Visualization of corneal vascularization in peripheral hypertrophic subepithelial corneal opacification with OCT angiography.

PURPOSE: The major goal of this study was to test the hypothesis that in patients with peripheral hypertrophic subepithelial corneal opacification (PHSCO), visualization of corneal vessels is better with optical coherence tomography angiography (OCTA) than with conventional slit lamp microphotography. METHODS: Patients with PHSCO were included in this prospective study. The corneal findings were photographed using a slit lamp camera (Haag Streit BM 900® ) and visualized with anterior-segment OCT (Optovue XR Avanti, Fremont, California, USA). Additionally, OCTA with the Angiovue Imaging™ System was performed in the area of PHSCO. RESULTS: Thirty-four eyes of 19 patients (26% male and 74% female) with PHSCO were included in this study. In 21 eyes, vascularization in the area of PHSCO was visualized with the Angiovue-OCT, whereas only 10 eyes presented vessels in slit lamp photographs. CONCLUSION: Optical coherence tomography angiography allows better visualization of corneal neovascularization than slit lamp photography in patients with PHSCO. Corneal opacifications were found predominantly nasally, which was reflected by a local enlargement of corneal thickness.

Intraepithelial corneal haemorrhage in a rigid contact lens wearer.

Intracorneal haemorrhage is a rare complication of modern contact lens wear. While a limited number of reports have described intracorneal haemorrhages (typically stromal) associated with the extended wear of soft contact lenses with limited oxygen permeability for the correction of aphakia, this case report documents the management and resolution of a significant intraepithelial corneal haemorrhage associated with long-term rigid contact lens wear for keratoconus and high myopia.

Potential role of corneal epithelial cell-derived exosomes in corneal wound healing and neovascularization.

Specific factors from the corneal epithelium underlying the stimulation of stromal fibrosis and myofibroblast formation in corneal wound healing have not been fully elucidated. Given that exosomes are known to transfer bioactive molecules among cells and play crucial roles in wound healing, angiogenesis, and cancer, we hypothesized that corneal epithelial cell-derived exosomes may gain access to the underlying stromal fibroblasts upon disruption of the epithelial basement membrane and that they induce signaling events essential for corneal wound healing. In the present study, exosome-like vesicles were observed between corneal epithelial cells and the stroma during wound healing after corneal epithelial debridement. These vesicles were also found in the stroma following anterior stromal keratectomy, in which surgical removal of the epithelium, basement membrane, and anterior stroma was performed. Exosomes secreted by mouse corneal epithelial cells were found to fuse to keratocytes in vitro and to induce myofibroblast transformation. In addition, epithelial cell-derived exosomes induced endothelial cell proliferation and ex vivo aortic ring sprouting. Our results indicate that epithelial cell-derived exosomes mediate communication between corneal epithelial cells and corneal keratocytes as well as vascular endothelial cells. These findings demonstrate that epithelial-derived exosomes may be involved in corneal wound healing and neovascularization, and thus, may serve as targets for potential therapeutic interventions.

MMP14 Regulates VEGFR3 Expression on Corneal Epithelial Cells.

Vascular endothelial growth factor receptor 3 (VEGFR3) regulates the growth and differentiation of blood and lymphatic vessels. To determine whether matrix metalloproteinase 14 (MMP14) modulates VEGFR3 expression in the corneal epithelium to influence the avascularity of the cornea, VEGFR3 expression was compared between wild-type and MMP14-deficient (MMP14 Δexon4) corneal epithelial cells. Western blot analysis showed that VEGFR3 protein expression was higher on MMP14 Δexon4 corneal epithelial cells than on wild-type cells, and quantitative RT-PCR analysis showed that VEGFR3 gene expression was highly induced in MMP14 Δexon4 corneal epithelial cells but not in wild-type corneal epithelial cells or wild-type and MMP14 Δexon4 corneal keratocytes. Unlike in epithelial cells, MMP14 Δexon4 keratocytes did not express relatively higher levels of VEGFR3 than wild-type keratocytes. Interestingly, in vitro proteolysis experiments showed that MMP14 does not cleave VEGFR3 in vitro as it does VEGFR1, indicating that other genes may be involved in the modulation of VEGFR3 expression by MMP14. Using proteomic analysis to identify candidate factors, we found that 39 nuclear proteins were differentially expressed between wildtype and MMP14 Δexon4 corneal epithelial cells. These findings suggest that MMP14 may regulate VEGFR3 expression at the transcriptional level on corneal epithelial cells but not on corneal keratocytes.

Factors Influencing Intraocular Pressure Changes after Laser In Situ Keratomileusis with Flaps Created by Femtosecond Laser or Mechanical Microkeratome.

The aim of this study is to describe factors that influence the measured intraocular pressure (IOP) change and to develop a predictive model after myopic laser in situ keratomileusis (LASIK) with a femtosecond (FS) laser or a microkeratome (MK). We retrospectively reviewed preoperative, intraoperative, and 12-month postoperative medical records in 2485 eyes of 1309 patients who underwent LASIK with an FS laser or an MK for myopia and myopic astigmatism. Data were extracted, such as preoperative age, sex, IOP, manifest spherical equivalent (MSE), central corneal keratometry (CCK), central corneal thickness (CCT), and intended flap thickness and postoperative IOP (postIOP) at 1, 6 and 12 months. Linear mixed model (LMM) and multivariate linear regression (MLR) method were used for data analysis. In both models, the preoperative CCT and ablation depth had significant effects on predicting IOP changes in the FS and MK groups. The intended flap thickness was a significant predictor only in the FS laser group (P < .0001 in both models). In the FS group, LMM and MLR could respectively explain 47.00% and 18.91% of the variation of postoperative IOP underestimation (R2 = 0.47 and R(2) = 0.1891). In the MK group, LMM and MLR could explain 37.79% and 19.13% of the variation of IOP underestimation (R(2) = 0.3779 and 0.1913 respectively). The best-fit model for prediction of IOP changes was the LMM in LASIK with an FS laser.

