Neovascular glaucoma (NVG) is a severe form of secondary glaucoma characterised by the proliferation of fibrovascular tissue in the anterior chamber angle.(1) In older literature, the term is also known as rubeotic glaucoma, haemorrhagic glaucoma, thrombotic glaucoma, and congestive glaucoma. Neovascular glaucoma runs an aggressive clinical course and is potentially devastating, where delayed diagnosis or poor management can result in complete loss of vision.(1)
The most common predisposing factor is retinal ischemia, although other ocular and extraocular causes may lead to the development of neovascular glaucoma. Depending on the extent and duration of neovascularisation, the condition can present through either a secondary open-angle or secondary closed-angle mechanism. New vessels that occur in the anterior chamber angle have different features than normal ones. The walls of these vessels have increased permeability due to the absence of tight intercellular junctions, which are prone to vascular leakage and variable amounts of cellular inflammation.(2,3) Along with new vessels, fibrotic membranes are formatting, which destructs trabecular meshwork and causes anterior synechiae.(4)
Retinal ischemia is a cascade of events beginning with an inadequate oxygen supply to the retinal cells leading to the release of various angiogenic factors, including vascular endothelial growth factor (VEGF) and interleukin-6.(5) In two-thirds of all cases, proliferative diabetic retinopathy (PDR) or ischaemic central retinal vein occlusion (CRVO) are the main causes for retinal ischaemia. Risk factors for neovascular glaucoma are retinal ischemia, head and neck irradiation, systemic vascular conditions, ocular tumours, ocular inflammatory conditions, and intraocular surgery.