Vascular Endothelial Growth Factor Inhibitors for Treatment of Corneal Neovascularization: A Meta-Analysis

Subconjunctival aflibercept inhibits corneal angiogenesis and VEGFR-3+CD11b+ cells

PURPOSE

This study aimed to investigate the effects of subconjunctival injection of aflibercept, a soluble protein decoy for VEGFR-1 and VEGFR-2, on corneal angiogenesis and VEGFR-expressing CD11b+ cells in a mouse model of suture-induced corneal neovascularization.

METHODS

Corneal neovascularization was induced in BALB/c mice by placing three sutures on the cornea. Immediately after surgery, either 200 µg aflibercept (5 µL) or an equal volume of phosphate-buffered saline (PBS) was administered into the subconjunctival space. Seven days after later, corneal new vessels were quantified through clinical examination and measurement of the CD31-stained area in corneal flat mounts. The levels of pro-angiogenic and inflammatory markers in the cornea were evaluated using RT-qPCR. The percentages of VEGFR-2+CD11b+ cells and VEGFR-3+CD11b+ cells were analyzed in the cornea, blood, and draining cervical lymph nodes (DLNs) using flow cytometry.

RESULTS

Subconjunctival injection of aflibercept significantly reduced the growth of corneal new vessels compared to subconjunctival PBS injection. The mRNA levels of Cd31, vascular growth factors (Vegfc and Angpt1), and pro-angiogenic/inflammatory markers (Tek/Tie2, Mrc1, Mrc2, and Il6) in the cornea were downregulated by subconjunctival aflibercept. Also, the percentage of VEGFR-3+CD11b+ cells in the cornea, blood, and DLNs was decreased by aflibercept, whereas that of VEGFR-2+CD11b+ cells was unaffected.

CONCLUSION

Subconjunctival aflibercept administration inhibits inflammatory angiogenesis in the cornea and reduces the numbers of cornea-infiltrating and circulating VEGFR-3+CD11b+ cells.

Shark Cartilage-Derived Anti-Angiogenic Peptide Inhibits Corneal Neovascularization

Corneal neovascularization is a significant cause of vision loss, often resulting in corneal clouding and chronic inflammation. Shark cartilage is widely recognized as a significant natural source of anti-angiogenic compounds. Our previous studies have shown that a polypeptide from white-spotted catshark (Chiloscyllium plagiosum Bonnet) has the potential to inhibit the angiogenesis of breast tumors. This study applied this peptide (SAIF) to a corneal alkali injury model to assess its effect on corneal neovascularization. Results revealed that SAIF inhibits endothelial cell proliferation, migration, and tube formation. SAIF inhibited VEGF-induced angiogenesis in the matrigel plug. Using the corneal alkali injury model, SAIF significantly inhibited corneal vascular neovascularization in mice. We found that SAIF not only significantly inhibited the upregulation of pro-angiogenic factors such as VEGF, bFGF, and PDGF expression induced by alkali injury, but also promoted the expression of anti-angiogenesis factor PEDF. Moreover, we also analyzed the MMPs and TIMPs involved in extracellular matrix (ECM) remodeling, angiogenesis, and lymphangiogenesis. We found that SAIF treatment inhibited the expression of pro-angiogenic factors like MMP1, MMP2, MMP3, MMP9, MMP13, and MMP14, and promoted the expression of anti-angiogenesis factors such as MMP7, TIMP1, TIMP2, and TIMP3. In conclusion, SAIF acts as an anti-angiogenic factor to inhibit the proliferation, migration, and tube formation of endothelial cells, inhibit pro-angiogenic factors, promote anti-angiogenic factors, and regulate the expression of MMPs, ultimately inhibiting corneal neovascularization.

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.

Efficacy and safety of anti-vascular endothelial growth factor agents on corneal neovascularization: A meta-analysis

BACKGROUND

Corneal neovascularization (CoNV) is the second major cause of blindness. Vascular endothelial growth factor (VEGF) inhibitors, e.g., bevacizumab, have been used to prevent CoNV.

AIM

We conducted an updated systematic review and meta-analysis of clinical trials to examine the efficacy and safety of anti-VEGF in CoNV.

METHODS

A literature search was conducted using three electronic databases. Mean difference (MD), standard mean difference (SMD), and relative risk (RR) are used to estimate the effect size.