A Comparative Study of the Therapeutic Potential of Mesenchymal Stem Cells and Limbal Epithelial Stem Cells for Ocular Surface Reconstruction.

UNLABELLED: Stem cell-based therapy has become an attractive and promising approach for the treatment of severe injuries or thus-far incurable diseases. However, the use of stem cells is often limited by a shortage of available tissue-specific stem cells; therefore, other sources of stem cells are being investigated and tested. In this respect, mesenchymal stromal/stem cells (MSCs) have proven to be a promising stem cell type. In the present study, we prepared MSCs from bone marrow (BM-MSCs) or adipose tissue (Ad-MSCs) as well as limbal epithelial stem cells (LSCs), and their growth, differentiation, and secretory properties were compared. The cells were grown on nanofiber scaffolds and transferred onto the alkali-injured eye in a rabbit model, and their therapeutic potential was characterized. We found that BM-MSCs and tissue-specific LSCs had similar therapeutic effects. Clinical characterization of the healing process, as well as the evaluation of corneal thickness, re-epithelialization, neovascularization, and the suppression of a local inflammatory reaction, were comparable in the BM-MSC- and LSC-treated eyes, but results were significantly better than in injured, untreated eyes or in eyes treated with a nanofiber scaffold alone or with a nanofiber scaffold seeded with Ad-MSCs. Taken together, the results show that BM-MSCs' therapeutic effect on healing of injured corneal surface is comparable to that of tissue-specific LSCs. We suggest that BM-MSCs can be used for ocular surface regeneration in cases when autologous LSCs are absent or difficult to obtain. SIGNIFICANCE: Damage of ocular surface represents one of the most common causes of impaired vision or even blindness. Cell therapy, based on transplantation of stem cells, is an optimal treatment. However, if limbal stem cells (LSCs) are not available, other sources of stem cells are tested. Mesenchymal stem cells (MSCs) are a convenient type of cell for stem cell therapy. The therapeutic potential of LSCs and MSCs was compared in an experimental model of corneal injury, and healing was observed following chemical injury. MSCs and tissue-specific LSCs had similar therapeutic effects. The results suggest that bone marrow-derived MSCs can be used for ocular surface regeneration in cases when autologous LSCs are absent or difficult to obtain.

Different expression of angiogenesis-related factors between human cultivated corneal and oral epithelial sheets.

We developed a cultivated oral mucosal epithelial sheet (COE) transplantation system to address severe human ocular surface disorders. Unlike the cultivated corneal epithelial sheet (CCE), the COE induces mild superficial peripheral neovascularization although central clarity is maintained. To evaluate the characteristic differences between CCE and COE regarding to angiogenesis, we examined the expression of angiogenesis-related factors in CCE and COE. Using samples of CCE and COE, we immunohistochemically determined protein expression of the angiogenesis related factors: Thrombospondin-1 (TSP-1), pigment epithelium derived factor (PEDF), endostatin, angiostatin, vascular endothelial growth factor (VEGF), Fms-like tyrosine kinase 1 (Flt-1), kinase insert domain receptor (KDR), and basic fibroblast growth factor (bFGF). We used Western blot analysis to confirm the factors that were immunohistochemically different in CCE and COE. The immunohistochemical staining intensity of TSP-1 was higher in CCE than COE and by Western blot analysis the expression of TSP-1 was significantly higher in CCE than COE (P<0.05). PEDF and endostatin stained moderately stronger in CCE than COE. Immunohistochemically there was no obvious difference between CCE and COE with respect to angiostatin, VEGF, Flt-1, KDR, and bFGF. In comparison with CCE, COE showed decreased expression of anti-angiogenic factors particularly TSP-1. This different expression may relate to the superficial peripheral neovascularization encountered after COE transplantation.

Topical cyclosporin stimulates neovascularization in resolving sterile rheumatoid central corneal ulcers.

OBJECTIVE: To report the successful use of topical cyclosporin for treatment of central sterile corneal ulcers associated with rheumatoid disease. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS/INTERVENTION: Five patients (7 eyes) with collagen vascular disorders presented with central, sterile corneal ulcers. An extensive medical evaluation did not reveal active underlying rheumatoid disease in any patient. Inadequate clinical response with use of topical steroids and lubricants led to corneal perforations requiring multiple tectonic procedures. Systemic immunosuppressive therapy either could not be initiated owing to a systemic contraindication or was discontinued owing to intolerance and side effects. The patients were ultimately treated with topical cyclosporin. RESULTS: Six of the 7 eyes responded favorably. An intense limbal vascularization began within 48 hours of treatment. The neovascularization progressed centrally with the simultaneous arresting of epithelial and stromal ulceration. Over a 2-week period, re-epithelization occurred with vascularization proceeding throughout the cornea. After several months, the corneal vessels attenuated, and all signs of inflammation subsided. Intrastromal bleeding with corneal blood staining occurred in 1 patient; this resolved over several months. No recurrences of corneal ulceration occurred in a mean follow-up period of 28 months (range, 7 to 60 months). None of the 5 patients have had a reactivation of their rheumatoid disease in the follow-up period. CONCLUSION: The clinical response in these patients contrasts with previous animal studies demonstrating an anti-angiogenic property of cyclosporin. We report that an immediate intense neovascularization is the first sign of a favorable clinical response. Treatment with topical cyclosporin alone may be considered in patients with sterile corneal ulcers associated with rheumatoid disease in the absence of systemic activation.