Angiogenesis in glaucoma filtration surgery and neovascular glaucoma: A review

Abstract

Angiogenesis may pose a clinical challenge in glaucoma, for example during the wound healing phase after glaucoma filtration surgery and in a severe form of secondary glaucoma called neovascular glaucoma (NVG). Up regulation of vascular endothelial growth factor (VEGF), a key mediator of angiogenesis, occurs in eyes that have undergone glaucoma filtration surgery, as well as those with NVG. This has led to studies investigating the ability of anti-VEGF therapy to improve outcomes, and we examine their findings with respect to the safety and efficacy of anti-VEGF agents, mainly bevacizumab and ranibizumab, in eyes that have undergone glaucoma filtration surgery or have NVG. Combining conventional therapies—such as anti-metabolites after filtration surgery and panretinal photocoagulation in NVG—and anti-VEGF drugs may achieve a synergetic effect, although further studies are required to evaluate the long-term efficacy of combination treatments.

The era of anti-vascular endothelial growth factor (VEGF) drugs in ophthalmology, VEGF and anti-VEGF therapy

“…As is well documented, hypoxia is an generative factor in many ocular diseases such as ocular ischaemic syndrome, proliferative retinopathies, and neovascular glaucoma. Hypoxia promotes VEGF transcription, so it upregulates angiogenesis to restore oxygen and nutrition supply for tissues [9]. However, VEGF not only plays the role in the angiogenesis and vascular barrier breakdown; it was shown that VEGF enhances leukocyte adhesion to vascular walls and increases expression of vascular cell adhesion molecule-1 (ICAM-1) in the retina and the brain [7].…”

Pathophysiology and management of glaucoma associated with phakomatoses

“…Few small studies have shown that intravitreal anti‐VEGF agents may lead to rapid regression of anterior chamber neovascularization due to all causes with a corresponding short‐term decrease in IOP (Aref, ; Kim et al, ; Vasudev, Blair, Galasso, Kapur, & Vajaranant, ). However, long‐term IOP reduction with anti‐VEGF agents has not yet been proven.…”

Current management of glaucoma and vascular occlusive disease

“…The current gold standard for treatment of NVG involves the administration of panretinal photocoagulation in order to decrease retinal oxygen demand and the associated ischemic drive for transcription of angiogenic factors [4]. Panretinal photocoagulation requires adequate view of the retina, which may not be possible in patients suffering from NVG due to coexistent corneal edema, lenticular opacity and/or vitreous hemorrhage.…”

“…Another option involves the intraocular administration of anti-VEGF antibodies in order to directly block the effect of newly formed angiogenic factors. Prior retrospective studies have shown that intravitreal injection of these agents leads to rapid regression of anterior chamber neovascularization with a corresponding short-term decrease in IOP [4]. However, the most commonly used anti-VEGF agents, bevacizumab and ranibizumab, have limited binding affinity to all VEGF isoforms and therefore may not offer a long-term solution to the condition.…”

“…Anti-VEGF injection therapy is often combined with panretinal photocoagulation in order to achieve this goal [4]. In patients suffering from NVG related to ocular ischemic syndrome, reversal of underlying source of ischemia may be warranted.…”