Drugs which bind to VEGF receptors without causing activation, thus blocking the production of new blood vessels and enhanced vessel permeability by the vascular endothelial growth factor (VEGF). They are used in the treatment of some forms of cancer (administered intravenously), and injected intravitreally in the treatment of choroidal neovascularization, retinal venous occlusion, and macular oedema.
Examples: bevacizumab, pegaptanib sodium, ranibizumab.
Syn. angiogenesis inhibitors.
See age-related macular degeneration;
diabetic retinopathy;
VEGF.
A common, chronic degenerative condition found in a large percentage of elderly patients (and sometimes middle-aged ones) characterized by loss of central vision. There are two main forms of the condition:
non-neovascular (dry, atrophic) AMD, which is the most common, and
exudative (wet, neovascular) AMD in which the loss of vision is the most severe. The main features of
dry AMD are the presence in the macular region of small, yellowish-white spots (hard drusen) and large, poorly defined, coalescing soft drusen, focal hyperpigmentation of the retinal pigment epithelium (RPE) and at a later stage geographic atrophy of the RPE and depigmentation exposing choroidal vessels. Visual acuity becomes markedly reduced, there is metamorphopsia and the condition usually becomes bilateral over several years. The condition is managed essentially by the use of low vision aids.
Exudative AMD has a similar clinical picture initially but is followed by choroidal neovascularization (CNV), which gives rise to subretinal fluid, haemorrhages, exudation, RPE detachment and subretinal fibrosis in the macular region resulting in severe loss of central vision. If detected early (usually with an Amsler chart), treatment with laser photocoagulation will reduce the risk of further visual loss.
Photodynamic therapy (PDT) is another method of reducing the risk of visual loss. It allows selective destruction of the choroidal neovascularization with minimal damage to the overlying retinal tissue. It consists of injecting a photosensitizing agent (e.g. verteporfin) that is taken up by the abnormal vessels and when activated by a laser light of a given wavelength (e.g. 689 nm) it damages and shrivels up the vessels. Recent drug therapies, such as the anti-VEGF ranibizumab and bevacizumab, which are injected intravitreally at regular intervals and designed to stop the leakage and the growth of blood vessels, not only reduce loss of vision but improve visual acuity in a significant percentage of cases of wet AMD.
Syn. senile macular degeneration.
See fluorescein angiography;
disciform scar;
drusen;
macular dystrophy;
lipofuscin;
age-related maculopathy;
oxidative stress;
macular pigment;
Kollner's rule;
photostress test;
VEGF.