Available Therapeutic Options for Corneal Neovascularization: A Review.

Corneal neovascularization can impair vision and result in a poor quality of life. The pathogenesis involves a complex interplay of angiogenic factors, notably vascular endothelial growth factor (VEGF). This review provides a comprehensive overview of potential therapies for corneal neovascularization, covering tissue inhibitors of metalloproteinases (TIMPs), transforming growth factor beta (TGF-ß) inhibitors, interleukin-1L receptor antagonist (IL-1 Ra), nitric oxide synthase (NOS) isoforms, galectin-3 inhibitors, retinal pigment epithelium-derived factor (PEDF), platelet-derived growth factor (PDGF) receptor inhibitors, and surgical treatments. Conventional treatments include anti-VEGF therapy and laser interventions, while emerging therapies such as immunosuppressive drugs (cyclosporine and rapamycin) have been explored. Losartan and decorin are potential antifibrotic agents that mitigate TGF-ß-induced fibrosis. Ocular nanosystems are innovative drug-delivery platforms that facilitate the targeted release of therapeutic agents. Gene therapies, such as small interfering RNA and antisense oligonucleotides, are promising approaches for selectively inhibiting angiogenesis-related gene expression. Aganirsen is efficacious in reducing the corneal neovascularization area without significant adverse effects. These multifaceted approaches underscore the corneal neovascularization management complexity and highlight ideas for enhancing therapeutic outcomes. Furthermore, the importance of combination therapies and the need for further research to develop specific inhibitors while considering their therapeutic efficacy and potential adverse effects are discussed.

Current trends in the management of corneal neovascularization.

PURPOSE OF REVIEW: The aim of this study was to highlight recent developments in the medical and surgical management of corneal neovascularization (NV). RECENT FINDINGS: Improved understanding and diagnostic criteria among clinicians have led to advancements in the characterization of corneal NV and objective assessment of treatment response through ancillary imaging devices. Developments in corneal NV treatments, such as antivascular endothelial growth factor, fine needle diathermy, and photodynamic therapy, have improved treatment success rates and visual outcomes. More recent surgical treatment advancements include corneal cross-linking, endothelial keratoplasty, and mitomycin intravascular chemoembolization. Finally, a greater appreciation of the molecular pathogenesis and angiogenic factors involved in corneal NV has identified numerous potential targeted therapies in the future. SUMMARY: The management of corneal NV has evolved to include several standalone and combination medical and surgical options. Additionally, improvements in quantifying corneal NV and understanding its molecular basis have contributed to new management strategies with improved outcomes.

Management of corneal neovascularization: Current and emerging therapeutic approaches.

Corneal neovascularization (CoNV) is a sight-threatening condition affecting an estimated 1.4 million people per year, and the incidence is expected to rise. It is a complication of corneal pathological diseases such as infective keratitis, chemical burn, corneal limbal stem cell deficiency, mechanical trauma, and immunological rejection after keratoplasties. CoNV occurs due to a disequilibrium in proangiogenic and antiangiogenic mediators, involving a complex system of molecular interactions. Treatment of CoNV is challenging, and no therapy thus far has been curative. Anti-inflammatory agents such as corticosteroids are the mainstay of treatment due to their accessibility and well-studied safety profile. However, they have limited effectiveness and are unable to regress more mature neovascularization. With the advent of advanced imaging modalities and an expanding understanding of its pathogenesis, contemporary treatments targeting a wide array of molecular mechanisms and surgical options are gaining traction. This review aims to summarize evidence regarding conventional and emerging therapeutic options for CoNV.

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.

[Methods of diagnosis and treatment of corneal neovascularization]. / Metody diagnostiki i lecheniya neovaskulyarizatsii rogovitsy.

Corneal neovascularization is one of the most common causes of decreased visual acuity and disability for vision loss, increase in the risk of corneal graft rejection, and appearance of opacifications on the cornea. This article reviews literature on etiological factors of the development of corneal neovascularization, as well as modern methods of diagnosis, conservative and surgical treatment of this pathology.

A Mouse Model for Corneal Neovascularization by Alkali Burn.

Corneal neovascularization (CoNV), a pathological form of angiogenesis, involves the growth of blood and lymph vessels into the avascular cornea from the limbus and adversely affects transparency and vision. Alkali burn is one of the most common forms of ocular trauma that leads to CoNV. In this protocol, CoNV is experimentally induced using sodium hydroxide solution in a controlled manner to ensure reproducibility. The alkali burn model is useful for understanding the pathology of CoNV and can be extended to study angiogenesis in general because of the avascularity, transparency, and accessibility of the cornea. In this work, CoNV was analyzed by direct examination under a dissecting microscope and by immunostaining flat-mount corneas using anti-CD31 mAb. Lymphangiogenesis was detected on flat-mount corneas by immunostaining using anti-LYVE-1 mAb. Corneal edema was visualized and quantified using optical coherence tomography (OCT). In summary, this model will help to advance existing neovascularization assays and discover new treatment strategies for pathologic ocular and extraocular angiogenesis.

