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.

Repeatability assessment of anterior segment measurements in myopic patients using an anterior segment OCT with placido corneal topography and agreement with a swept-source OCT.

BACKGROUND: The precision of anterior segment biometric measurements in eyes has become increasingly important in refractive surgery. The purpose of this study is to assess the repeatability of the automatic measurements provided by a new spectral-domain optical coherence tomograph (SD-OCT)/Placido topographer (MS-39, CSO) and its agreement with a swept-source OCT (SS-OCT) biometer (CASIA SS-1000, Tomey) in patients with myopia. METHODS: The right eye of 235 subjects was scanned 3 times with both devices. The evaluated parameters included central corneal radius of the steep meridian, central corneal radius of the flat meridian, mean central corneal radius, thinnest corneal thickness, central corneal thickness, anterior chamber depth, corneal volume and diameter. The intraobserver repeatability of the MS-39 measurements was calculated using intraclass correlation coefficient (ICC), within subject standard deviation, coefficient of repeatability, coefficient of variation and repeated-measures analysis of variance of the 3 repeated measurements. The agreement between the two devices was evaluated by 95% limits of agreement (LoA). RESULTS: The majority of the parameters acquired from MS-39 showed high repeatability. The repeatability of corneal diameter was slightly lower than the other measurements, although the ICC remained high. Agreement with the CASIA SS-1000 was good, indicated by the Bland-Altman plots with narrow 95% LoA values for all parameters assessed. CONCLUSIONS: The high repeatability of automatic measurements by the new device supports its clinical application in eyes with myopia, and the good agreement between the two devices indicates they could be used interchangeably for the parameters evaluated.

Long-term dynamic changes and influencing factors of corneal morphology after multiple intravitreal injections of anti-VEGF drugs.

To observe alterations in corneal morphology caused by repeated intravitreal injections of anti-vascular endothelial growth factor (VEGF). Prospective cohort study. Seventy-seven eyes were treated with intravitreal injection of anti-VEGF from June 2021 to March 2023. There were 25 eyes of neovascular age-related macular degeneration (nAMD), 24 eyes of diabetic macular edema (DME), and 28 eyes of retinal vein occlusion (RVO). Aflibercept was used in 37 eyes and Ranibizumab was used in 40 eyes. 3 + PRN was used. Corneal endothelium and corneal thickness were measured using a corneal endothelial microscope. The data related to central corneal thickness, corneal endothelial cell density (ECD), average cell size, coefficient of variation (CV), proportion of hexagonal cells (Hex%) was collected. A comparison was also made between baseline and the dynamic changes of all indexes 1 year following the last injection. It was observed that in comparison to baseline, ECD and Hex% decreased significantly after the 3rd injection of Aflibercept and Ranibizumab. However, ECD did not decrease further and remained at the same level as after the last injection. Hex% and average cell size increased to a certain extent in comparison to the last injection. All the changes were found to be statistically significant (P < .01). After 3 injections, ECD in DME group was markedly lower than that in nAMD and RVO group, but the CV in DME group was higher than that in nAMD as well as RVO groups, and all the differences were statistically significant (P < .05). Following intravitreal anti-VEGF therapy, DME is more likely than other disorders to result in a decrease in ECD. Repeated intravitreal injections of anti-VEGF drugs can reduce the Hex% and ECD to a certain extent. After the last injection, Hex% can progressively recover, and ECD can remain stable without further declining. After injections, ECD in DME group was found to be significantly lower than that in nAMD and RVO groups, but CV in DME group was significantly higher in comparison to the other 2 groups. In patients with macular edema, repeated intravitreal injections of anti-VEGF may have certain effects on corneal morphology. Patients with diabetes mellitus in particular should pay special attention to corneal safety following repeated intravitreal injections if they have significantly reduced ECD at baseline.

Associations between corneal curvature and other anterior segment biometrics in young myopic adults.

