Photocoagulation of subfoveal choroidal neovascular membranes in age related macular degeneration: the impact of the macular photocoagulation study in the United Kingdom and Republic of Ireland

Age related macular degeneration (AMD) is the leading cause of blind registration in the developed world.1 Choroidal neovascularisation (CNV) leading to haemorrhage and scar formation beneath the central retina accounts for the majority of cases of legal blindness in AMD (80% to 90%), the remainder being attributable to atrophic macular changes.2

A CNV membrane is described as subfoveal if any part of the lesion lies beneath the centre of the foveal avascular zone (FAZ). The concern regarding laser ablation of subfoveal lesions rests on the fact that photocoagulation of such a CNV membrane necessarily results in destruction of the overlying retina. In 1986, the Macular Photocoagulation Study (MPS) Group initiated a randomised clinical trial to evaluate laser ablation of subfoveal CNV membranes. The inclusion criteria were—a CNV membrane with a classic component and well defined borders; size of lesion ≤3.5 MPS disc areas; and a portion of the CNV membrane directly beneath the geometric centre of the FAZ.3 It was found that such patients who were treated according to the MPS protocol had significantly better visual acuity than untreated patients at 48 months’ follow up, but that treatment was associated with an immediate average reduction in acuity of …