RESULTS

Nine randomized controlled and three non-randomized trials were obtained. The pooled results demonstrated a significant reduction of CoNV area/Length (SMD = -1.17, 95%CI: -1.58 to -0.75), best corrected visual acuity (MD = -0.54, 95%CI: -0.91 to -0.17), and graft rejection (RR = 0.44, 95%CI: 0.24 to 0.8) and failure (RR = 0.39, 95%CI: 0.19 to 0.78) rates in the anti-VEGF group than the placebo group. A non-significant reduction of the epithelial defect was also observed in the bevacizumab group compared with the placebo (RR = 0.56, 95%CI: 0.30 to 1.06). Compared with a placebo, the unsynthesizable trials also support that bevacizumab improves visual acuity, CoNV, graft rejection, and failure rates. Trials reporting other comparisons revealed the superiority of combined remedy with bevacizumab compared to other treatments in reducing CoNV.

CONCLUSION

Anti-VEGF agents, mainly bevacizumab, are an effective and safe treatment for CoNV of all causes and prevent corneal graft rejection and failure in corneal transplantation.

Overactivation of Norepinephrine-β2-Adrenergic Receptor Axis Promotes Corneal Neovascularization

Purpose

To investigate the role of the sympathetic nervous system in corneal neovascularization (CNV) and to identify the downstream pathway involved in this regulation.

Methods

Three types of CNV models were constructed with C57BL/6J mice, including the alkali burn model, suture model, and basic fibroblast growth factor (bFGF) corneal micropocket model. Subconjunctival injection of the sympathetic neurotransmitter norepinephrine (NE) was administered in these three models. Control mice received injections of water of the same volume. The corneal CNV was detected using slit-lamp microscopy and immunostaining with CD31, and the results were quantified by ImageJ. The expression of β2-adrenergic receptor (β2-AR) was stained with mouse corneas and human umbilical vein endothelial cells (HUVECs). Furthermore, the anti-CNV effects of β2-AR antagonist ICI-118,551 (ICI) were examined with HUVEC tube formation assay and with a bFGF micropocket model. Additionally, partial β2-AR knockdown mice (Adrb2+/-) were used to establish the bFGF micropocket model, and the corneal CNV size was quantified based on the slit-lamp images and vessel staining.

Results

Sympathetic nerves invaded the cornea in the suture CNV model. The NE receptor β2-AR was highly expressed in corneal epithelium and blood vessels. The addition of NE significantly promoted corneal angiogenesis, whereas ICI effectively inhibited CNV invasion and HUVEC tube formation. Adrb2 knockdown significantly reduced the cornea area occupied by CNV.

Conclusions

Our study found that sympathetic nerves grow into the cornea in conjunction with newly formed vessels. The addition of the sympathetic neurotransmitter NE and activation of its downstream receptor β2-AR promoted CNV. Targeting β2-AR could potentially be used as an anti-CNV strategy.

An Update on Novel Ocular Nanosystems with Possible Benefits in the Treatment of Corneal Neovascularization

Corneal neovascularization (CNV) is an ocular pathological change that results from an imbalance between angiogenic factors and antiangiogenic factors as a result of various ocular insults, including infection, inflammation, hypoxia, trauma, corneal degeneration, and corneal transplantation. Current clinical strategies for the treatment of CNV include pharmacological treatment and surgical intervention. Despite some degree of success, the current treatment strategies are restricted by limited efficacy, adverse effects, and a short duration of action. Recently, gene-based antiangiogenic therapy has become an emerging strategy that has attracted considerable interest. However, potential complications with the use of viral vectors, such as potential genotoxicity resulting from long-term expression and nonspecific targeting, cannot be ignored. The use of ocular nanosystems (ONS) based on nanotechnology has emerged as a great advantage in ocular disease treatment during the last two decades. The potential functions of ONS range from nanocarriers, which deliver drugs and genes to target sites in the eye, to therapeutic agents themselves. Various preclinical studies conducted to date have demonstrated promising results of the use of ONS in the treatment of CNV. In this review, we provide an overview of CNV and its current therapeutic strategies and summarize the properties and applications of various ONS related to the treatment of CNV reported to date. Our goal is to provide a comprehensive review of these considerable advances in ONS in the field of CNV therapy over the past two decades to fill the gaps in previous related reports. Finally, we discuss existing challenges and future perspectives of the use of ONS in CNV therapy, with the goal of providing a theoretical contribution to facilitate future practical growth in the area.

