Subconjunctival bevacizumab injection for corneal neovascularization

Localization of fluorescent gold nanoparticles throughout the eye after topical administration

The human eye is a highly intricate sensory organ. When a condition requiring treatment occurs, eyedrops, which represent 90% of all ophthalmic treatments, are most frequently used. However, eyedrops are associated with low bioavailability, with less than 0.02% of therapeutic molecules reaching the anterior chamber. Thus, new delivery systems are required to ensure sufficient drug concentration over time at the target site. Gold nanoparticles are a promising avenue for drug delivery; however, they can be difficult to track in biological systems. Fluorescent gold nanoparticles, which have the same ultrastability and biocompatibility as their nonfluorescent counterpart, could act as an effective imaging tool to study their localization throughout the eye after administration. Thus, this study (1) synthesized and characterized fluorescent gold nanoparticles, (2) validated similar properties between nonfluorescent and fluorescent gold nanoparticles, and (3) determined their localization in the eye after topical application on ex vivo rabbit eyes. The fluorescent gold nanoparticles were synthesized, characterized, and identified in the cornea, iris, lens, and posterior segment of rabbit eyeballs, demonstrating tremendous potential for future drug delivery research.

Recombinant Thrombomodulin Domain 1 Modulates Macrophage Polarization and Enhances Healing in Corneal Alkali Burns

Purpose

Corneal alkali burns are severe ocular injuries characterized by intense inflammation, tissue damage, and vision impairment, with current treatments often insufficient in restoring corneal function and clarity. This study aimed to evaluate the therapeutic effects of recombinant thrombomodulin domain 1 (rTMD1) in the treatment of corneal alkali burns, focusing on its impact on inflammation, tissue repair, fibrosis, and neovascularization.

Methods

A murine model of corneal alkali burn was utilized to investigate the therapeutic potential of rTMD1. The effects of rTMD1 on macrophage polarization, inflammatory response, tissue repair, fibrosis, and neovascularization were assessed through histological analysis, immunohistochemistry, and molecular studies targeting key signaling pathways such as ERK/HIF-1α and vascular endothelial growth factor (VEGF) expression.

Results

Administration of rTMD1 significantly modulated macrophage polarization, promoting a transition from the pro-inflammatory M1 phenotype to the reparative M2 phenotype via inhibition of the ERK/HIF-1α pathway. This shift resulted in reduced inflammation, enhanced tissue repair, and controlled fibrosis. Furthermore, rTMD1 inhibited neovascularization by downregulating VEGF expression, aiding in the preservation of corneal clarity.

Conclusions

rTMD1 demonstrates substantial therapeutic potential in treating corneal alkali burns by reducing inflammation, promoting tissue repair, controlling fibrosis, and inhibiting neovascularization. These findings support the further development of rTMD1 as a promising treatment for corneal burns and possibly other inflammatory ocular conditions.

Viral Keratitis, Surgical Intervention in Viral Keratitis, Challenges in Diagnosis and Treatment of Viral Keratitis, HSV, HZV

Viral keratitis is a significant cause of ocular morbidity and visual impairment worldwide. In recent years, there has been a growing understanding of the pathogenesis, clinical manifestations, and diagnostic modalities for viral keratitis. The most common viral pathogens associated with this condition are adenovirus, herpes simplex (HSV), and varicella-zoster virus (VZV). However, emerging viruses such as cytomegalovirus (CMV), Epstein-Barr virus (EBV), and Vaccinia virus can also cause keratitis. Non-surgical interventions are the mainstay of treatment for viral keratitis. Antiviral agents such as Acyclovir, Ganciclovir, and trifluridine have effectively reduced viral replication and improved clinical outcomes. Additionally, adjunctive measures such as lubrication, corticosteroids, and immunomodulatory agents have alleviated symptoms by reducing inflammation and facilitating tissue repair. Despite these conservative approaches, some cases of viral keratitis may progress to severe forms, leading to corneal scarring, thinning, or perforation. In such instances, surgical intervention becomes necessary to restore corneal integrity and visual function. This review article aims to provide an overview of the current perspectives and surgical interventions in managing viral keratitis. The choice of surgical technique depends on the extent and severity of corneal involvement. As highlighted in this article, on-going research and advancements in surgical interventions hold promise for further improving outcomes in patients with viral keratitis.

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.

[A randomized study of subconjonctival bevacizumab (Avastin®) injection for corneal neovascularization]

PURPOSE

The goal of this phase III, comparative, multicentric, randomized, double-blinded clinical trial was to investigate the superiority of subconjunctival bevacizumab injections versus placebo in the treatment of corneal neovascularization.

PATIENTS AND METHODS

We included 38 eyes (38 patients) with corneal neovascularization. Twenty patients received bevacizumab and 18 placebos. Patients received 3 monthly injections of either 5mg (0.2mL) bevacizumab or placebo. The main criteria of success was reduction of the surface area of corneal neovascularization after 3months (M3) versus baseline, as measured using semi-automatic analysis of color photographs.

RESULTS

The percentage of neovascularized corneal surface decreased by -8.6%±32.8 with bevacizumab, versus -2.6%±20.8 with placebo (p=0.5284). Four patients were determined to be responders (reduction of more than 30%), 3 in the bevacizumab group and 1 in the placebo group, all with neovascularization of less than 1year duration. When restricting the analysis to neovascularization of less than 1 year duration, the difference approached the threshold for significance (-31.8%±42.4 in the bevacizumab group and -0.9%±23.1 in the placebo group) (p=0.0637), as well as the number of responders (3/6 in the bevacizumab group versus 1/10 in the placebo group) (p=0.1181). No serious adverse event was reported.

CONCLUSION

This study shows the efficacy of subconjunctival bevacizumab injection in the reduction of neovascularized corneal surface area versus placebo, but only when the neovascularization has been present less than 1year. Nevertheless, the study did not attain the statistical power to pass the threshold of significance.

Regenerated Corneal Epithelium Expresses More βIII-Tubulin After Chemical Injuries Compared to Mechanical Injuries

Purpose

Defining the regenerative response following various types of corneal chemical and mechanical injuries is important for understanding the pathophysiology of the injury and evaluating the effectiveness of the therapies. This study characterizes corneal epithelial healing in a murine chemical and mechanical injury model.

Methods

Four groups of 10 mice each received complete corneolimbal injuries by AlgerBrush, AlgerBrush/thermal, NaOH (0.5 N), or ethanol. Slit-lamp and optical coherence tomography examinations were performed daily for 14 days. Corneal opacity (CO) and neovascularization (NV) were evaluated. The origin of the regenerated epithelium was illustrated by anti-cytokeratin 12 (K12) and anti-K13. The height of regenerated corneal epithelium and intraepithelial free nerve endings (FNEs) stained with anti-βIII-tubulin were measured. The amount of fibrosis was measured by anti-α-smooth muscle actin (α-SMA) monoclonal antibody in the different groups. Statistical analysis was performed by ANOVA and t-test.