Long-Term Benefits of Tear Exchangeable Limbal-Rigid Contact Lens Wear Therapy in Stevens-Johnson Syndrome Cases.

OBJECTIVES: To evaluate the long-term benefits of tear-exchangeable, limbal-rigid contact lens (CL) wear therapy in patients with Stevens-Johnson syndrome (SJS)-associated ocular sequelae. METHODS: This retrospective study evaluated 50 eyes of 41 SJS patients (15 men and 26 women) who underwent limbal-rigid CL wear therapy for more than 2 years post fitting. Ocular sequelae (i.e., conjunctival hyperemia, corneal neovascularization, and upper tarsus scarring) before fitting and at 3 months, 6 months, 12 months, and annually after initiating CL wear therapy were evaluated and then graded on a severity score (range: 0-3, maximum score: 3). Moreover, visual acuity (VA) at immediately post initiating CL wear therapy was evaluated. RESULTS: The mean follow-up period was 4.3±1.1 years. Compared with before fitting, the mean conjunctival hyperemia score improved from 1.14 to 0.86 at 3 months of CL wear therapy ( P <0.01) and was maintained thereafter; the mean corneal neovascularization score improved from 2.10 to 1.98 at 3 months of CL wear therapy, with no deterioration of the score observed in all cases at the final follow-up examination, and mean VA (log of minimum angle of resolution) improved from 1.60 to 1.04 at immediately post initiating CL wear therapy ( P <0.01). CONCLUSIONS: Limbal-rigid CL wear therapy can provide long-term ocular surface stabilization and improved VA in SJS patients.

Fine-needle diathermy for corneal vascularisation.

Background: Corneal angiogenesis occurs as a sequel to an insult and it brings with it cells that mediate immunity as well as repair and aids in flushing toxins out. These vessels are formed in haste and leak lipid and cells, ultimately resulting in loss of transparency, lipid keratopathy and immunogenicity. So, they may need treatment prior to an optical keratoplasty. Purpose: To demonstrate the procedure of Fine Needle Diathermy (FND) to treat corneal neovascularization, its indications and contraindications. Synopsis: FND uses coagulating current from a monopolar cautery unit to occlude the afferent and efferent blood vessels. FND works best at the stage of mature vessel formation. The needle is placed across a tuft of vessels or parallel to a single large vessel, being mindful of the depth and direction. FND is avoided in necrotic tissue where the blood vessel is needed for healing process. Occlusion of the vessel in these situations may result in tissue melt. Highlights: Corneal neovascularization follows the stages of latent phase, active neovascularization, mature vessel formation and then regression. The treatment modality depends on the stage of angiogenesis. FND works best for neovascularization due to infectious keratitis. Keratoplasty is best performed 3 to 4 months later when regression of corneal vascularization occurs. Video Link: https://youtu.be/2RK6d_a2Gdc.

Therapeutic potential of topical administration of siRNAs against HIF-1α for corneal neovascularization.

Given the implications of the problem of neovascularization on ocular health, as well as the growth in the number of cases, the purpose of the present study has been testing the efficacy of siRNAs (small interfering RNA) designed to silence Hypoxia Inducible Factor -1α (HIF-1α) and to demonstrate that their use stops neovascularization in a model of corneal burn. Corneal wounds in the limbic zone were made in the eyes of New Zealand white rabbits. Topical applications of siRNAs were done the next day to the wound for four consecutive days and eyes were examined with a slit lamp. Evaluation of neovascularization progress was done by analyzing images by ImageJTM and to determine the neovascular area in Matlab ® was used. At the same time, a rabbit corneal cell line was used for in vitro study of hypoxia exposure and Western blot analysis of the cell's extracts were done. Under normal cell culture oxygenation, the expression of HIF-1α was lower than that observed under hypoxic conditions. After 2 h of hypoxia, there was a significant increase in the HIF-1α expression, effect that was maintained up to 6 h. The increased in HIF-1α was mimicked by a cell permeable prolyl-4-hydroxylase inhibitor. Cobalt chloride showed no capacity to increase HIF-1α in vitro. The effect of three different siRNA on HIF-1α was tested after 4 h of hypoxia. siRNA#1 was able to silence 80% of HIF-1α expression, siRNA#2 and siRNA#3 reduce the expression in 45% and 40% respectively. In addition, the three siRNA were tested in a corneal model of neovascularization. scrambledsiRNA#2 was the most effective inhibitor of blood vessel production, followed by siRNA#3 and siRNA#1. Compared to the scrambled siRNA (100% of blood vessel generation), siRNA#2 blocked the presence of blood vessels by 83 ± 2%, siRNA#3 inhibited 45 ± 7% and siRNA#1 only inhibited 18 ± 5%. The necessary time to observe the 50% of effect showed values of NV50 of 10.2 ± 2.4 days for the scrambled siRNA, 9.1 ± 1.4 for siRNA#1, 6.5 ± 1.85 for siRNA#2 and 4.8 ± 1.8 days for siRNA#3. In conclusion, the topical application of siRNA towards HIF-1α seems to be an effective and reliable method to stop neovascularization.