To investigate the associations between corneal curvature (CC) and other anterior segment biometrics in young myopic adults. In this retrospective multi-center study, 7893 young myopic adults were included. CC and other anterior segment biometrics were measured by Scheimpflug imaging (Pentacam). CC was defined as SimK at central 3 mm area, and other anterior segment biometrics included white-to-white corneal diameter (WTW), central corneal thickness (CCT), corneal volume (CV) at 3 mm, 5 mm, and 7 mm area, anterior corneal astigmatism (ACA), posterior corneal astigmatism (PCA), anterior corneal eccentricity (ACE) and asphericity (ACAP), posterior corneal eccentricity (PCE) and asphericity (PCAP), anterior chamber depth (ACD), and anterior chamber volume (ACV). Univariate regression analyses were used to assess the associations between CC and other anterior segment biometrics, and multivariate regression analyses were further performed to adjusted for age, gender and spherical equivalent. CC was higher in patients of female gender and higher myopia (all P < 0.05). Eyes in higher CC quartiles had lower WTW, thinner CCT, lower CV at 3 mm and 5 mm, lower ACD, and lower ACV (all P < 0.001), but had larger ACA, larger PCA, less PCE and less PCAP (all P < 0.001), compared to eyes in lower CC quartiles. The trends of CV at 7 mm, ACE and ACAP were inconsistent in different CC quartiles. After adjusting for age, gender and spherical equivalent with multivariate linear regression, CC was positively correlated to CV at 7 mm (ßs = 0.069), ACA (ßs = 0.194), PCA (ßs = 0.187), ACE (ßs = 0.072), PCAP (ßs = 0.087), and ACD (ßs = 0.027) (all P < 0.05), but was negatively correlated to WTW (ßs = - 0.432), CCT (ßs = - 0.087), CV-3 mm (ßs = - 0.066), ACAP (ßs = - 0.043), PCE (ßs = - 0.062), and ACV (ßs = - 0.188) (all P < 0.05). CC was associated with most of the other anterior segment biometrics in young myopic adults. These associations are important for better understanding of the interactions between different anterior segment structures in young myopic patients, and are also useful for the exploration of the pathogenesis of myopia.

Exosomal microRNAs as potential biomarkers and therapeutic targets in corneal diseases.

Exosomes are a subtype of extracellular vesicle (EV) that are released and found in almost all body fluids. Exosomes consist of and carry a variety of bioactive molecules, including genetic information in the form of microRNAs (miRNAs). miRNA, a type of small non-coding RNA, plays a key role in regulating genes by suppressing their translation. miRNAs are often disrupted in the pathophysiology of different conditions, including eye disease. The stability and easy detectability of exosomal miRNAs in body fluids make them promising biomarkers for the diagnosis of different diseases. Additionally, due to the natural delivery capabilities of exosomes, they can be modified to transport therapeutic miRNAs to specific recipient cells. Most exosome research has primarily focused on cancer, so there is limited research highlighting the importance of exosomes in ocular biology, particularly in cornea-associated pathologies. This review provides an overview of the existing evidence regarding the primary functions of exosomal miRNAs and their potential role in diagnostic and therapeutic applications in the human cornea.

Formononetin protects against Aspergillus fumigatus Keratitis: Targeting inflammation and fungal load.

PURPOSE: To investigate the potential treatment of formononetin (FMN) on Aspergillus fumigatus (A. fumigatus) keratitis with anti-inflammatory and antifungal activity. METHODS: The effects of FMN on mice with A. fumigatus keratitis were evaluated through keratitis clinical scores, hematoxylin-eosin (HE) staining, and plate counts. The expression of pro-inflammatory factors was measured using RT-PCR, ELISA, or Western blot. The distribution of macrophages and neutrophils was explored by immunofluorescence staining. The antifungal properties of FMN were assessed through minimum inhibitory concentration (MIC), propidium iodide (PI) staining, fungal spore adhesion, and biofilm formation assay. RESULTS: In A. fumigatus keratitis mice, FMN decreased the keratitis clinical scores, macrophages and neutrophils migration, and the expression of TNF-α, IL-6, and IL-1ß. In A. fumigatus-stimulated human corneal epithelial cells (HCECs), FMN reduced the expression of IL-6, TNF-α, IL-1ß, and NLRP3. FMN also decreased the expression of thymic stromal lymphopoietin (TSLP) and thymic stromal lymphopoietin receptor (TSLPR). Moreover, FMN reduced the levels of reactive oxygen species (ROS) induced by A. fumigatus in HCECs. Furthermore, FMN inhibited A. fumigatus growth, prevented spore adhesion and disrupted fungal biofilm formation in vitro. In vivo, FMN treatment reduced the fungal load in mice cornea at 3 days post infection (p.i.). CONCLUSION: FMN demonstrated anti-inflammatory and antifungal properties, and exhibited a protective effect on mouse A. fumigatus keratitis.