Results

Corneal opacity and neovascularization were markedly higher in the NaOH and AlgerBrush/thermal groups. Molecular studies revealed the following: Regenerated corneal epithelium thickness was less than normal in all groups, the AlgerBrush group had the shortest height of the regenerated epithelium, βIII-tubulin was expressed in the entire height of corneal epithelium in all groups except in the AlgerBrush group, and K12 was replaced by K13 in all groups.

Conclusions

Corneal wound healing is more effective following chemical injuries in terms of epithelial thickness. Inflammation may play an important role in the outcome.

Translational Relevance

Inflammation following different injuries may be redirected to be more effective in corneal regeneration and clarity.

An injectable thermosensitive hydrogel for dual delivery of diclofenac and Avastin® to effectively suppress inflammatory corneal neovascularization

Corneal neovascularization (CNV) is a sequela of anterior segment inflammation, which could lead to vision impairment and even blindness. In the present study, the dual delivery of anti-inflammatory agent (i.e., diclofenac; DIC) and anti-VEGF antibody (i.e., Avastin®; Ava) by the thermosensitive hydrogel (Poly(dl-lactide)-poly(ethylene glycol)-poly(dl-lactide); PDLLA-PEG-PDLLA) is expected to effectively inhibit CNV via their synergistic effects. The optimal DIC micelles were formulated and then mixed with Ava and PDLLA-PEG-PDLLA aqueous solution to generate various DIC@Ava-loaded hydrogels. The co-encapsulation of DIC micelles and Ava did not influence the gelling behavior of the system, and the resulting DIC@Ava-loaded hydrogel provided sustained drug release of both DIC and Ava without compromising their pharmacological activity over 19 days. As indicated by in vitro cytotoxicity and in vivo ocular biocompatibility test, the proposed PDLLA-PEG-PDLLA hydrogel caused minimal cytotoxicity against all tested cell lines at a polymeric concentration ranging from 0.05 mg/mL to 0.8 mg/mL and demonstrated good ocular biocompatibility after a single subconjunctival injection. Using the rabbit CNV model, we documented the superior anti-angiogenic effects of the DIC@Ava-loaded hydrogel over Ava alone medication (treatment with Ava solution and Ava-loaded hydrogel) due to synergistic effects of anti-VEGF and anti-inflammatory action. Overall, the proposed DIC@Ava-loaded hydrogel might be a powerful strategy to reduce CNV.

Bevacizumab in High-Risk Corneal Transplantation: A Pilot Multicenter Prospective Randomized Control Trial

PURPOSE

To determine the efficacy of local (subconjunctival and topical) bevacizumab (Avastin) treatment in patients undergoing vascularized high-risk corneal transplantation.

DESIGN

Pilot, prospective, randomized, double-blind, placebo-controlled clinical trial conducted at 5 clinical centers in the United States, India, and Brazil.

PARTICIPANTS

Patients aged > 18 years undergoing high-risk penetrating keratoplasty, defined as corneal neovascularization (NV) in 1 or more quadrants ≥2 mm from the limbus or extension of corneal NV to the graft-host junction in a previously failed graft.

METHODS

Patients were randomized to receive subconjunctival bevacizumab (2.5 mg/0.1 ml) or placebo at the time of surgery, followed by topical bevacizumab (10 mg/ml) or topical placebo, administered 4 times per day for 4 weeks.

MAIN OUTCOME MEASURE

The 52-week endothelial immune rejection rate.

RESULTS

Ninety-two patients were randomized to receive bevacizumab (n = 48) or control (n = 44). The 52-week endothelial rejection rate was 10% in the bevacizumab group and 19% in the control group (P = 0.20). Post hoc, extended follow-up at the lead study site showed an endothelial rejection rate of 3% in the bevacizumab group and 38% in the control group (P = 0.003). Treatment with bevacizumab was found to have a hazard ratio of 0.15 (95% confidence interval, 0.03-0.65, P = 0.01) in a post hoc Cox regression analysis.

CONCLUSIONS

In patients undergoing vascularized high-risk corneal transplantation, there was no statistically significant difference in the rate of endothelial rejection at 1 year in the bevacizumab treatment group compared with the control group. This study may have been underpowered to detect a difference between treatment groups, and taken together, our data suggest that, in the current trial design, bevacizumab has a positive but not (yet) significant effect on endothelial rejection.

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.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10792-022-02240-6.

Subconjunctival Aflibercept for the Treatment of Formed Corneal Neovascularization

PURPOSE

To evaluate the effect of a single subconjunctival aflibercept injection on formed corneal neovascularization.

METHODS

A prospective clinical trial, conducted at a single tertiary medical center. Included were consecutive patients with corneal pathologies complicated by corneal neovascularization, who were candidates for anti-vascular endothelial growth factor treatment at the discretion of a cornea specialist. A single subconjunctival injection of 0.08 mL of Aflibercept (Eylea 25 mg/mL) was administered near the limbus in proximity to the areas of maximal pathological neovascularization. Follow-up visits were scheduled on days 7, 30, 60, and 90 following injection. Best-corrected visual acuity (BCVA), intraocular pressure, slitlamp examination, digital cornea photography, specular microscopy, and anterior-segment optical coherence tomography were documented at each visit. The images were graded by a masked observer for density, extent, and centricity of corneal vascularization.

RESULTS

Six eyes of six patients were analyzed. No clinically significant ocular or systemic adverse events were documented. No change was noted in extent, density, or centricity of corneal blood vessels at seven, 30, and 90 days after injection (P>0.1 for all time point comparisons, Friedman test). Best-corrected visual acuity fluctuated insignificantly in 5/6 patients during follow-up time, and objective but not subjective improvement of BCVA was noted in one patient with no concurrent change of neovascularization. The recruitment has therefore halted prematurely.

CONCLUSIONS

A single subconjunctival aflibercept injection seems to be well tolerated. However, it is ineffective for regressing formed corneal neovascularization.

Shear-Thinning Viscous Materials for Subconjunctival Injection of Microparticles

While drug-loaded microparticles (MPs) can serve as drug reservoirs for sustained drug release and therapeutic effects, needle clogging by MPs poses a challenge for ocular drug delivery via injection. Two polymers commonly used in ophthalmic procedures-hyaluronic acid (HA) and methylcellulose (MC)-have been tested for their applicability for ocular injections. HA and MC were physically blended with sunitinib malate (SUN)-loaded PLGA MPs for subconjunctival (SCT) injection into rat eyes. The HA and MC viscous solutions facilitated injection through fine-gauged needles due to their shear-thinning properties as shown by rheological characterizations. The diffusion barrier presented by HA and MC reduced burst drug release and extended overall release from MPs. The significant level of MP retention in the conjunctiva tissue post-operation confirmed the minimal leakage of MPs following injection. The safety of HA and MC for ocular applications was demonstrated histologically.

Anti-VEGF Treatment in Corneal Diseases

BACKGROUND

Corneal neovascularization (CN) is a clue feature of different ocular pathological conditions and can lead to corneal edema and opacification with subsequent vision loss. Vascular endothelial growth factor (VEGF), which plays a key role in new vessels formation, proliferation and migration, was found to be up-regulated in these conditions. Nowadays, it is possible to downregulate the angiogenic process by using anti-VEGF agents administered by different routes.