Initial outcomes of mitomycin intravascular chemoembolization (MICE) for corneal neovascularization.

PURPOSE: To report on the preliminary outcomes of mitomycin C (MMC) intravascular chemoembolization (MICE) for corneal neovascularization (NV). METHODS: This is a retrospective case series of three consecutive eyes that underwent MICE for progressive corneal NV with sight threatening lipid keratopathy. A 1.0 cc syringe was partially filled with MMC (0.4 mg/mL) and attached to a 33-gauge needle used to cannulate the vessels. The MMC (0.01-0.05 ml) was injected with enough retrograde hydrostatic force to fill efferent and afferent vessels. Follow-up ranged from 4 months to 1 year. RESULTS: Three eyes of three patients aged 59, 73 and 33 years were included. There were no intraoperative or postoperative complications associated with the MICE procedure. Patient 1 presented with progressive corneal NV and lipid keratopathy secondary to herpes zoster ophthalmicus (HZO) and a best-corrected spectacle visual acuity (BSCVA) of 20/100 Snellen. At one-year post-MICE, there was no recurrence (BSCVA was 20/20 Snellen). Patient 2 presented with idiopathic lipid keratopathy (BSCVA 20/50 Snellen). At four months post-MICE, there were no signs of recurrence (BSCVA 20/20 Snellen). Patient 3 presented with corneal NV and lipid keratopathy secondary to HZO (BSCVA 20/30 Snellen). At four months following two MICE treatments, resolution of the lipid keratopathy was noted (BSCVA 20/20 Snellen). CONCLUSIONS: Preliminary findings suggest that MICE may be an additional modality for treating progressive corneal NV with lipid keratopathy. Larger comparative studies with longer follow-up are warranted.

miR-340-5p mediates the therapeutic effect of mesenchymal stem cells on corneal neovascularization.

BACKGROUND: Our previous study revealed that mesenchymal stem cells (MSCs) inhibited angiogenesis via miRNA-mediated repression of prospero homeobox 1 (PROX1). This study aimed to verify whether miR-340-5p participates in the therapeutic effect of MSCs on corneal neovascularization (CNV) via repressing PROX1 and epithelial membrane protein 2 (EMP2). MATERIALS AND METHODS: The rat CNV model was established by corneal alkali burn. The binding relationship between miR-340-5p and 3'-untranslational regions (3'UTRs) of EMP2 and PROX1 was confirmed using dual-luciferase reporter assay. After culturing corneal epithelial cells (CECs) using MSC supernatants, the vascular endothelial growth factor (VEGF) level in CEC supernatants and the CEC viability were detected. The role of miR-340-5p in the therapeutic effect of MSC on CNV was determined via lentivirus-mediated miR-340-5p intervention in vivo. RESULTS: The expression of miR-340-5p was reduced and EMP2 and PROX1 were increased in CNV corneal tissues. The lentivirus-mediated overexpression of miR-340-5p inhibited the expressions of EMP2 and PROX1. The dual-luciferase reporter assay confirmed that miR-340-5p could bind with the 3'UTRs of EMP2 and PROX1. miR-340-5p was enriched in MSC supernatants and the culture of CECs using MSC supernatants increased the miR-340-5p expression in CECs. After being cultured in miR-340-5p-knocking down MSC supernatants, the expressions of EMP2 and PROX1 were increased, and the VEGF level and CEC viability were restored. The in vivo experiments also indicated that the therapeutic effect of MSCs was mediated by miR-340-5p. CONCLUSIONS: miR-340-5p mediates the therapeutic effect of MSCs on CNV via binding and repressing the expressions of EMP2 and PROX1.