Comparative posterior corneal profile of keratoconus hydrops versus Haab's striae in congenital glaucoma.

Keratoconus eyes develop corneal decompensation more often compared to eyes with primary congenital glaucoma (PCG) following Descemet's membrane (DM) tear. This study was conducted to compare the posterior corneal morphology in areas with DM breaks with regards to DM and pre-Descemet's layer (PDL) between the two. In this cross-sectional comparative study, anterior segment optical coherence tomography (AS-OCT) scans of the posterior cornea of advanced keratoconus eyes with hydrops ( n = 12), PCG eyes with Haab's striae ( n = 15), and healthy control eyes ( n = 14) were compared for DM-PDL morphology. These were further corroborated by the histopathology of corneal buttons from keratoconus ( n = 14) and PCG ( n = 13) cases obtained following penetrating keratoplasty and compared with controls (enucleated retinoblastoma globes, n = 6) on light microscopy and collagen IV immunostaining. AS-OCT showed a thicker median DM/PDL complex in PCG (80 µm) versus keratoconus eyes (36 µm, P = 0.01; Kruskal-Wallis test). The median height and length of detached DM-PDL were significantly more in keratoconus versus PCG (145 µm, 1766.1 ± 1320.6 µm vs. 26.5 µm, 453.3 ± 303.2 µm, respectively, P = 0.012; Kruskal-Wallis test). Type-1 DM/PDL detachment (seen as a characteristic taut chord) in keratoconus (90%) was the most common morphological pattern versus intracameral twin protuberance (92%) following DM breaks in PCG. Histopathology confirmed thicker DM in PCG (median: 63.4 µm) versus keratoconus eyes (median: 33.2 µm) or controls (27.1 µm) ( P = 0.001; Kruskal-Wallis test). Greater height/length of DM/PDL detachment compounded by poor healing response (lower DM/PDL thickness) probably causes more frequent corneal decompensation in keratoconus eyes when compared to PCG eyes following DM tears.

Use of In Vivo Corneal Confocal Microscopy to Guide Excimer Laser With Adjunctive Mitomycin C for Treatment of Recalcitrant Acanthamoeba Keratitis.

PURPOSE: The aim of this study was to describe 3 cases of recalcitrant Acanthamoeba keratitis (AK) that were successfully treated using in vivo corneal confocal microscopy (IVCM) to guide excimer laser ablation depth with adjunctive mitomycin C 0.02%. METHODS: Three patients diagnosed with AK did not respond to several weeks of intensive topical therapy with antiamoebic agents. The patient underwent phototherapeutic keratectomy with topical mitomycin C 0.02% application. The maximum stromal depth of cysts measured by IVCM was 80 µm, 100 µm, and 240 µm, and the stromal ablation depths were 80 µm, 100 µm, and 100 µm, respectively. RESULTS: In all 3 eyes, AK resolved after a single excimer laser application, and topical treatment was gradually discontinued within 6 weeks afterward. In 1 eye, penetrating corneal transplantation was performed 6 weeks after phototherapeutic keratectomy because of ongoing severe corneal pain. IVCM and histology of the corneal transplant did not reveal any Acanthamoeba cysts within the excised corneal button. No recurrence was observed during the follow-up period of 19 to 34 months. CONCLUSIONS: IVCM-guided phototherapeutic keratectomy with mitomycin C 0.02% seems to be a safe and successful approach for the treatment of AK, especially in cases of resistance to topical treatment. Corneal IVCM should be performed before laser application to measure cyst depth, determine ablation depth, and assess postoperative treatment success.

A method for teaching depth of corneal lesions using a portable slit lamp (biomicroscope).

A novel, simple, and inexpensive model for teaching depth of lesions within the cornea using slit lamp biomicroscopy to veterinary students, ophthalmology residents, and general clinicians with access to a slit lamp biomicroscope is described. Using common laboratory items, this method can be created in any clinic and can be used to teach and quiz students through independent study with objective self-testing achieved.

Tissue-targeted and localized AAV5-DCN and AAV5-PEDF combination gene therapy abrogates corneal fibrosis and concurrent neovascularization in rabbit eyes in vivo.