OBJECTIVE

To evaluate the efficacy, safety and possible future directions of anti-VEGF agents used for the treatment of CNV owing to different aetiologies.

METHODS

A computerized search of articles dealing with the topic of anti-VEGF therapy in CN was conducted in PubMed, Scopus and Medline electronic databases. The following key phrases were used: anti-VEGF agents, corneal neovascularization, bevacizumab, ranibizumab, vascular endothelial growth factor, angiogenesis.

RESULTS

The use of anti-VEGF therapy in the treatment of CN reduced pathological vessel density without causing significant side effects. Various administration routes such as topical, subconjunctival and intrastromal ones are available, and the choice depends on patient and disease characteristics. Much more effectiveness is achieved in case of early administration before mature and wellestablished vessels take place. A combined approach between various drugs including anti-VEGF agents should be adopted in those cases at higher risk of neovascularization recurrence such as chronic long-standing diseases where ischemic and inflammatory stimuli are not definitively reversed.

CONCLUSION

The efficacy and safety of anti-VEGF agents support their adoption into the daily clinical practice for the management of CN.

Comparison of Topical Pigment Epithelium-Derived Factor (PEDF) with Topical Bevacizumab for Accelerating the Regression of Corneal Neovascularization in an Experimental Model of Rabbit Corneal Angiogenesis

Purpose: To evaluate the anti-angiogenic effect of topical administration of Pigment epithelium-derived factor (PEDF) on the reduction of corneal neovascularization (NV) in comparison to topical Bevacizumab.Methods: 18 eyes of 18 New Zealand rabbits were enrolled. Corneal NV was induced by a 7-0 silk suture. After suture removal, rabbits were randomly divided into three groups. In every group, one eye randomly treated with topical bevacizumab or topical PEDF or saline for 14 days. The area and length of neovascularization were measured by Image J. Histological studies were done in three groups.Results: After 14 days, the mean decrease of corneal NV length was 1.84 ± 0.17 mm (P < .001) in PEDF group and 1.6 ± 0.07 mm (P < .001) in bevacizumab group which was significantly more than the saline group (P = .001 and P < .001, respectively). There was no significant difference between PEDF and bevacizumab group in the reduction of corneal NV length (P = .85). The mean decrease of corneal NV area was 4.94 ± 0.55 mm² (P < .001) in PEDF group and 4.23 ± 0.29 mm² in the bevacizumab group (P < .001). PEDF and bevacizumab significantly decreased corneal NV area in comparison to the saline group (p = .017, p = .001, respectively). The mean decrease of corneal NV area did not show a significant difference between PEDF and bevacizumab groups (P = .72).Conclusion: Topical PEDF might be an effective and safe treatment option as bevacizumab in a short-term use, indicating that it is as good as the standard. However, long-term effect is required to be investigated.

Microarray Analysis of circRNA Expression Pattern in Corneal Neovascularization

PURPOSE

To identify differentially expressed circular RNAs (circRNAs) in corneal neovascularization.

METHODS

We established an alkali burn-induced corneal neovascularization model and performed circRNA expression profiling to identify differentially expressed circRNAs between avascular corneas and vascularized corneas. Gene ontology enrichment and Kyoto Encyclopedia of Genes and Genomes analyses of the host genes of dysregulated circRNAs were performed to determine the related biological modules and pathological pathways. Real-time polymerase chain reactions were performed to detect the expression pattern of circRNAs in the clinical samples. In vitro experiments were performed to determine the role of circRNAs in vascular endothelial angiogenic effects.

RESULTS

Two hundred twenty-nine circRNAs were differentially expressed between avascular corneas and vascularized corneas. The host genes of dysregulated circRNAs were targeted to cell cycle (biologic process), cytoplasm (cellular component), and protein binding (molecular function). Rap1 signaling was identified as the most enriched signaling pathway. Clinical studies showed that the human ortholog of cZFP609 and cKifap3 was dysregulated in the vascularized human corneas. cKifap3 silencing facilitated vascular endothelial angiogenic effects by regulating endothelial cell proliferation, migration, and tube formation.

CONCLUSIONS

This study suggests that circRNAs are involved in the pathogenesis of corneal neovascularization. cZFP609 and cKifap3 may serve as promising targets for the treatment of corneal neovascularization.

Comparison of Subconjunctival Aflibercept and Betamethasone for the Treatment of Formed Corneal Neovascularization in a Rabbit Model

AIM

To compare the efficacy of aflibercept (Eylea®), a potent antivascular endothelial growth factor (VEGF) agent, with betamethasone (Celestone®) and placebo for the treatment of formed corneal neovascularization in a rabbit model.

METHODS

A central corneal chemical burn was created in the right eye of 24 New Zealand albino rabbits. Four weeks later, the rabbits were randomly divided into 4 equal groups for subconjunctival injection of aflibercept, betamethasone, aflibercept+ betamethasone, or saline (control). Digital photographs taken at weekly intervals were rated by 2 masked observers for extent, centricity, and density of corneal neovascularization according to a predefined scale. The percentage of corneal surface involved by neovascularization was quantified by image analysis software (Fiji-J). The change in corneal neovascularization from treatment administration (4 weeks after injury) to 4 weeks later (8 weeks after injury) was assessed. The rabbits were then euthanized, and their eyes were enucleated and processed for histopathological and immunofluorescence studies.

RESULTS

There was no significant difference in the change in corneal neovascularization after treatment among the 4 groups according to the digital images (p > 0.15) or histological evaluation with hematoxylin and eosin (p > 0.08). On immunofluorescence assay, a lower VEGF concentration was observed in all treatment groups compared to the control group.

CONCLUSIONS

In this rabbit model, corneal neovascularization induced by chemical burn failed to regress with treatment with aflibercept, betamethasone, or their combination.

Epithelial Membrane Protein-2 (EMP2) Antibody Blockade Reduces Corneal Neovascularization in an In Vivo Model

Purpose

Pathologic corneal neovascularization is a major cause of blindness worldwide, and treatment options are currently limited. VEGF is one of the critical mediators of corneal neovascularization but current anti-VEGF therapies have produced limited results in the cornea. Thus, additional therapeutic agents are needed to enhance the antiangiogenic arsenal. Our group previously demonstrated epithelial membrane protein-2 (EMP2) involvement in pathologic angiogenesis in multiple cancer models including breast cancer and glioblastoma. In this paper, we investigate the efficacy of anti-EMP2 immunotherapy in the prevention of corneal neovascularization.

Methods

An in vivo murine cornea alkali burn model was used to study pathologic neovascularization. A unilateral corneal burn was induced using NaOH, and subconjunctival injection of either anti-EMP2 antibody, control antibody, or sterile saline was performed after corneal burn. Neovascularization was clinically scored at 7 days postalkali burn, and eyes were enucleated for histologic analysis and immunostaining including VEGF, CD31, and CD34 expression.