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.

The functional role of decorin in corneal neovascularization in vivo

Our earlier decorin (Dcn) gene overexpression studies found that the targeted Dcn gene transfer into the cornea inhibited corneal angiogenesis in vivo using a rabbit model. In this study, we tested the hypothesis that anti-angiogenic effects of decorin in the cornea are mediated by alterations in a normal physiologic balance of pro- and anti-angiogenic factors using decorin deficient (Dcn^-/-) and wild type (Dcn^+/+) mice. Corneal neovascularization (CNV) in Dcn^-/- and Dcn^+/+ mice was produced with a standard chemical injury technique. The clinical progression of CNV in mice was monitored with stereo- and slit-lamp microscopes, and histopathological hematoxylin and eosin (H&E) staining. Protein and mRNA expression of pro- and anti-angiogenic factors in the cornea were evaluated using immunofluorescence and quantitative real-time PCR, respectively. Slit-lamp clinical eye examinations revealed significantly more CNV in Dcn^-/- mice than the Dcn^+/+ mice post-injury (p < 0.05) and AAV5-Dcn gene therapy significantly reduced CNV in Dcn^-/- mice compered to no AAV5-Dcn gene therapy controls (p < 0.001). H&E-stained corneal sections exhibited morphology with several neovessels in injured corneas of the Dcn^-/- mice than the Dcn^+/+ mice. Immunofluorescence of corneal sections displayed significantly higher expression of α-smooth muscle actin (α-SMA) and endoglin proteins in Dcn^-/- mice than Dcn^+/+ mice (p < 0.05). Quantitative real-time PCR found significantly increased mRNA levels of pro-angiogenic factors endoglin (2.53-fold; p < 0.05), Vegf (2.47-fold; p < 0.05), and Pecam (2.14-fold; p < 0.05) and anti-angiogenic factor Vegfr2 (1.56-fold; p < 0.05) in the normal cornea of the Dcn^-/- mice than the Dcn^+/+ mice. Furthermore, neovascularized Dcn^-/- mice corneas showed greater increase in mRNA expression of pro-angiogenic factors endoglin (4.58-fold; p < 0.0001), Vegf (4.16-fold; p < 0.0001), and Pdgf (2.15-fold; p < 0.0001) and reduced expression of anti-angiogenic factors Ang2 (0.12-fold; p < 0.05), Timp1 (0.22-fold; p < 0.05), and Vegfr2 (0.67-fold; p > 0.05) compared to neovascularized Dcn^+/+ mice corneas. These gene deficience studies carried with transgenic Dcn^-/- mice revealed decorin's role in influencing a physiologic balance between pro-and anti-angiogenic factors in the normal and injured cornea. We infer that the functional deletion of Dcn promotes irregular corneal repair and aggravates CNV.

Novel Parameters to Assess the Severity of Corneal Neovascularization Using Anterior Segment Optical Coherence Tomography Angiography

PURPOSE

Assessment of anterior segment-optical coherence tomography angiography (AS-OCTA) to determine severity of corneal neovascularization (CoNV).

DESIGN

Retrospective, cross-sectional, single-center study.

METHODS

Patients of various CoNV etiologies were selected and classified into mild, moderate, and severe. Their AS-OCTA images were measured for CoNV anterior limit, CoNV posterior limit, CoNV thickness, CoNV depth%, CoNV vessel density, CoNV area, and CoNV volume. Further, AS-OCTA parameters were correlated to clinical parameters, such as classification, a numerical severity scale, vascular clock hours, and best-corrected visual acuity (BCVA).