PURPOSE: Corneal fibrosis and neovascularization (CNV) after ocular trauma impairs vision. This study tested therapeutic potential of tissue-targeted adeno-associated virus5 (AAV5) mediated decorin (DCN) and pigment epithelium-derived factor (PEDF) combination genes in vivo. METHODS: Corneal fibrosis and CNV were induced in New Zealand White rabbits via chemical trauma. Gene therapy in stroma was delivered 30-min after chemical-trauma via topical AAV5-DCN and AAV5-PEDF application using a cloning cylinder. Clinical eye examinations and multimodal imaging in live rabbits were performed periodically and corneal tissues were collected 9-day and 15-day post euthanasia. Histological, cellular, and molecular and apoptosis assays were used for efficacy, tolerability, and mechanistic studies. RESULTS: The AAV5-DCN and AAV5-PEDF combination gene therapy significantly reduced corneal fibrosis (p < 0.01 or p < 0.001) and CNV (p < 0.001) in therapy-given (chemical-trauma and AAV5-DCN + AAV5-PEDF) rabbit eyes compared to the no-therapy given eyes (chemical-trauma and AAV5-naked vector). Histopathological analyses demonstrated significantly reduced fibrotic α-smooth muscle actin and endothelial lectin expression in therapy-given corneas compared to no-therapy corneas on day-9 (p < 0.001) and day-15 (p < 0.001). Further, therapy-given corneas showed significantly increased Fas-ligand mRNA levels (p < 0.001) and apoptotic cell death in neovessels (p < 0.001) compared to no-therapy corneas. AAV5 delivered 2.69 × 107 copies of DCN and 2.31 × 107 copies of PEDF genes per µg of DNA. AAV5 vector and delivered DCN and PEDF genes found tolerable to the rabbit eyes and caused no significant toxicity to the cornea. CONCLUSION: The combination AAV5-DCN and AAV5-PEDF topical gene therapy effectively reduces corneal fibrosis and CNV with high tolerability in vivo in rabbits. Additional studies are warranted.

Self-complementary AAV vector therapy for treating corneal cloudiness of mucopolysaccharidosis type VII (MPS VII).

PURPOSE: To design a novel efficacious scAAV-Gusb viral vector for treating Mucopolysaccharidosis Type VII (MPS VII) caused by a mutation in the ß-Glu gene (Gusb allele). METHODS: ß-Glu expression of single-stranded AAV-Gusb (ssAAV-Gusb) and self-complementary AAV (scAAV-Gusb) vectors are tested with cultured murine Gusb fibroblasts. The scAAV-Gusb vector was chosen in further studies to prolong the life span and treat corneal pathology of Gusb mice via intrahepatic injection of neonates and intrastromal injection in adults, respectively. Corneal pathology was studied using HRT2 in vivo confocal microscope and histochemistry in mice corneas. RESULTS: Both ssAAV-Gusb and scAAV-Gusb vectors expressed murine ß-Glu in cultured Gusb fibroblasts. The scAAV-Gusb vector had higher transduction efficiency than the ssAAV-Gusb vector. To prolong the life span of Gusb mice, neonates (3 days old) were administered with scAAV-Gusb virus via intrahepatic injection. The treatment improves the survival rate of Gusb mice, prolonging the median survival rate from 22.5 weeks (untreated) to 50 weeks (treated). Thereafter, we determined the efficacy of the scAAV-Gusb virus in ameliorating corneal cloudiness observed in aged Gusb mice. Both corneal cloudiness and stroma thickness decreased, and there was the presence of ß-Glu enzyme activity in the Gusb corneas receiving scAAV-Gusb virus associated with morphology change of amoeboid stromal cells in untreated to characteristic dendritic keratocytes morphology after 4-12 weeks of scAAV-Gusb virus injection. CONCLUSION: Intrahepatic injection of scAAV-Gusb is efficacious in prolonging the life span of Gusb mice, and intrastromal injection can ameliorate corneal phenotypes. Both strategies can be adapted for treating other MPS.

Xanthogranulomatous keratitis in a mixed-breed dog.