Results

Anti-EMP2 antibody, compared to control antibody or vehicle, significantly reduced neovascularization as measured by clinical score and central cornea thickness, as well as by histologic reduction of neovascularization, decreased CD34 staining, and decreased CD31 staining. Incubation of corneal limbal cells in vitro with anti-EMP2 blocking antibody significantly decreased EMP2 expression, VEGF expression and secretion, and cell migration.

Conclusions

This work demonstrates the effectiveness of EMP2 as a novel target in pathologic corneal neovascularization in an animal model and supports additional investigation into EMP2 antibody blockade as a potential new therapeutic option.

Topical axitinib is a potent inhibitor of corneal neovascularization

BACKGROUND

This study evaluated the effects of topically applied axitinib, a tyrosine kinase inhibitor, in an experimental model of corneal neovascularization (CNV).

METHODS

A total of 48 New Zealand rabbits were used. CNV was induced by placing five silk sutures in the upper cornea of one eye per rabbit. Rabbits were randomized into four groups (12 rabbits each): 0.9% saline (control group), 0.02 mg/mL axitinib, 0.35 mg/mL axitinib and 0.5 mg/mL axitinib groups. All treatments were administered three times daily for 14 days. Photographs were taken using a slit lamp on days 7 and 14. The area of neovascularization was measured in mm2 , as the percentage of total corneal area and as the percentage of corneal surface covered by sutures (SCS).

RESULTS

On day 14, the CNV area in the control group (31.50 ± 7.47 mm2 ; 115.00 ± 22.55% of the corneal SCS) was larger than that in the 0.02 mg/mL axitinib group (19.20 ± 8.92 mm2 ; 73.89 ± 34.98%), the 0.35 mg/mL axitinib group (8.83 ± 3.92 mm2 ; 31.90 ± 13.59%) and the 0.5 mg/mL axitinib group (5.12 ± 3.97 mm2 ; 18.38 ± 13.65%). Compared with saline, CNV was inhibited 39.04% by 0.02 mg/mL axitinib, 71.96% by 0.35 mg/mL axitinib and 84.73% by 0.5 mg/mL axitinib.

CONCLUSION

Topical administration of the three axitinib concentrations inhibited CNV in rabbits, blocking both vascular endothelial growth factor and platelet-derived growth factor pathways. Axitinib at 0.5 mg/mL induced profound inhibition of corneal angiogenesis.

Prevention of corneal neovascularization by subconjunctival injection of avastin® loaded thermosensitive hydrogels in rabbit model

The antibody avastin® (Ava) has been clinically to treat various intraocular neovascular diseases, but suffering from the rapid clearance and short shelf-life of Ava in the requirement of frequent administration. In the present study, we reports the sustained release of Ava from a thermosensitive hydrogel based on poly(ethylene glycol)-poly(ɛ-caprolactone)-poly(ethylene glycol) (PECE) copolymer for the control of corneal neovascularization in rabbit model. Ava were physically mixed with PECE aqueous solution at 4 °C, and resulting Ava-PECE solution showed a sol-gel transition at physiological temperature (37 °C). In vitro release study indicated that Ava-PECE hydrogel provided a sustained release of Ava up to 28 days and the drug release behavior could be finely modulated by the change of PECE concentration. A single subconjunctival injection of PECE hydrogel hardly caused the change of intraocular pressure and corneal endothelial morphology during the entire study period. Intraocular pharmacokinetic analysis suggested that the Ava-PECE hydrogel provided a relatively higher Ava concentration in cornea over Ava solution up to 14 days. In addition, anti-angiogenic effects of the Ava-PECE hydrogel in a suture-induced corneal neovascularization rabbit model indicated that the Ava-PECE hydrogel treatment exhibited superior anti-angiogenic efficacy over Ava solution treatment by decreasing the area ratio of neovascularization on 17 days. Overall, the proposed Ava-PECE hydrogel acting a sustained drug delivery system might be a promising vehicle for the treatment of corneal neovascularization.

Effectiveness of photodynamic therapy with verteporfin combined with intrastromal bevacizumab for corneal neovascularization in Stevens-Johnson syndrome

PURPOSE

To investigate the effectiveness of combined photodynamic therapy with verteporfin and intrastromal injection of bevacizumab for the treatment of corneal neovascularization in patients with Stevens-Johnson syndrome (SJS).

METHODS

Eight eyes of eight patients with SJS having corneal neovascularization who were refractory to 1% prednisolone instillation received photodynamic therapy with verteporfin (6 mg/m²) combined with intrastromal bevacizumab injection (2.5 mg/0.1 mL). Best-corrected visual acuity and intraocular pressure were assessed, and slit-lamp biomicroscopic examination was performed before treatment and at 1 week and every month. A chronic ocular manifestation score was assigned based on the involvement area or the severity before treatment. The cumulative length of corneal blood vessels and area of corneal neovascularization were measured by anterior segment photographs before and after treatment.

RESULTS

At 3 and 6 months after treatment, all eyes showed regression of corneal neovascularization. Complete regression was achieved in five eyes (62.5%) and partial regression in three eyes (37.5%). Among five patients who were followed up for more than 1 year, two eyes maintained complete regression and one eye maintained partial regression at 1 year. However, two eyes with severe chronic ocular manifestation showed revascularization.

CONCLUSIONS

Combined photodynamic therapy with intrastromal bevacizumab injection can effectively inhibit corneal neovascularization in patients with SJS. However, patients with severe chronic ocular manifestation may exhibit revascularization.

Effects of Combined Photodynamic Therapy and Topical Bevacizumab Treatment on Corneal Neovascularization in Rabbits

PURPOSE

To evaluate the effects of combined photodynamic therapy (PDT) and topical bevacizumab treatment on corneal neovascularization in rabbits.

METHODS

Corneal neovascularization was induced by placing a suture for 7 days in both eyes of 15 rabbits. After suture removal, the right eyes of the rabbits were divided into 3 treatment groups (n = 5 each): group 1, 5 mg/mL bevacizumab eye drops; group 2, PDT at 150 J/cm; and group 3, combined PDT and topical bevacizumab treatment. All 15 left eyes formed a control group. After 2 weeks of treatment, digital photographs were obtained and analyzed to determine the area of corneal neovascularization. The rabbits were then killed to measure vascular endothelial growth factor (VEGF) levels in corneal tissues.

RESULTS

The corneal neovascularization area after treatment was significantly smaller in the 3 treatment groups compared with that in the control group. A significant difference was observed between groups 1 and 2 and group 3, but not between groups 1 and 2. VEGF levels were significantly lower in groups 1 and 3 than in the control group. Although group 2 exhibited relatively higher VEGF levels compared with the control group, the difference was not significant.

CONCLUSIONS

Our results suggest that combined PDT and topical bevacizumab treatment is significantly more effective than monotherapy for the treatment of corneal neovascularization in rabbits. Such quantitative comparison in the laboratory is believed to provide the theoretical basis for clinical application of combined PDT and topical bevacizumab treatment.

Efficacy of Subconjunctival Aflibercept Versus Bevacizumab for Prevention of Corneal Neovascularization in a Rat Model

PURPOSE

We aimed to evaluate the efficacy of subconjunctival aflibercept, a vascular endothelial growth factor trap compound, for the treatment of corneal neovascularization in a rat model.

