[Management of corneal neovascularization prior to corneal transplantation: Report of 112 cases]

INTRODUCTION

The avascular nature of the cornea results from a balance between angiogenic factors and anti-angiogenic factors. Under pathological conditions, this homeostasis can be disturbed, resulting in the onset of corneal neovascularization. The purpose of our study was to report our experience in the management of corneal neovascularization prior to keratoplasty.

MATERIALS AND METHODS

This is a prospective study of 112 patients with corneal neovascularization and candidates for possible corneal transplant.

RESULTS

The average age of patients was 38 years, ranging from 15 to 72 years. The etiologies of neovascularization were dominated by ocular trauma (26.8 %). In total, 48.33 % of patients had superficial neovascularization, 18.52 % moderately deep and 33.2 % deep neovascularization. All patients received topical corticosteroids, 29.4 % received subconjunctival injections of bevacizumab, and 22.32 % intrastromal bevacizumab injections. Clinical course was marked by a decrease in the percentage of corneal neovascularization compared to the total corneal surface area, from 45 % (between 16 and 82 %) to 28 % (between 0 and 69 %) at Day 120. There was no statistically significant improvement in visual acuity.

DISCUSSION

Corneal neovascularization is a major risk factor for graft rejection; its management is crucial prior to every keratoplasty.

CONCLUSION

Corneal neovascularization can lead to increased risk of graft rejection. Proper management increases the success rate of penetrating keratoplasty.

[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.

[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.

[Corneal neovascularization: epidemiological, physiopathological, and clinical features]

Corneal neovascularization is defined as the presence of vessels within the normally avascular corneal stroma. This physiopathological process is the consequence of local hyper-expression of pro-angiogenic factors in response to tissue damage. These new vessels (neovessels), initially immature and poorly developed, predispose the cornea to lipid exudation, inflammation, and scarring. Additionally, the influx of vascular cells into the stroma induces a loss of the cornea's immune privilege, resulting in a higher rate of graft rejection. In this literature review, we touch on epidemiological, physiopathological, and clinical aspects of corneal neovascularization, as well as secondary complications.