IMPORTANCE HSV-1 causes recurrent ocular infections, which is the leading cause of corneal scarring and blindness. Corneal scarring is caused by the host immune response to repeated reactivation events. LAT functions by regulating latency and reactivation, in part by inhibiting apoptosis and activating HVEM expression. However, the mechanism used by LAT to control of HVEM expression is unclear. Here, we demonstrate that two sncRNAs encoded within the 1.5 kb LAT transcript activate HVEM expression by binding to two regions of its promoter. Interfering with these interactions may reduce latency and thereby eye disease associated with reactivation.

Polymicrobial keratitis after accelerated corneal collagen cross-linking in keratoconus: Case reports and literature review

Purpose To report two cases of polymicrobial keratitis following corneal collagen cross-linking for keratoconus and to review the literature. Methods Retrospective case note and literature review. Results The first case involved a 27-year-old male who presented with amebic corneal ulcers 3 days after the collagen cross-linking procedure. Some gram-negative (gram-ve) cocci were found upon staining, and cysts were observed by confocal microscopy at 7 days after surgery. Acanthamoeba infection mixed with gram-ve organisms was diagnosed. In the second case, a 14-year male developed Staphylococcus aureus corneal infection with anterior chamber empyema 3 days after the collagen cross-linking procedure for keratoconus. Occasional gram-positive (gram + ve) cocci and gram-ve bacilli were observed under a microscope. The mixed keratitis in the two patients resolved after systemic and topical antibiotic therapy, but the infection ultimately resulted in corneal scarring. Follow-up keratoplasty was needed to improve vision acuity in both patients. Conclusion Although ultraviolet irradiation and the reactive oxygen released by riboflavin during collagen cross-linking have bactericidal effects, a lack of a corneal epithelial barrier, bandage contact lens usage, perioperative hygiene, and an abnormal immune state are risk factors for infectious keratitis after collagen cross-linking. Perioperative management of collagen cross-linking is important to prevent infection.

Herpetic Keratitis Preceded by COVID-19 Vaccination

The global Coronavirus Disease 2019 (COVID-19) pandemic has accelerated vaccine development at an unprecedented rate. A large population of people have received COVID-19 vaccines, while the vaccine safety data are limited. Here, we reported two cases of herpetic keratitis that occurred soon after receiving the inactivated COVID-19 vaccines. Case 1 was a 60-year-old woman who underwent penetrating keratoplasty (PKP) one year ago for corneal scarring caused by herpes simplex keratitis (HSK), and case 2 was a 51-year-old man with an unremarkable medical history. Both patients developed herpetic keratitis (HSK and varicella-zoster virus corneal endotheliitis, respectively) soon after receiving the inactivated COVID-19 vaccines (Sinovac). Herpetic keratitis was treated successfully with topical or plus oral antiviral ganciclovir. The short latency time in these two cases suggested that an inactivated COVID-19 vaccine may have a risk of triggering ocular herpes virus reactivation. Both clinicians and patients should be aware of this phenomenon. However, a causal relationship awaits confirmation.

FAK Inhibition Attenuates Corneal Fibroblast Differentiation In Vitro

Corneal fibrosis (or scarring) occurs in response to ocular trauma or infection, and by reducing corneal transparency, it can lead to visual impairment and blindness. Studies highlight important roles for transforming growth factor (TGF)-β1 and -β3 as modulators in corneal wound healing and fibrosis, leading to increased extracellular matrix (ECM) components and expression of α-smooth muscle actin (αSMA), a myofibroblast marker. In this study, human corneal fibroblasts (hCF) were cultured as a monolayer culture (2D) or on poly-transwell membranes to generate corneal stromal constructs (3D) that were treated with TGF-β1, TGF-β3, or TGF-β1 + FAK inhibitor (FAKi). Results show that hCF 3D constructs treated with TGF-β1 or TGF-β3 impart distinct effects on genes involved in wound healing and fibrosis—ITGAV, ITGB1, SRC and ACTA2. Notably, in the 3D construct model, TGF-β1 enhanced αSMA and focal adhesion kinase (FAK) protein expression, whereas TGF-β3 did not. In addition, in both the hCF 2D cell and 3D construct models, we found that TGF-β1 + FAKi attenuated TGF-β1-mediated myofibroblast differentiation, as shown by abrogated αSMA expression. This study concludes that FAK signaling is important for the onset of TGF-β1-mediated myofibroblast differentiation, and FAK inhibition may provide a novel beneficial therapeutic avenue to reduce corneal scarring.