METHODS

Chemical burn was produced in the central cornea of 31 male Sprague-Dawley rats. Animals were randomized to receive treatment with subconjunctival injection of 0.08 mL aflibercept (25 mg/mL), 0.05 mL bevacizumab (25 mg/mL), or 0.05 mL physiologic saline. Corneal neovascularization was evaluated on postinjury days 1, 3, 7, 9, and 13 by corneal photographs. The rats were killed on day 21 and samples were collected for histological and flat-mount immunofluorescence analyses.

RESULTS

In all rats, vascular sprouting began on day 3, reached maximum density on days 7-9, and spontaneously regressed thereafter. Mean burn area in the central cornea comprised ∼15% of the total corneal area. The aflibercept group had a significantly smaller relative area of neovascularization than both control group (P < 0.05, 12.27 ± 9.91, 29.66 ± 9.96 days 7) and bevacizumab group (P < 0.05, 12.27 ± 9.91, 21.27 ± 8.19 days 7 and 15.5 ± 10.25, 32.38 ± 9.44 days 9; Mann-Whitney test). On histological study, hematoxylin and eosin staining revealed blood vessels extending to the central cornea in the control and bevacizumab groups and limited to the periphery in the aflibercept group. Immunofluorescence study with an endothelial marker revealed a smaller area of staining in the aflibercept group.

CONCLUSIONS

Aflibercept effectively inhibits corneal neovascularization in a rat model of chemical burn-induced neovascularization and warrants further study for potential use in humans.

[Current treatments for corneal neovascularization]

The extension of blood vessels into the normally avascular stroma defines corneal neovascularization. Though this phenomenon, pathophysiological and clinical features are well characterized, therapeutic modalities have been hindered by a lack of safe, efficacious and non-controversial treatments. In this literature review, we focus on available therapeutic options in light of recent evidence provided by animal and clinical studies. First, this review will focus on pharmacological treatments that target angiogenesis. The low cost and market availability of bevacizumab make it the first anti-angiogenic therapy choice, and it has demonstrable efficacy in reducing corneal neovascularization when administered topically or subconjunctivally. However, novel anti-angiogenic molecules targeting the intracellular pathways of angiogenesis (siRNA, antisense oligonucleotides) provide a promising alternative. Laser therapy (direct photocoagulation or photo-dynamic therapy) and fine needle diathermy also find a place in the treatment of stabilized corneal neovascularization alone or in association with anti-angiogenic therapy. Additionally, ocular surface reconstruction using amniotic membrane graft or limbal stem cell transplantation is essential when corneal neovascularization is secondary to primary or acquired limbal deficiency.

[Corneal neovascularisation treatments compared: Subconjunctival bevacizumab injections and/or photodynamic therapy]

PURPOSE

To evaluate and compare the efficacy of subconjunctival bevacizumab injections alone, photodynamic therapy alone and combined treatments for reduction of corneal neovascularization.

METHODS

This study was conducted as a prospective case series. A total of seven eyes of 7 patients with corneal neovascularization caused by ocular surface disorders including fungal infectious keratitis and penetrating keratoplasty were included in the study. Patients were randomized into the three following groups: patients in group A received a single subconjunctival injection of 10mg (0.4mL) of bevacizumab, patients in group B were treated with photodynamic therapy with verteporfin (6mg/m(2)) to the neovascularized area and those in group C received a subconjunctival injection of bevacizumab and photodynamic therapy 7 days later. Morphological changes in neovascularization were evaluated over 6 months using slit-lamp biomicroscopy and digital corneal photography. A computer-assisted semi-automatic analysis of the area of corneal neovascularization was performed with Image J software.

RESULTS

Recession of corneal vessels was observed in all eyes at 1 month post-treatment. The neovascularized surface area in all groups combined showed a decrease in the first month after treatment and this decrease continued up to the 6th month. The surface area of corneal neovascularization decreased by 34.05±8.28% in group A (subconjunctival injection of bevacizumab), by 42.06±28.36% in group B (photodynamic therapy with verteporfin) and by 51.67±18.93% in group C (combined subconjunctival injection of bevacizumab and photodynamic therapy). A combined treatment consisting of a subconjunctival injection followed by a PDT session 7 days later might be more effective for the treatment of corneal neovascularisation. No serious local or systemic adverse events were observed.

CONCLUSIONS

Our medium-term results suggest that combined subconjunctival injection of bevacizumab and photodynamic therapy with verteporfin might be used safely and effectively to reduce corneal neovascularization surface. This combined therapy may show a tendency toward greater efficacy than the individual monotherapies. Controlled prospective randomized multicentric trials with a larger sample size are necessary to assess long-term efficacy and to confirm these results.

Clinico-biochemical correlation of the effect of subconjunctival bevacizumab for corneal neovascularization

PURPOSE

The aim of this study was to evaluate the effect of clinical and biochemical effects of subconjunctival bevacizumab injection in eyes with corneal neovascularization (CNV) due to varied etiologies.

METHODS

This prospective interventional case series included 12 eyes of 12 patients with CNV after failed therapeutic penetrating keratoplasty (4 eyes), viral keratitis (4 eyes), adherent leucoma (2 eyes), and pseudophakic bullous keratopathy (2 eyes). Each eye received 3 doses of 1.25 mg (0.05 mL) of bevacizumab at 1-month intervals. Morphological changes in neovascularization were evaluated at each visit by slit-lamp examination and corneal digital photography. Corneal buttons of 4 eyes that underwent optical penetrating keratoplasty after bevacizumab injections were analyzed for vascular endothelial growth factor (VEGF) expression and were compared with untreated vascularized and normal cadaveric donor corneas.

RESULTS

Of the 12 patients, 10 were males and 2 were females. Four eyes received injections in the early phase of vascularization (<12 weeks of onset) of which 3 showed regression of vessels. Eight eyes received bevacizumab in the mature phase (>12 weeks) of which 5 showed regression. The follow-up ranged from 1 to 16 months. Five eyes underwent optical penetrating keratoplasty after receiving the last dose of bevacizumab and maintained graft clarity with no episodes of rejection over a mean follow-up of 9.8 months. Four of these 5 corneal buttons analyzed for VEGF expression revealed clinically significant lower levels of expression as compared with the vascular untreated corneas. No local or systemic adverse effects were noted in any patient.

CONCLUSIONS

Subconjunctival bevacizumab helps to regress CNV due to a decrease in corneal VEGF levels and might prove beneficial for use in clinical conditions leading to CNV.

Use of topical bevacizumab for conjunctival intraepithelial neoplasia

PURPOSE

To report our experience in the treatment of intraepithelial neoplasia of the conjunctiva using topical bevacizumab.

METHODS

Ten eyes of 10 patients with conjunctival neoplasia received 25 mg/mL bevacizumab topically. Changes in the lesions were documented weekly using digital photography. After topical treatment, excisional biopsy was performed.