OBJECTIVE: To evaluate the clinical and histopathological features of a case of xanthogranulomatous keratitis in a mixed-breed dog. ANIMAL: Mixed-breed dog. CLINICAL PRESENTATION, PROGRESSION, AND PROCEDURES: An 11-year-old spayed female mixed-breed dog was presented for mild blepharospasm, corneal cloudiness, and increasing conjunctival hyperemia OD. Ophthalmic examination revealed multifocal pink and cream-colored consolidated corneal infiltrative lesions and generalized neovascularization with suspected diagnosis of stromal abscessation. There was no improvement after 1 month of medical management, so a keratectomy was performed, and corneal tissue was sent for histopathological evaluation. TREATMENT AND OUTCOME: The nonulcerative keratitis was refractive to medical management including topical and systemic antibiotics, topical antifungal, and systemic anti-inflammatory, so keratectomy was performed. Histopathologic diagnosis of xanthogranulomatous keratitis was made 1 week postoperatively. The patient was prescribed 0.05% difluprednate ophthalmic emulsion and 0.2% tacrolimus ophthalmic ointment (initially q 8 h, OD). The difluprednate was tapered and discontinued after 2 months, but the tacrolimus was continued (q 12 h, OD). No lesion recurrence had been documented 1 year postoperatively. CLINICAL RELEVANCE: There has been little published on canine xanthogranulomas, especially in veterinary ophthalmology. Ocular xanthogranulomas have been reportedly found intraocularly and at the ocular surface. Histologically, they are characterized by well-delineated nodules that contain histiocytes and abundant lipid-laden macrophages. The treatment in this clinical case was surgical excision followed with topical immunosuppression/anti-inflammatory therapy with no recurrence 1 year postoperatively. Xanthogranulomatous keratitis should be an added differential diagnosis when nonulcerative keratitis is found on examination, specifically with consolidated, corneal infiltrate and minimal pain.

Short chain fatty acids inhibit corneal inflammatory responses to TLR ligands via the ocular G-protein coupled receptor 43.

PURPOSE: Short chain fatty acids (SCFAs) produced by gut microbiota are known to play primary roles in gut homeostasis by immunomodulation partially through G-protein coupled receptors (GPR) 43. Using mouse models of TLR ligand induced keratitis, we investigated whether SCFAs and GPR43 play any regulatory roles in the pathogenesis of inflammatory responses in the eye. METHODS: Both human and mouse eyes were labeled with a specific antibody for GPR43 and imaged by a laser scanning confocal microscope. Corneal cups from naïve C57BL/6J (B6) and GPR43 knockout (KO) mice were stimulated with TLR ligands in the presence or absence of sodium butyrate overnight and then processed for RT-PCR assay for expression of GPR43 and cytokines. Keratitis was induced by Poly I:C in wild type (WT) B6, GPR43KO and chimeric mice and the disease severity was evaluated by the corneal fluorescein staining test, and infiltrating cell staining and calculating in corneal whole mount. RESULTS: GPR43 is expressed in both human and mouse eyes and the expression is bidirectionally regulated by TLR ligands and butyrate. Butyrate significantly inhibited inflammation caused by several TLR ligands such as Poly I:C, Flagellin, and CpG-ODN (TLR-3, 5 and 9 agonists, respectively) in WT, but not GPR43KO, mice. Butyrate inhibition of TLR-induced keratitis is mediated by the GPR43 expressed in tissue but not hematopoietic, cells. CONCLUSIONS: This is the first report to demonstrate of the protective effect of SCFAs on microbial keratitis, and the dynamic expression and anti-inflammatory function of GPR43 in the eye. SCFAs can modulate inflammation and immunity in the eye through GPR43.

Corneal Epithelial Development and the Role of Induced Pluripotent Stem Cells for Regeneration.

Severe corneal disorders due to infective aetiologies, trauma, chemical injuries, and chronic cicatricial inflammations, are among vision-threatening pathologies leading to permanent corneal scarring. The whole cornea or lamellar corneal transplantation is often used as a last resort to restore vision. However, limited autologous tissue sources and potential adverse post-allotransplantation sequalae urge the need for more robust and strategic alternatives. Contemporary management using cultivated corneal epithelial transplantation has paved the way for utilizing stem cells as a regenerative potential. Humaninduced pluripotent stem cells (hiPSCs) can generate ectodermal progenitors and potentially be used for ocular surface regeneration. This review summarizes the process of corneal morphogenesis and the signaling pathways underlying the development of corneal epithelium, which is key to translating the maturation and differentiation process of hiPSCs in vitro. The current state of knowledge and methodology for driving efficient corneal epithelial cell differentiation from pluripotent stem cells are highlighted.

Potential Benefits of Integrin αvß3 Antagonists in a Mouse Model of Experimental Dry Eye.