RESULTS

A total of 19 mild, 10 moderate, and 6 severe CoNV eyes were included with no significant age-gender differences. CoNV depth% and volume increased from mild to moderate (9.3 ± 1.1% to 17.7 ± 3.3%, P = .030, and 0.2 ± 0.1 mm³ to 1.0 ± 0.3 mm³, P = .025, respectively) and from moderate to severe CoNV (44.6 ± 5.3%, P < .001, and 2.0 ± 0.3 mm³, P = .014, respectively). CoNV area and posterior limit increased from mild to moderate (1.7 ± 0.3 mm² to 4.6 ± 0.7 mm², P = .001, and 217.7 ± 16.8 μm to 349.1 ± 54.9 μm, P = .048, respectively), not from moderate to severe (P = .999 and P = .403, respectively). CoNV thickness increased from moderate to severe (218.2 ± 46.6 μm to 340.2 ± 8.7 μm, P = .020), but not from mild to moderate. CoNV area and volume showed good correlations to CoNV staging (r = 0.703 and r = 0.771, respectively; P < .001) and severity scale (r = 0.794 and r = 0.712, respectively; P < .001). CoNV area showed good correlation to clock hours (r = 0.749, P < .001). CoNV depth and volume showed good correlation to BCVA (r = 0.744 and r = 0.722, respectively; P < .001). CoNV anterior limit and vessel density showed no significant correlations (P ≥ .05).

CONCLUSIONS

Severe CoNV shows greater CoNV posterior limit, thickness, depth%, area, and volume on AS-OCTA compared to mild. CoNV volume and depth strongly correlate to BCVA. AS-OCTA provides novel, quantitative, and noninvasive parameters for assessing CoNV severity.

Resolution of Refractory Corneal Neovascularization with Subconjunctival Bevacizumab

Corneal neovascularization (CNV) has a variety of causes and threatens corneal clarity, thus optimal visual acuity. Conventional medical management includes topical steroids and matrix metalloproteinase inhibitors like doxycycline. Anti-vascular endothelial growth factor (anti-VEGF) agents have demonstrated promise but remain off-label for this indication. However, these agents hold value in cases refractory to first-line medical management. We report the case of a 63-year-old woman who presented with ocular rosacea and CNV affecting vision, on a background of acne rosacea. She was initially treated with fluorometholone and doxycycline, yet continued to deteriorate. Eventually she received two 1.5-mg subconjunctival injections of bevacizumab 2 months apart. CNV completely resolved and results were maintained at 4-year follow-up. This case demonstrates that refractory CNV can be effectively treated with subconjunctival injection of anti-VEGF bevacizumab. The resolution of CNV was also maintained years after injection with minimal adjunctive therapy during this period, and to our knowledge there are no other studies reporting a follow-up period of 4 years after treatment. This is a pertinent case for other clinicians treating patients in a similar situation.

Lipid Keratopathy: A Review of Pathophysiology, Differential Diagnosis, and Management

Lipid keratopathy is a disease in which fat deposits accumulate in the cornea, leading to opacification and decrease of visual acuity. This condition can be idiopathic without signs of previous corneal disease or secondary to ocular or systemic diseases. Lipid keratopathy is usually associated with abnormal vascularization of the cornea, and the lipid classically deposits adjacent to these vessels. Treatment of this condition usually aims to eliminate or prevent abnormal vessel formation, and several modalities have been described. In this review we summarize the etiology, pathophysiology, and clinical presentation of lipid keratopathy and describe current and emerging treatment regimens.

Corneal neovascularization

The optical clarity of the cornea is essential for maintaining good visual acuity. Corneal neovascularization, which is a major cause of vision loss worldwide, leads to corneal opacification and often contributes to a cycle of chronic inflammation. While numerous factors prevent angiogenesis within the cornea, infection, inflammation, hypoxia, trauma, corneal degeneration, and corneal transplantation can all disrupt these homeostatic safeguards to promote neovascularization. Here, we summarize its etiopathogenesis and discuss the molecular biology of angiogenesis within the cornea. We then review the clinical assessment and diagnostic evaluation of corneal neovascularization. Finally, we describe current and emerging therapies.

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.

Update on the pathogenesis and management of ocular rosacea: an interdisciplinary review

PURPOSE

Rosacea is one of the most common conditions affecting the ocular surface. The purpose of this review is to provide an update on the pathogenesis and treatment of rosacea based on the dermatology and ophthalmology literatures.

METHODS

Literature searches were conducted for rosacea and ocular rosacea. Preference was given to systematic reviews, meta-analysis, case-controlled studies, and documented case reports while excluding poorly documented case studies and commentaries. The data were examined and independently analyzed by more than two of the authors.