RESULTS

The mean age of the patients was 60.5 ± 12 (33-77) years. The mean duration of topical treatment was 7.8 ± 1.3 (5-14) weeks. The size and vascularity of the tumors reduced weekly. All patients underwent excisional biopsy, cryotherapy, and amnion membrane transplantation. The histopathologic diagnosis of the lesions was carcinoma in situ. No recurrence was observed during the follow-up of patients for 6 months.

CONCLUSIONS

Topical bevacizumab is an effective treatment to reduce the tumor size before surgery and may be a good alternative for adjuvant therapy of conjunctival neoplasms.

Early effects of dexamethasone and anti-VEGF therapy in an inflammatory corneal neovascularization model

Inflammatory angiogenesis is the pathogenic mechanism of various sight-threatening eye diseases, among them corneal neovascularization. Current treatment options include steroids which have undesirable side effects, or anti-VEGF which has only limited efficacy. In an inflammatory environment, however, angiogenesis can be stimulated by numerous factors not directly targeted by anti-VEGF therapy. The aim of this study was to induce corneal inflammation leading to angiogenesis, and investigate the early, differential effects of steroid and anti-VEGF therapy at the cellular, tissue, and gene expression levels. Fifty-two Wistar rats received a single intrastromal corneal suture to induce a controlled inflammatory angiogenic response. Rats were subsequently treated with dexamethasone, rat specific anti-VEGF, or goat IgG (control), topically 4 times daily for 7 days. In vivo confocal microscopy of the cornea was performed longitudinally from 5 h up to 7 d to investigate morphology at the cellular and tissue-level. In vivo photographic vessel analysis and immunohistochemistry were also performed. RT-PCR for VEGF-A, FGF-2, IL-6, TNF-α, CXCL2, CCL2, CCL3 and DLL4 was performed at 24 h, and for VEGF-A, IL-6, TNF-α, FGF-2, CXCL2, CCL2, and CCL3 at 7 days. Early infiltration of CD11b + myeloid cells into the cornea at 5 h post-suture was delayed by both treatments relative to controls; however neither treatment was able to suppress accumulation of myeloid cells at day 2 or 7. Limbal vessel dilation was inhibited at 5 h by both treatments, but only dexamethasone showed sustained effect until day 2. Early macrophage recruitment was also suppressed by dexamethasone (but not by anti-VEGF) until day 2. Dexamethasone furthermore suppressed corneal neovascularization at day 7 by over 90%, whereas suppression by anti-VEGF was 14%. Despite differential suppression of vessel dilation, macrophage recruitment, and vascular invasion, anti-VEGF and dexamethasone both down-regulated VEGF-A and IL-6 expression at 24 h with sustained effect to 7 d. They also both down regulated FGF-2 and TNF-α at 24 h and CCL2 at 7 d. In conclusion, anti-angiogenic treatments influence early, pre-angiogenic tissue activity such as limbal vessel dilation, inflammatory cell infiltration of the stroma, and macrophage recruitment. Importantly, the differential effects of steroids and anti-VEGF treatment in suppressing neovascular growth could not be attributed to differential inhibition of several major angiogenic and inflammatory factors in the early pre-sprouting phase, including IL-6, VEGF-A, FGF-2, TNF-α, CCL2, CCL3, CXCL2, or DLL4.

Topical Ranibizumab inhibits inflammatory corneal hem- and lymphangiogenesis

PURPOSE

Ranibizumab (Lucentis(®) ) is a Fab-Fragment of a recombinant, humanized, monoclonal VEGF (anti-vascular endothelial growth factor) antibody. This study analyzed the ability of topical Ranibizumab to inhibit lymphangiogenesis in addition to hemangiogenesis after acute corneal inflammation in vivo. In addition, the effect of Ranibizumab on the proliferation of human lymphatic endothelial cells (LECs) and blood endothelial cells (BECs) in vitro was studied.

METHODS

The inhibitory effect of Ranibizumab on LECs and BECs was studied in vitro using a proliferation enzyme-linked immunosorbent assay (ELISA) assay. To study the in vivo effects of Ranibizumab, the mouse model of suture induced inflammatory corneal neovascularization was used. Study mice received topical Ranibizumab as eye drops. After 1 week excised corneas were stained with LYVE-1 and CD31. Hemangiogenesis and lymphangiogenesis were analyzed morphometrically by using a semiautomatic method based on the image analyzing program Cell^F.

RESULTS

An antiproliferative effect of Ranibizumab was seen in vitro on both human BECs and LECs with a significance of p < 0.0001 and p < 0.0004, respectively. In vivo experiments showed that topical application of Ranibizumab significantly inhibits both hemangiogenesis (p = 0.0026) and lymphangiogenesis (p = 0.0026) in the cornea.

CONCLUSION

Ranibizumab is a potent inhibitor of inflammatory corneal hemangiogenesis and lymphangiogenesis in vivo with a direct inhibitory effect on both endothelial cell types in vitro. This study for the first time demonstrates an inhibitory effect of Ranibizumab on lymphatic vessels which could have a wider range of clinical applications.

Effect of intravitreal injection of bevacizumab-chitosan nanoparticles on retina of diabetic rats

AIM

To investigate the effects of intravitreal injection of bevacizumab-chitosan nanoparticles on pathological morphology of retina and the expression of vascular endothelial growth factor (VEGF) protein and VEGF mRNA in the retina of diabetic rats.

METHODS

Seventy-two 3-month aged diabetic rats were randomly divided into 3 groups, each containing 24 animals and 48 eyes. Both eyes of the rats in group A were injected into the vitreous at the pars plana with 3µL of physiological saline, while in groups B and C were injected with 3µL (75µg) of bevacizumab and 3µL of bevacizumab-chitosan nanoparticles (containing 75µg of bevacizumab), respectively. Immunohistochemistry was used to assess retinal angiogenesis, real-time PCR assay was used to analyse the expression of VEGF mRNA, and light microscopy was used to evaluate the morphology of retinal capillaries.

RESULTS

Real-time PCR assay revealed that the VEGF mRNA expression in the retina before injection was similar to 1 week after injection in group A (P>0.05), while the VEGF mRNA expression before injection significantly differed from those 4 and 8 weeks after injection (P<0.05). Retinal expression of VEGF protein and VEGF mRNA was inhibited 1 week and 4 weeks after injection (P<0.05) in group B, and the expression of VEGF protein and VEGF mRNA was obviously inhibited until 8 weeks after injection (P<0.05) in group C. Using multiple comparisons among group A, group B, and group C, the VEGF expression before injection was higher than at 1, 4 and 8 weeks after injection (P<0.05). The amount of VEGF expression was higher 8 weeks after injection than 1 week or 4 weeks after injection, and also higher 1 week after injection compared with 4 weeks after injection (P<0.05). No toxic effect on SD rats was observed with bevacizumab-chitosan nanoparticles injection alone.

CONCLUSION

The results offer a new approach for inhibiting angiogenesis of diabetic retinopathy and indicate that the intravitreal injection of bevacizumab inhibits VEGF expression in retina, and bevacizumab-chitosan nanoparticles have a longer duration of action.