PURPOSE: The purpose of this study was to extensively evaluate the efficacy of integrin αvß3 antagonists for the treatment of experimental dry eye (EDE). METHODS: Vitronectin, an αvß3 ligand, was used to induce tumor necrosis factor-α gene expression in human THP-1 macrophages. To induce EDE, C57BL/6 mice were housed in a low-humidity controlled environment chamber and injected subcutaneously with scopolamine for 7 days. Subsequently, αvß3 antagonists, including RGDfD, c(RGDfD), c(RGDiD), c(RGDfK), ATN-161, SB273005, and cilengitide, were administered topically to EDE animals under controlled environment chamber conditions. Corneal epithelial damage in EDE was assessed by fluorescein staining. The density of conjunctival goblet cells and secretion of tears was measured by period acid-Schiff staining and phenol red-impregnated cotton threads, respectively. Inflammation markers, including tumor necrosis factor-α, interleukin (IL)-1ß, IL-6, IL-17A, and metalloproteinase (MMP)-9, in the pooled cornea and conjunctiva tissues were examined by real-time polymerase chain reaction. RESULTS: The inhibitory effects of αvß3 antagonists on the vitronectin-induced tumor necrosis factor-α gene expression and integrin-mediated inflammatory signaling were validated in THP-1 macrophages. αvß3 antagonists ameliorated the impairment of the corneal epithelial barrier with varying therapeutic efficacies, compared with vehicle-treated mice. c(RGDfD) and c(RGDiD) significantly protected against goblet cell loss, tear reduction, and proinflammatory gene expression in EDE. CONCLUSIONS: Topical applications of αvß3 antagonists yield therapeutic benefits in EDE by promoting corneal epithelial defect healing and reducing inflammation. Antagonistic targeting αvß3 may be a novel promising strategy to treat patients with dry eye disease.

Suitability of Slaughterhouse-Acquired Pig Eyes as Model Systems for Refractive Ultraviolet and Infrared Femtosecond Laser Research.

PURPOSE: To elucidate whether it is feasible to use porcine eyes from scalded, abattoir-acquired animals for refractive femtosecond laser research. METHODS: An infrared laser (FS 200) and an ultraviolet laser (prototype version) were tested for their applicability on scalded pig eyes. Fifty porcine eyes were divided into two equally-sized groups and assigned to either the infrared or the ultraviolet laser. Both laser groups were comprised of five subgroups of n = 5 eyes each. Group A: non-scalded eyes (negative control); group B: eyes taken from tunnel-scalded animals; group C1: eyes taken from tank-scalded animals without opaque corneal lesion; group C2: eyes taken from animals with opaque corneal lesion; group D: eyes scalded in toto in the laboratory (positive control). In each group the lasers were employed to create a stromal flap. The quality of the laser cuts and the resulting flap beds, as well as of the porcine corneas themselves, was examined by anterior segment optical coherence tomography and scanning electron microscopy. RESULTS: All scalded specimens exhibited substantial corneal swelling, most pronounced in group C2. After ultraviolet laser application, the tank- and tunnel-scalded samples displayed marked irregularities and an increased degree of surface roughness in the flap beds. After infrared laser application, this was only the case in the tank-scalded specimens. CONCLUSION: It is not recommended to use eyes taken from scalded pigs for ultraviolet femtosecond laser experiments. For infrared femtosecond lasers, eyes taken from tunnel-scalded animals may represent an acceptable alternative, if non-scalded eyes are not available.

The role of corneal biopsy in the management of microbial keratitis.

PURPOSE: Corneal biopsy helps in diagnosing deep-seated or recalcitrant lesions of microbial keratitis (MK). We aim to analyze its role in managing these challenging cases. METHODS: This is a retrospective review of 22 cases of corneal biopsy at our institute from January 2010 to December 2021. Data were retrospectively collected using the electronic medical record (EMR) system. Those cases of indolent, progressive MK or deep-seated lesions where cornea scraping was not possible were considered for corneal biopsy to establish the microbiological diagnosis. The primary aims of our study were to analyze the indications, success rates, and outcomes for biopsy patients in our series. Additional outcomes that were analyzed included the average time from presentation to biopsy, the type of causative organism isolated from the biopsy by either histopathological or microbiological method, and the frequency and outcome of surgical interventions performed. Descriptive statistics using mean (±standard deviation) and median (±range) were used to interpret the demographic data. RESULTS: Overall, 15 of 22 patients (68%) had a positive corneal biopsy after microbiological or histopathological examinations. The most identified organism was microsporidia (n = 4,30.7%), followed by mycobacteria (n = 2,15.4%), gram-negative bacilli (n = 2,15.4%), acid-fast bacilli (n = 1,7.6%), fungus (n = 2,15.4%), gram-positive cocci (n = 1,7.6%), and mixed bacterial infection (n = 1,7.6%). CONCLUSION: Corneal biopsy should be considered a diagnostic modality for patients with deep-seated or unresponsive MK. It can improve the treatment for MK, ensuring targeted therapy.