RESULTS

Rosacea is a complex inflammatory condition involving the pilosebaceous unit. Its underlying mechanism involves an interplay of the microbiome, innate immunity, adaptive immunity, environmental triggers, and neurovascular sensitivity. The latest classification of rosacea includes three dermatologic subgroups and a fourth subgroup, ocular rosacea. Ocular rosacea clinically displays many features that are analogous to the cutaneous disease, such as lid margin telangiectasia and phlyctenulosis. The role of environmental triggers in the exacerbation of ocular rosacea appears to be understudied. While lid hygiene and systemic treatment with tetracycline drugs remain the mainstay of treatment for ocular rosacea, newer dermatologic targets and therapies may have potential application for the eye disease.

CONCLUSIONS

Ocular rosacea appears to embody many of the manifestation of the dermatologic disease. Hence, the basic pathophysiologic mechanisms of the ocular and cutaneous disease are likely to be shared. Better understanding of the ocular surface microbiome and the immunologic mechanisms, may lead to novel approaches in the management of ocular rosacea.

Regulation of matrix metalloproteinases 2 and 9 in corneal neovascularization

Corneal neovascularization (CNV), a pathological process of angiogenesis, can lead to serious consequences in the cornea. CNV is generally proved to associate with inflammation in the cornea closely, which is mainly elicited by the disruption of equilibrium between angiogenic and antiangiogenic factors. Angiogenic factors including vascular endothelial growth factors (VEGFs), basic fibroblast growth factors (bFGFs), and matrix metalloproteinases (MMPs) are vital factors in the formation of CNV. Especially VEGFs are convinced to be the core angiogenic factors in CNV, and MMPs are proved to exert dual effects on the process. Strikingly, matrix metalloproteinase 2 (MMP-2) and matrix metalloproteinase 9 (MMP-9) are determined to play key roles in the formation of CNV, while the mechanism is still vague. In this review, the latest researches are reviewed to discuss the role of MMP-2 and MMP-9 in CNV, respectively, and some inhibitors of them are presented. We hope to provide a new direction of drug research for CNV.

Micelle-solubilized axitinib for ocular administration in anti-neovascularization

The development of new blood vessels is directly related to the occurrence of eye diseases. Anti-angiogenic drugs can theoretically be extended to the treatment of ophthalmic diseases. In this study, axitinib, a class of tyrosine kinase inhibitors, was loaded via the amphiphilic copolymer MPEG-PCL, improving its dispersibility in water. Axitinib-loaded micelles showed low toxicity in concentration gradient assays. Additionally, multiple doses by scratch assay confirmed that axitinib had no significant effect on normal cell migration, and biosafety test results showed good cell compatibility. After we established the corneal neovascularization model after an alkali burn in rats, the anti-angiogenic efficacy was tested, with dexamethasone as a positive control. The results showed that axitinib-loaded micelles had anti-angiogenic effects without obvious tissue toxicity. As a class of targeted tyrosine kinase inhibitors, axitinib can be used in the treatment of ocular neovascular diseases through nanocrystallization.

Long-term outcome of using Prosthetic Replacement of Ocular Surface Ecosystem (PROSE) as a drug delivery system for bevacizumab in the treatment of corneal neovascularization

PURPOSE

To report the long-term outcome of Prosthetic Replacement of the Ocular Surface Ecosystem (PROSE) for delivery of bevacizumab in the treatment of corneal neovascularization (KNV).

METHODS

Retrospective, non-comparative, interventional case series of 13 sequential patients treated for KNV at the BostonSight between 2006 and 2017. In all cases, PROSE treatment was initiated for management of ocular surface disease and patients wore PROSE consistently on a daily wear basis prior to bevacizumab treatment. Patients applied a drop of 1% preservative free bevacizumab to the reservoir of PROSE device twice daily. Patients continued with daily wear of the device during treatment and afterwards.

RESULTS

13 patients (8 female and mean age of 45 years) are included with a mean follow-up of 5.1 years (range 6 months-11 years). Underlying ocular diagnoses included Stevens-Johnson syndrome (7), ocular chronic graft-versus-host disease (2), corneal transplant (2), contact lens-related corneal ulcer and limbal stem cell deficiency (1), and familial dysautonomia (1). Median duration of bevacizumab use was 6 months (range 3 months-10 years). Twelve cases (92%) had regression of KNV and 10 cases (77%) had improved best-corrected visual acuity (BCVA) with treatment. Median BCVA improved from -1.1 (LogMAR) at baseline, to -0.66 at end of bevacizumab treatment, and remained -0.63 at last follow-up (P = 0.047). KNV progressed in one eye after discontinuation of bevacizumab. There were no ophthalmic or systemic complications.