Subconjunctival bevacizumab injection for ocular surface squamous neoplasia

PURPOSE

To determine the efficacy and safety of perilesional/subconjunctival bevacizumab injections in the management of ocular surface squamous neoplasia (OSSN).

METHODS

Ten eyes of 10 patients with an OSSN diagnosis confirmed by impression cytology received 2 perilesional/subconjunctival injections of bevacizumab at a 2-week interval. Patients were evaluated for 3 months, during which time, changes in the lesions were documented using digital photography. After this period, excisional biopsy of the remaining tumor and cryotherapy of the conjunctival borders were performed if deemed necessary.

RESULTS

The mean age of the patients was 65 ± 12 years (± SD). All of the tumors were nasal in origin and had varying degrees of vascularization. The mean lesion area before treatment was 16 ± 6.9 mm2. Two weeks after the first injection, the mean reduction observed in the tumor area was 25% ± 5.65% and ranged from 17% to 33% (P = 0.001). Two weeks after the second injection, the mean tumor area was further decreased (42% ± 33%, ranging from 15% to 100%, P = 0.049). Corneal extension of the tumor was not affected significantly in 8 of the eyes with concomitant conjunctival and corneal involvement. Complete disappearance of the tumor was demonstrated by impression cytology and occurred in 2 cases involving lesions clinically confined to the conjunctiva. No systemic or ocular side effects occurred during the study period.

CONCLUSIONS

Perilesional/subconjunctival injections of bevacizumab decrease the size and vascularity of OSSN and may be curative in lesions limited to the conjunctiva. However, this treatment has no significant effect on the corneal extension of OSSN.

The effect of subconjunctival ranibizumab on corneal and anterior segment neovascularization: study on an animal model

PURPOSE

To evaluate the effect of subconjunctival anti-vascular endothelial growth factor (VEGF) ranibizumab on corneal and anterior segment neovascularization.

METHODS

In this experimental study and laboratory investigation, chemical cauterization was utilized to induce corneal neovascularization in 16 rabbits randomly divided in 2 equal groups. Cauterized eyes were either treated with 0.1 mL (1 mg) of subconjunctival ranibizumab or administered a sham injection. A third group of 4 rabbits served as control for side effects after ranibizumab administration. All animals were monitored daily for 14 days and the extent of corneal scarring and neovascularization was measured on days 1, 7, and 14. After enucleation, ocular tissues were separated under a surgical microscope and VEGF levels were measured with ELISA. Statistical analysis was performed to compare the extent of corneal neovascularization and VEGF levels between treated and untreated eyes.

RESULTS

Subconjunctival ranibizumab inhibited corneal neovascularization significantly both in the first and the second week compared to untreated controls (p = 0.006 and p = 0.001, respectively). The VEGF levels were significantly lower in all anterior segment tissues like the cornea, iris, aqueous humor, and conjunctiva of the treated eyes (p<0.01). The reduction of VEGF levels ranged from 19% to 73% in different ocular tissues. Corneal scarring was not significantly affected by anti-VEGF treatment (p = 0.7). No side effects were noticed.

CONCLUSIONS

Early subconjunctival administration of ranibizumab may successfully inhibit alkali-induced corneal neovascularization in an animal model. Subconjunctival ranibizumab reduces VEGF levels significantly not only in the cornea and the bulbar conjunctiva but also in the aqueous humor and the iris.

Vascular endothelial growth factor gene polymorphism and protein expression in the pathogenesis of pterygium

BACKGROUND AND AIMS

Vascular endothelial growth factor (VEGF) gene expression has been linked to cancer progression. Here we hypothesise that the polymorphism and protein expression of VEGF are correlated with the pathogenesis and therapy response of pterygium.

METHODS

60 pterygial and 121 normal conjunctival samples were collected to determine the genotypes and protein expression of VEGF. Primary pterygium cells (PECs) were used to confirm the effect of the VEGF polymorphism on the angiogenesis of pterygium.

RESULTS

48 (83.3%) pterygial specimens tested positive for VEGF protein expression, which was significantly higher than in the control groups (16.7%, p<0.0001). The frequency of the 936 C>T variant, but not the -2578C>A variant, was significantly higher in the pterygium group compared with the control group. VEGF protein expression was significantly higher in the 936 C/C group than in the 936 C/T and T/T groups (p=0.001). The results of our cell model showed that PECs with the C/C genotype had a higher angiogenesis ability and higher response to the antiangiogenesis drug bevacizumab than cells with the C/T and T/T genotypes.

CONCLUSIONS

We suggest that VEGF could be used as a target for pterygium therapy in patients with the 936C>T genotype.

Subconjunctival bevacizumab in the impending recurrent pterygia

The aim of this study is to evaluate the efficacy and safety of subconjunctival bevacizumab injection(s) in the treatment of impending recurrent pterygia. Twenty-three eyes of 23 patients who developed impending recurrence after pterygium surgery with conjunctival autografting and were treated with subconjunctival bevacizumab injection(s) (2.5 mg/0.1 mL) were included in the study. Anterior segment photographs were taken prior to and at 1 week, 1, 3 and 6 months after the injection, and at the end of the follow-up period. Image analysis was performed using an image processing and analysis software program. Recurrence rate and complications were recorded. The mean age and follow-up time of the patients were 51.2 ± 6.2 (31-60 years) and 16.8 ± 3.1 (12-22 months), respectively. The average number of injections was 2 ± 0.78 (1-3). Sixteen eyes required re-injection (two injections in nine eyes, three injections in seven eyes), due to progression of vascularization. There were significant differences between size percentage of lesions before injection and at 1 week, 1, 3 and 6 months after the injection (p < 0.05 for all). Corneal recurrence developed in only one patient and no ocular or systemic side-effects of bevacizumab were observed. Repeated injections of bevacizumab may help to prevent the high recurrence rate of residual impending pterygium, due to its adjuvant role in decreasing lesion size, especially in the first year after surgery.

[Imaging and quantification of corneal neovascularization]

Corneal neovascularization is defined as the invasion of vessels into the normally avascular clear corneal stroma, secondary to acute or chronic tissue injury. In addition to decreasing visual acuity, vascularity introduces circulating immune cells, reducing corneal immune privilege and the graft survival of subsequent keratoplasty. Thus, reducing neovascularization has become a recent therapeutic target in order to increase the success of corneal transplantation. Comparing the effects of antiangiogenic drugs assumes that we are able to quantify corneal neovascularization before and after treatment. In the first part of this literature review, we present the various methods to document neovessels (color photos, fluorescein and indocyanine green anterior segment angiography, in vivo confocal microscopy). Next, we report methods to classify and quantify corneal neovascularization.

Effects of subconjunctivally injected bevacizumab, etanercept, and the combination of both drugs on experimental corneal neovascularization

OBJECTIVE

To compare the effect of subconjunctivally injected bevacizumab, etanercept and the combination of both drugs on experimental corneal neovascularization in rats.

DESIGN

Experimental study.

PARTICIPANTS

28 male Wistar-Albino rats.

