Choroidal Neovascularisation and surgery

In patients over 50, choroidal neovascularisation (CNV) is most likely due to age-related macular degeneration (AMD). In other patients, causes include multifocal inner choroidopathy, pathological myopia, angioid streaks, optic nerve drusen, presumed ocular histoplasmosis syndrome and idiopathic causes. These membranes are thought to be more likely to grow in a plane between the retina and retinal pigment epithelium (RPE) and were termed Type II membranes by Gass. Therefore, when found adjacent to the optic nerve (peripapillary choroidal neovascularisation), they may be suitable for surgical removal without damaging the underlying RPE. Many of these patients do well with observation, however, and the precise indications for surgery remain to be defined. In AMD, there tend to be multiple breaks in Bruch’s membrane (which underlies the RPE) and vascular proliferation under and above the RPE (termed Type I membranes by Gass). Surgery would not be expected to preserve RPE and is not generally indicated for CNV secondary to AMD.