CONCLUSIONS

Topical bevacizumab used in PROSE is effective in treating KNV and improving vision. Long-term follow-up reveals durable response and no complications.

Current and emerging therapies for corneal neovascularization

The cornea is unique because of its complete avascularity. Corneal neovascularization (CNV) can result from a variety of etiologies including contact lens wear; corneal infections; and ocular surface diseases due to inflammation, chemical injury, and limbal stem cell deficiency. Management is focused primarily on the etiology and pathophysiology causing the CNV and involves medical and surgical options. Because inflammation is a key factor in the pathophysiology of CNV, corticosteroids and other anti-inflammatory medications remain the mainstay of treatment. Anti-VEGF therapies are gaining popularity to prevent CNV in a number of etiologies. Surgical options including vessel occlusion and ocular surface reconstruction are other options depending on etiology and response to medical therapy. Future therapies should provide more effective treatment options for the management of CNV.

Update on the Management of High-Risk Penetrating Keratoplasty

PURPOSE OF REVIEW

In this article, we review the indications and latest management of high-risk penetrating keratoplasty.

RECENT FINDINGS

Despite the immune-privilege status of the cornea, immune-mediated graft rejection still remains the leading cause of corneal graft failure. This is particularly a problem in the high-risk graft recipients, namely patients with previous graft failure due to rejection and those with inflamed and vascularized corneal beds. A number of strategies including both local and systemic immunosuppression are currently used to increase the success rate of high-risk corneal grafts. Moreover, in cases of limbal stem cell deficiency, limbal stem cells transplantation is employed.

SUMMARY

Corticosteroids are still the top medication for prevention and treatment in cases of corneal graft rejection. Single and combined administration of immunosuppressive agents e.g. tacrolimus, cyclosporine and mycophenolate are promising adjunctive therapies for prolonging graft survival. In the future, cellular and molecular therapies should allow us to achieve immunologic tolerance even in high-risk grafts.

Effect of trapping vascular endothelial growth factor-A in a murine model of dry eye with inflammatory neovascularization

AIM

To evaluate whether trapping vascular endothelial growth factor A (VEGF-A) would suppress angiogenesis and inflammation in dry eye corneas in a murine corneal suture model.

METHODS

We established two groups of animals, one with non-dry eyes and the other with induced dry eyes. In both groups, a corneal suture model was used to induce inflammation and neovascularization. Each of two groups was again divided into three subgroups according to the treatment; subgroup I (aflibercept), subgroup II (dexamethasone) and subgroup III (phosphate buffered saline, PBS). Corneas were harvested and immunohistochemical staining was performed to compare the extents of neovascularization and CD11b+ cell infiltration. Real-time polymerase chain reaction was performed to quantify the expression of inflammatory cytokines and VEGF-A in the corneas.

RESULTS

Trapping VEGF-A with aflibercept resulted in significantly decreased angiogenesis and inflammation compared with the dexamethasone and PBS treatments in the dry eye corneas (all P<0.05), but with no such effects in non-dry eyes. The anti-inflammatory and anti-angiogenic effects of VEGF-A trapping were stronger than those of dexamethasone in both dry eye and non-dry eye corneas (all P<0.05). The levels of RNA expression of VEGF-A, TNF-alpha, and IL-6 in the aflibercept subgroup were significantly decreased compared with those in the PBS subgroup in the dry eye group.

CONCLUSION

Compared with non-dry eye corneas, dry eye corneas have greater amounts of inflammation and neovascularization and also have a more robust response to anti-inflammatory and anti-angiogenic agents after ocular surface surgery. Trapping VEGF-A is effective in decreasing both angiogenesis and inflammation in dry eye corneas after ocular surface surgery.

Differential Effects of Bevacizumab, Ranibizumab, and Aflibercept on the Viability and Wound Healing of Corneal Epithelial Cells

PURPOSE

This study compared the effects of 3 antivascular endothelial growth factor (VEGF) agents (bevacizumab, ranibizumab, and aflibercept) on corneal epithelial cell viability and wound healing using human corneal epithelial cells (HCECs).