METHODS

Right corneas of rats were cauterized by silver nitrate sticks. Rats were divided randomly and equally into 4 groups so that each group contained 7 subjects. Immediately after the cauterization, 0.05 ml normal saline was injected subconjunctivally in group 1 (control group); 0.05 ml (1.25 mg) bevacizumab was injected subconjunctivally in group 2; 0.05 ml (1.25 mg) etanercept was injected subconjunctivally in group 3; 0.05 ml (1.25 mg) bevacizumab and 0.05 ml (1.25 mg) etanercept was injected subconjunctivally in group 4. The rats were euthanized on the 8th day, and digital photographs were obtained before the eyes were enucleated. The area of corneal neovascularization was calculated from digital photographs. Corneal sections were analyzed by histopathologically.

RESULTS

The burn stimulus score was +1 or higher in all eyes. The difference of the neovascularization score between groups was found to be statistically significant (p = 0.001). The area of corneal neovascularization was 79.8% in group 1, 43.2% in group 2, 54.5% in group 3, and 34.8% in group 4. In group 4, corneal neovascularization was inhibited more than in the other groups. Histologic examination showed that the treatment groups had less neovascularization, inflammation, and fibroblast activity than the control group (p< 0.05).

CONCLUSIONS

Our study has shown that etanercept does have some antiangiogenic and anti-inflammatory effects in treatment of corneal neovascularization. The combination of bevacizumab and etanercept may be a promising approach in the treatment of corneal neovascularization.

Treatment of corneal neovascularization in ocular chemical injury with an off-label use of subconjunctival bevacizumab: a case report

INTRODUCTION

In this report, we describe the case of a patient with ocular chemical injury, symblepharon, and corneal neovascularization in whom subconjunctival injection of bevacizumab caused regression of corneal opacification and neovascularization, which led to visual improvement.

CASE PRESENTATION

A 54-year-old Caucasian woman presented at our eye emergency department following a splash injury of the left eye with sodium hydroxide. At presentation, her visual acuity was light perception. Slit-lamp examination showed diffuse corneal epithelial defects, stromal edema, and localized Descemet's folds. Despite administration of topical and systemic steroids, she developed symblepharon after 3 months as well as superficial and deep corneal neovascularization with visual acuity 0.5 logarithm of the minimum angle of resolution. A subconjunctival bevacizumab injection (dose 1.25mg/0.05ml) was administered. After 1 week, the vessels appeared thinner and corneal opacity was clearer. Her visual acuity improved to 0.3 logarithm of the minimum angle of resolution. Three weeks later her visual acuity had not changed, and the vessels had started to perfuse again. A second subconjunctival bevacizumab injection was given. After 2 weeks, her vision had improved to 0.1 logarithm of the minimum angle of resolution, vessel regression was observed, and corneal opacity was significantly reduced. Three months after the second injection her vision was unchanged, and the neovascularization remained stable. During the next months, the patient's condition was well-controlled, and, at the end of follow-up 24 months later, her visual acuity and clinical condition were unaltered.

CONCLUSION

Subconjunctival bevacizumab injection may be considered as a second-line treatment of corneal neovascularization caused by chemical injury that is unresponsive to conventional steroid therapy.

Anterior segment uses of bevacizumab

PURPOSE OF REVIEW

A significant recent advancement in the treatment of neovascularization of the anterior segment of the eye is the development of antivascular endothelial growth factor (anti-VEGF) therapeutic agents.We present a review of the current knowledge on anti-VEGF therapy with bevacizumab for anterior segment neovascularization.

RECENT FINDINGS

A review of the recent peer-reviewed literature reveals an increasing number of experimental and clinical studies on the use of Avastin in both human and animal eye models. Although the numbers are still relatively small, the evidence suggests that bevacizumab may be effective in the treatment of corneal and iris neovascularization. Its effect on primary and recurrent pterygium is more controversial. In general, achievement of vessels regression is usually partial, and recurrence may occur after cessation of treatment. Response to treatment is affected by the chronicity of vessels, their extent, the cause for blood vessels formation, and the route of administration.

SUMMARY

Effective short-term response together with high patient tolerance to local bevacizumab therapy offer encouraging results for the management of anterior segment neovascular disorders. Although statistically significant regression of vessels has been documented in many studies, the clinical significance of this finding is still a subject of debate.

The effect of different doses of subconjunctival bevacizumab injection on corneal neovascularization

To evaluate the effects of various doses of subconjunctival bevacizumab injections in the treatment of patients with corneal neovascularization. During the 6-month-follow-up, no significant ocular or systemic adverse events were observed related to the subconjunctival bevacizumab injection. In Group 1, the total area of corneal neovascularization before injection was 14.8 ± 3.2 % of the corneal surface and 10.2 ± 2.8 % 6 months after injection (p < 0.01). The mean decrease in Group 1 was 32.0 ± 3.0 %. In Group 2, the total area of corneal neovascularization before and 6 months after the injection was 14.2 ± 2.5 and 9.8 ± 2.3 %, respectively (p < 0.01). The mean decrease in Group 2 was 31.0 ± 2.3 %. The difference between the two groups was not statistically significant (p > 0.05). Twenty-four eyes of 24 patients with corneal neovascularization who were treated with a subconjunctival injection of bevacizumab were included in this retrospective study. Fourteen eyes were treated with 2.5 mg/0.1 ml (Group 1), and 10 eyes were treated with 5.0 mg/0.2 ml (Group 2) of subconjunctival bevacizumab. Digital photographs of the cornea were used to determine the area of corneal neovascularization before injection and at 1 month, 3 months, and 6 months after treatment. Subconjunctival injection of bevacizumab is well tolerated and associated with a partial regression of corneal neovascularization. The efficacy of this treatment is not correlated to the injection dose.

The association between corneal neovascularization and visual acuity: a systematic review

PURPOSE

Corneal neovascularization (CNV) is thought to negatively influence visual acuity. New therapeutic options that offer a differentiated influence on the ingrowths or regression of either corneal blood or lymphatic vessels force us to re-evaluate the association between CNV and visual acuity.

METHODS

A systematic review was conducted. Electronic databases were searched up to August 2009. Given the heterogeneity in study populations, interventions and measures of association, we were unable to undertake meta-analysis. The association between CNV and visual acuity was reported descriptively for each study.

RESULTS

Eleven studies using either vascular endothelial growth factor inhibitor treatments (i.e. bevacizumab, Avastin(®) ; Hoffmann-La Roche AG, Basel, Switzerland) or an antiangiogenic treatment based on IRS-1 modulation [Gene-Signal (GS) 101, Aganirsen(®) ; GeneSignal, Evry (Paris), France] in a total of 131 patients (142 eyes) with corneal neovascularization were included. Ten of the eleven studies reported evidence of a statistically significant reduction in neovascularization following treatment. However, only four studies reported a statistically significant improvement in visual acuity following therapy. We found no studies that assessed the patient-level association between the change in neovascularization and visual acuity.

CONCLUSION

This systematic review found that there is currently weak evidence to support the hypothesis that in patients with pathological neovascularization, a treatment-related reduction in neovascularization is associated with an increase in visual acuity. There is a need for future appropriately designed studies.