Double-masked, sham and placebo-controlled trial of corneal cross-linking and topical difluprednate in the treatment of bacterial keratitis: Steroids and Cross-linking for Ulcer Treatment Trial (SCUT II) study protocol

IntroductionAlthough antibiotics are successful at achieving microbiological cure in infectious keratitis, outcomes are often poor due to corneal scarring. Ideal treatment of corneal ulcers would address both the infection and the inflammation. Adjunctive topical steroid treatment may improve outcomes by reducing inflammation. Corneal cross-linking (CXL) is a novel prospective therapy that may simultaneously reduce both inflammatory cells and bacterial pathogens. The purpose of this study is to determine differences in 6-month visual acuity between standard medical therapy with antibiotics versus antibiotics with adjunctive early topical steroid therapy versus antibiotic treatment plus CXL and early topical steroids.Methods and analysisThis international, randomised, sham and placebo-controlled, three-arm clinical trial randomises patients with smear positive bacterial ulcers in a 1:1:1 fashion to one of three treatment arms: (1) topical 0.5% moxifloxacin plus topical placebo plus sham CXL; (2) topical 0.5% moxifloxacin plus difluprednate 0.05% plus sham CXL; or (3) the CXL group: topical 0.5% moxifloxacin plus difluprednate 0.05% plus CXL.Ethics and disseminationWe anticipate that both adjunctive topical steroids and CXL will improved best spectacle corrected visual acuity and also reduce complications such as corneal perforation and the need for therapeutic penetrating keratoplasty. This study will comply with the NIH Data Sharing Policy and Policy on the Dissemination of NIH-Funded Clinical Trial Information and the Clinical Trials Registration and Results Information Submission rule. Our results will be disseminated via ClinicalTrials.gov website, meetings and journal publications. Our data will also be available on reasonable request.Trial registration numberNCT04097730.

Complicated corneal ulceration in cats: diagnosis and treatment outcomes of 80 cases (2014-2018)

The study describes the most common clinical and endoscopic findings associated with complicated corneal ulcers in cats and evaluates the short-term outcomes after surgical interventions. Eighty client-owned cats of different breeds with corneal ulcers were included. Cats were clinically evaluated to initially determine corneal abnormalities. Endoscopic examination of the corneas was performed to determine anterior and posterior segments’ abnormalities. Non-healing superficial ulcer was treated by superficial keratectomy and deep stromal ulcers were treated using conjunctival flaps. Corneal sequestrum were treated by partial keratectomies and conjunctival flaps. Anterior synechiae were treated via peripheral iridectomy and separation of the adhesion between the iris and the inner cornea. Symblepharon were treated by removal of the adhered conjunctival membrane from the cornea. Unresponsive endophthalmitis was treated surgically by exenteration. Outcomes after surgical managements of selected corneal abnormalities were assessed clinically and endoscopically. Non-healing superficial ulcer, deep stromal ulcer with descemetocele, endophthalmitis, symblepharon, corneal sequestration and anterior synechiae with secondary glaucoma and corneal scarring were the recorded complications of corneal ulcer. FHV-1 was a common etiologic factor of corneal ulceration. Persistent corneal scars of varying shape and size developed in cats with deep stromal ulcer, anterior synechiae, and corneal sequestration. Domestic shorthaired and Persian cats were the most predisposed breeds to FHV-1 infection and subsequent corneal ulceration. Management of patients with corneal ulcer would prevent serious complications. No age or sex predisposition to complicated corneal ulceration in cats was noticed.

Dextran Sulfate Polymer Wafer Promotes Corneal Wound Healing

Eye injuries due to corneal abrasions, chemical spills, penetrating wounds, and microbial infections cause corneal scarring and opacification that result in impaired vision or blindness. However, presently available eye drop formulations of anti-inflammatory and antibiotic drugs are not effective due to their rapid clearance from the ocular surface or due to drug-related side effects such as cataract formation or increased intraocular pressure. In this article, we presented the development of a dextran sulfate-based polymer wafer (DS-wafer) for the effective modulation of inflammation and fibrosis and demonstrated its efficacy in two corneal injury models: corneal abrasion mouse model and alkali induced ocular burn mouse model. The DS-wafers were fabricated by the electrospinning method. We assessed the efficacy of the DS-wafer by light microscopy, qPCR, confocal fluorescence imaging, and histopathological analysis. These studies demonstrated that the DS-wafer treatment is significantly effective in modulating corneal inflammation and fibrosis and inhibited corneal scarring and opacification compared to the unsulfated dextran-wafer treated and untreated corneas. Furthermore, these studies have demonstrated the efficacy of dextran sulfate as an anti-inflammatory and antifibrotic polymer therapeutic.

Corneal epithelial mapping in different corneal conditions

Background Cataract surgery is traumatic to the corneal epithelium,scarring and opacity is the commonest cause of blindness. Objective To study the corneal epithelial thickness in different corneal conditions using anterior segment optical coherence tomography (AS-OCT). Patients and Methods A case-control study including 80 eyes divided equally into 4 groups; group 1:controls,group 2:corneal scarring ,group 3:cataract patients and group 4:pterygium. using AS-OCT epithelial mapping to document changes in epithelial thickness in controls, cataract patients pre and 1 month after phacoemulsification, patients with corneal scarring and patients with pterygium. Results In phacoemulsification group; we found that epithelial thickness became thinner in area (0_2) and thicker in area (7_9) mm in the map with no significant change in areas (2_5),(5_7) mm in the map. In corneal scarring group; we found that epithelial thickness became thicker compared to control group in all zones. In pterygium group; we found that epithelial thickness became thicker compared to control group in, areas (2_5), (5_7) & (7_9) mm in the map with no significant change in area (0_2) mm in the map. Conclusion The corneal epithelium thickness becomes thinner or thicker to compensate for changes in stromal thickness.