METHODS

To determine the cytotoxic effects of anti-VEGF agents on HCECs, HCEC viability was determined at various concentrations of these agents. An in vitro migration assay was used to investigate the migration of HCECs treated with 3 anti-VEGF agents. The protein level of extracellular signal-regulated kinase was used to evaluate the effect of anti-VEGF treatment on cell proliferation. The protein levels of p38 mitogen-activated protein kinase (MAPK) were analyzed by Western blotting to investigate cell migration.

RESULTS

After 24 or 48 h of exposure, aflibercept treatment showed no apparent effect on cell viability; however, bevacizumab and ranibizumab treatment decreased cell viability at high concentrations (1 and 2 mg/mL). A migration assay showed that HCEC migration was different among the 3 anti-VEGF treatment groups. Bevacizumab significantly delayed HCEC migration. Western blotting showed that bevacizumab treatment decreased the expression levels of phosphorylated p38 MAPK.

CONCLUSIONS

Bevacizumab, the most widely used and investigated anti-VEGF agent, decreased epithelial cell migration and viability. Anti-VEGF agents other than bevacizumab might therefore be better for treating corneal neovascularization complicated with epithelial defects.

Four years of corneal keratoplasty in Italian paediatric patients: indications and clinical outcomes

PURPOSE

The purpose was to evaluate indications and clinical outcomes in paediatric corneal keratoplasty.

METHODS

Fifty-four eyes of 43 patients who underwent corneal keratoplasty from the 1^st of January 2010 through the 31^st of December 2013 at the Bambino Gesù Children's Hospital in Rome, Italy, were retrospectively evaluated. To assess the effect of age on graft failure rate, the recipient age was considered as a dichotomous variable (≤5 or >5 years) and a 2X2 table was developed, using the chi-square test for testing the statistical significance. Furthermore, two separate subgroup analyses were conducted on patients of ≤5 years and those of >5 years, to evaluate the effect of penetrating keratoplasty (PK) or deep anterior lamellar keratoplasty (DALK) on the graft failure rate. The level of statistical significance was set at p < 0.05 RESULTS: Mean recipient age was 8.9 ± 5.7 [SD] years. Mean follow-up time was 22.8 months. Main preoperative diagnoses were keratoconus (37 %) and congenital glaucoma (20 %). Patients ≤5 years showed a higher percentage of graft failure (p = 0.0008). PK and DALK did not show statistically significant differences regarding the graft failure in both subgroups (p = 0.15 for ≤5 years group and p = 0.27 for >5 years group, respectively). However, across groups DALK provided a lower rate of graft failure.

CONCLUSIONS

Our findings suggest that children older than 5 years show a significantly better graft outcome and that DALK seems to offer greatest benefits in terms of failure risk in paediatric patients.

Inhibitory Effect of Topical Aflibercept on Corneal Neovascularization in Rabbits

PURPOSE

To examine the inhibitory effect of topical aflibercept [vascular endothelial growth factor (VEGF) trapR1R2] on corneal neovascularization (NV) in rabbits.

METHODS

Corneal NV was induced in 24 eyes of 12 rabbits. Seven days after a silk suture in the corneal stroma, the rabbits were divided into 4 groups of 6 eyes each. Two groups were treated with topical aflibercept at 2 different concentrations: 2 mg/0.5 mL (0.1%, group 1) and 2 mg/5 mL (0.01%, group 2). The other 2 groups were treated with topical bevacizumab 2.5 mg/1 mL (0.1%, group 3) and topical balanced salt solution (group 4, control). The concentration of VEGF and placental growth factor (PIGF) messenger RNA (mRNA) was measured by reverse transcriptase-polymerase chain reaction.

RESULTS

The surface area of NV was significantly smaller in the treatment groups compared with that of the control group. The expression of VEGF mRNA was 0.227 in 0.1% aflibercept (group 1), 0.811 in 0.01% aflibercept (group 2), and 0.495 in 0.1% bevacizumab (group 3). There was a significant decrease in the VEGF concentration in all 3 treatment groups compared with the control group, 1.491 (P = 0.031, <0.05). In the 0.01% aflibercept group, the difference was less than that of the 0.1% aflibercept and 0.1% bevacizumab groups. There was no significant difference in the 0.1% aflibercept and 0.1% bevacizumab groups. The expression of PIGF mRNA was 0.791 in 0.1% aflibercept (group 1), 0.743 in 0.01% aflibercept (group 2), 1.194 in 0.1% bevacizumab (group 3), and 1.458 in the control group. The expression of PIGF mRNA was significantly decreased in the 0.1% aflibercept and 0.01% aflibercept groups.