Cutting Edge: Novel Treatment Options Targeting Corneal Neovascularization to Improve High-Risk Corneal Graft Survival.

PURPOSE: Corneal neovascularization is an important risk factor for graft rejection after keratoplasty, although its role in posterior lamellar keratoplasty is not yet well defined. The aim of this work was to describe clinically available approaches that target corneal neovascularization preoperatively to improve graft survival after subsequent penetrating keratoplasty (PK) and to present findings on Descemet membrane endothelial keratoplasty (DMEK) in eyes with neovascularization. METHODS: Recent work on the use of anti-vascular endothelial growth factor agents, fine needle diathermy (FND), and corneal collagen crosslinking (CXL) to regress corneal neovascularization before PK is summarized. Furthermore, studies that have investigated the outcome of DMEK in vascularized eyes are presented. RESULTS: Pretreatment of recipient corneas with FND combined with anti-vascular endothelial growth factor agents is an effective method to reduce long-standing corneal neovascularization and results in relatively low rejection rates after subsequent high-risk PK. Peripheral CXL also seems to be a potent method to regress corneal neovascularization, although data on the impact of pretransplant CXL on long-term graft survival are not yet available. There are only limited data on graft rejection rates after DMEK in vascularized eyes, but initial studies indicate that DMEK seems to be a viable therapeutic option when no stromal scars are present. Furthermore, preexisting stromal neovascularization seems to regress after high-risk DMEK. CONCLUSIONS: Several angioregressive strategies to treat corneal neovascularization before PK have entered the clinic with promising initial results, which warrants larger trials with longer follow-up. Studies will also have to define the precise role of preexisting corneal neovascularization in high-risk DMEK.

Photo-Mediated Ultrasound Therapy for the Treatment of Corneal Neovascularization in Rabbit Eyes.

Purpose: Corneal neovascularization (CNV) is the invasion of new blood vessels into the avascular cornea, leading to reduced corneal transparency and visual acuity, impaired vision, and even blindness. Current treatment options for CNV are limited. We developed a novel treatment method, termed photo-mediated ultrasound therapy (PUT), that combines laser and ultrasound, and we tested its feasibility for treating CNV in a rabbit model. Methods: A suture-induced CNV model was established in New Zealand White rabbits, which were randomly divided into two groups: PUT and control. For the PUT group, the applied light fluence at the corneal surface was estimated to be 27 mJ/cm2 at 1064-nm wavelength with a pulse duration of 5 ns, and the ultrasound pressure applied on the cornea was 0.43 MPa at 0.5 MHz. The control group received no treatment. Red-free photography and fluorescein angiography were utilized to evaluate the efficiency of PUT. Safety was evaluated by histology and immunohistochemistry. For comparison with the PUT safety results, conventional laser photocoagulation (LP) treatment was performed with standard clinical parameters: 532-nm continuous-wave (CW) laser with 0.1-second pulse duration, 450-mW power, and 75-µm spot size. Results: In the PUT group, only 1.8% ± 0.8% of the CNV remained 30 days after treatment. In contrast, 71.4% ± 7.2% of the CNV remained in the control group after 30 days. Safety evaluations showed that PUT did not cause any damage to the surrounding tissue. Conclusions: These results demonstrate that PUT is capable of removing CNV safely and effectively in this rabbit model. Translational Relevance: PUT can remove CNV safely and effectively.

G9a Suppression Alleviates Corneal Neovascularization through Blocking Nox4-Mediated Oxidative Stress.

BACKGROUND: G9a, a well-known methyltransferase, plays a vital role in biological processes. However, its role in corneal neovascularization (CoNV) remains unclear. Methods. In vitro and in vivo models were assessed in hypoxia-stimulated angiogenesis and in a mouse model of alkali burn-induced CoNV. Human umbilical vein endothelial cells (HUVECs) were cultured under hypoxic conditions and different reoxygenation times to identify the molecular mechanisms involved in this process. RESULTS: In this study, we found that G9a was positively related to corneal alkali burn-induced injury. Inhibition of G9a with BIX 01294 (BIX) alleviated corneal injury, including oxidative stress and neovascularization in vivo models were assessed in hypoxia-stimulated angiogenesis and in a mouse model of alkali burn-induced CoNV. Human umbilical vein endothelial cells (HUVECs) were cultured under hypoxic conditions and different reoxygenation times to identify the molecular mechanisms involved in this process.

Supplemental Anti Vegf A-Therapy Prevents Rebound Neovascularisation After Fine Needle Diathermy Treatment to Regress Pathological Corneal (LYMPH)Angiogenesis.