Endogenous TSG-6 modulates corneal inflammation following chemical injury.

PURPOSE: Tumor necrosis factor (TNF)-stimulated gene-6 (TSG-6) is upregulated in various pathophysiological contexts, where it has a diverse repertoire of immunoregulatory functions. Herein, we investigated the expression and function of TSG-6 during corneal homeostasis and after injury. METHODS: Human corneas, eyeballs from BALB/c (TSG-6+/+), TSG-6+/- and TSG-6-/- mice, human immortalized corneal epithelial cells and murine corneal epithelial progenitor cells were prepared for immunostaining and real time PCR analysis of endogenous expression of TSG-6. Mice were subjected to unilateral corneal debridement or alkali burn (AB) injuries and wound healing assessed over time using fluorescein stain, in vivo confocal microscopy and histology. RESULTS: TSG-6 is endogenously expressed in the human and mouse cornea and established corneal epithelial cell lines and is upregulated after injury. A loss of TSG-6 has no structural and functional effect in the cornea during homeostasis. No differences were noted in the rate of corneal epithelial wound closure between BALB/c, TSG-6+/- and TSG-6-/- mice. TSG-6-/- mice presented decreased inflammatory response within the first 24 h of injury and accelerated corneal wound healing following AB when compared to control mice. CONCLUSION: TSG-6 is endogenously expressed in the cornea and upregulated after injury where it propagates the inflammatory response following chemical injury.

Use of Corneal Topography in Pediatric Ophthalmology.

AIM: To introduce the topic of pediatric keratoconus, highlighting the importance of routine corneal topography and tomography in children and adolescents from predisposed groups. To attempt to ensure the early detection of keratoconus and its subclinical form, enabling early treatment, which brings better expected postoperative results.  Material and methods: Using the corneal tomograph Pentacam AXL we examined children and adolescents with astigmatism equal or greater than  2 diopters (in at least one eye) and patients with at least one risk factor such as eye rubbing in the case of allergic pathologies, positive family history of keratoconus or certain forms of retinal dystrophy. In total, we included 231 eyes (116 patients), of which 54 were girls and 62 were boys. RESULTS: The Belin-Ambrósio deviation index parameter was evaluated, in which we classified a total of 41 eyes as subclinical keratoconus and 12 eyes as clinical keratoconus. Next, the corneal maps were evaluated individually, in which we included a total of 15 eyes as subclinical keratoconus and 6 eyes as clinical keratoconus. In our group, compared to the control group, subclinical and clinical keratoconus occurred most often in the group of patients with astigmatism and in the group of so-called "eye rubbers". After individual evaluation, keratoconus occurred more frequently in boys than in girls in our cohort. CONCLUSION: Most patients with keratoconus are diagnosed when there is a deterioration of visual acuity and changes on the anterior surface of  the cornea. Corneal topography and tomography allows us to monitor the initial changes on the posterior surface of the cornea, and helps us to detect the subclinical form of keratoconus and the possibility of its early treatment. Therefore, it is important to determine which groups are at risk and groups in which corneal topography and tomography should be performed routinely.

Pigmented pyogenic granuloma of the cornea and conjunctiva: a rare bilateral presentation.

Pyogenic granuloma, also known as lobular capillary hemangioma, is a benign vascular lesion that primarily affects the skin and mucous membranes. It is not pyogenic; nor is it granulomatous. It typically arises in response to local trauma or surgery, irritation, hormonal changes, or chronic inflammation, and it sometimes occurs spontaneously. The occurrence of pigmented pyogenic granuloma in the conjunctiva and cornea without any history of trauma or surgery is extremely rare, particularly in children. We report the clinical presentation, diagnostic evaluation, and successful management of bilateral biopsy-proven conjunctival and corneal pigmented isolated pyogenic granuloma in an 11-year-old girl. No signs of recurrence were seen at the 3-months follow-up.