CONCLUSIONS

Topical aflibercept may have an inhibitory effect on corneal NV in rabbits.

Corneal Fine Needle Diathermy With Adjuvant Bevacizumab to Treat Corneal Neovascularization in Children

PURPOSE

To report the outcomes of corneal fine needle diathermy (FND) with adjuvant intrastromal and subconjunctival bevacizumab injection for corneal neovascularization (CN) in children.

METHODS

Medical records of all children who had undergone FND with adjuvant bevacizumab injection were reviewed retrospectively. Treatment efficacy was evaluated by changes in visual acuity, regression of CN, and clearing of lipid deposits with the aid of slit-lamp color images that were taken before surgical intervention and at last follow-up visit. Postoperative complications were recorded and served to assess the safety of the procedure.

RESULTS

Nine eyes of 9 patients were included in the study. The mean age of the patients was 8.4 ± 4.2 years (4-15 years) and the mean follow-up time was 18.7 ± 12.2 months (5-35 months). Three eyes had a history of herpes simplex keratitis (HSK), 3 eyes had complete corneal anesthesia, 2 eyes had CN following suture tract infection after corneal transplant for HSK scar and limbal dermoid excision, and 1 eye had blepharokeratoconjunctivitis. After treatment, 8 eyes had complete CN resolution, and 1 eye with corneal anesthesia following brain tumor resection had partial regression in vessel distribution and size. Lipid deposition clearance lagged behind CN resolution. Mean duration of CN before treatment was 15.3 ± 14.0 months (1-37 months). Mean corrected distance visual acuity before and after surgery was 0.66 ± 0.31 and 0.50 ± 0.37 logMAR, respectively (P = 0.02).

CONCLUSIONS

Corneal FND with adjuvant bevacizumab injection is effective at treating sectorial corneal vessels in children.

Chemical injury treated with autologous limbal epithelial stem cell transplantation and subconjunctival bevacizumab

Background

Limbal stem cell (LSC) deficiency leads to corneal opacity due to a conjunctivalization of the corneal surface. LSC transplantation, which can be followed by corneal keratoplasty, is an effective procedure to restore corneal transparency; however, a common cause of failure of this procedure is neovascularization (NV).

Methods

A 59-year-old man with a 21-year history of a corneal chemical burn caused by phosphoric acid in his left eye was examined. He presented with unilateral total LSC deficiency with severe conjunctivalization and a corrected distance visual acuity that was limited to hand motion.

Results

We reported the short-term in vivo efficacy of subconjunctival bevacizumab for progressive corneal NV in a patient with LSC deficiency that underwent LSC transplantation. Four months after autologous LSC transplantation and 1 month after the second subconjunctival bevacizumab injection, the patient’s corrected distance visual acuity was 1/10.

Conclusion

Subconjunctival injection of bevacizumab can reduce the corneal NV, reducing conjunctival inflammation and supporting restoration of a stable ocular surface that is able to counteract graft failure, with no toxicity for the transplanted LSC.

Treatment of Corneal Neovascularization Using Anti-VEGF Bevacizumab

Purpose. To evaluate antiangiogenic effect of local use of bevacizumab (anti-VEGF antibody) in patients with corneal neovascularization. Methods. Patients were divided into two groups. All patients suffered from some form of corneal neovascularization (NV). Patients in group A received 0.2–0.5 mL of bevacizumab solution subconjunctivally (concentration 25 mg/mL) in a single dose. Group A included 28 eyes from 27. Patients in group B applied bevacizumab eye drops twice daily (concentration 2.5 mg/mL) for two weeks. Group B included 38 eyes from 35 patients. We evaluated the number of corneal segments affected by NV, CDVA, and the incidence of complications and subjective complaints related to the treatment. The minimum follow-up period was six months. Results. By the 6-month follow-up, in group A the percentage reduction of the affected peripheral segments was 21.6% and of the central segments was 9.6%; in group B the percentage reduction of the central segments was 22.7% and of the central segments was 38.04%. In both groups we noticed a statistically significant reduction in the extent of NV. Conclusion. The use of bevacizumab seems to be an effective and safe method in the treatment of corneal neovascularization, either in the subconjunctival or topical application form.