Fine needle diathermy (FND) is an effective method to destroy and regress pathologic corneal blood and lymphatic vessels. However, it is unknown whether FND itself causes a rebound corneal neovascularisation and whether that can be prevented by VEGF blockade. In female BALB/c mice, the suture-induced inflammatory corneal neovascularisation model was used to induce hem- and lymphangiogenesis. Thereafter, prevascularized mice were divided into 2 groups: the combination therapy group received FND cauterization and subsequent VEGF TrapR1R2 eye drops three times per day whereas the monotherapy group was treated only with FND. Three, 7 and 14 days after the treatment, corneas were collected and stained with FITC-conjugated CD31 and LYVE-1 followed by Cy3-conjugated secondary antibody to quantify corneal blood and lymphatic vessels. Relative mRNA expression of VEGF in the cornea was quantified by using qPCR. FND cauterization as monotherapy significantly obliterated (lymph)angiogenesis at early time points; however, this treatment led to secondary corneal hem- and lymphangiogenesis associated with significant upregulation of pro(lymph)angiogenic VEGF-A, VEGF-C, VEGF-D and infiltration of macrophages. Combining FND cauterization with VEGF TrapR1R2 treatment prevented the undesired effect of the FND procedure alone and significantly better regressed corneal blood and lymphatic vessels at 1 week after the treatment compared to monotherapy and control group (p < 0.01).

Subconjunctival bevacizumab and argon laser photocoagulation for preexisting neovascularization following deep lamellar anterior keratoplasty.

We report a rare case of deep anterior lamellar keratoplasty (DALK) neovascularization managed with combination of subconjunctival bevacizumab and argon laser photocoagulation. A 24 year old male underwent Deep anterior lamellar keratoplasty for corneal stromal opacity following presumed viral keratitis. Deep corneal neovascularization was observed postoperatively which was successfully managed using a combination of subconjunctival bevacizumab and argon laser photocoagulation within one week of DALK. The neovascularization resolved by 3 months and at 2 years follow up, patient maintained good visual acuity of 6/12 Snellen's without recurrence of vascularization. A combination of bevacizumab and argon laser may be an effective approach to manage neovascularisation in the immediate postoperative phase (Post DALK) and improve graft survival.

Corneal neovascularization: updates on pathophysiology, investigations & management.

Objective. Corneal neovascularization is a sight-threatening condition affecting more than 1.4 million people per year. Left untreated, it can lead to tissue scarring, oedema, lipid deposition, and persistent inflammation that may significantly affect visual prognosis and quality of life. The aim was to review the recent evidence relating to the pathophysiology, investigations and management of corneal neovascularization. Methods. Literature review of prospective and retrospective studies, clinical trials and animal models relating to the pathophysiology, investigation and management of corneal neovascularization. Results. Corneal neovascularization is characterized by the invasion of new blood vessels into the cornea caused by an imbalance between angiogenic and antiangiogenic factors that preserve corneal transparency as a result of various ocular insults and hypoxic injuries. Risk factors that have been implicated in the pathogenesis of the disease include contact lens wear, ocular surface disease, trauma, previous surgery and herpes. The results highlighted the current and future management modalities of corneal neovascularization, which includes corneal transplantation, laser - phototherapy, injections and topical treatment. Conclusion. The future of corneal neovascularization is promising and this paper discusses the upcoming revolution in local gene therapy. Abbreviations. HSK = herpes stromal keratitis, VEGF = vascular endothelial growth factor, VEGFR-1 = VEGF Receptor-1, FGF = Fibroblast growth factor, PDGF = Platelet-derived growth factor, IL-6 = interleukin-6, IL-7 = interleukin-7, IL-8 = interleukin-8, IRS-1 = insulin receptor substrate-1.

MicroRNAs in the cornea: Role and implications for treatment of corneal neovascularization.

With no safe and efficient approved therapy available for treating corneal neovascularization, the search for alternative and effective treatments is of great importance. Since the discovery of miRNAs as key regulators of gene expression, knowledge of their function in the eye has expanded continuously, facilitated by high throughput genomic tools such as microarrays and RNA sequencing. Recently, reports have emerged implicating miRNAs in pathological and developmental angiogenesis. This has led to the idea of targeting these regulatory molecules as a therapeutic approach for treating corneal neovascularization. With the growing volume of data generated from high throughput tools applied to study corneal neovascularization, we provide here a focused review of the known miRNAs related to corneal neovascularization, while presenting new experimental data and insights for future research and therapy development.