Animation of the progress of epiretinal membrane disease. The retina is the light_sensitive membrane that lines the back of the eyeball. In epiretinal membrane, a thin transparent layer grey forms over the surface of the retina. The growth of this layer causes deformation of the layers below it, leading to macular oedema. This is an abnormal accumulation of fluid black spaces in the macula of the retina. The macula is the region of the retina responsible for the sharp vision in the centre of the visual field. Distortion of the area leads to distortion of vision, which appears as a warping or magnification of images in the central visual field. The condition can be treated with surgery if it starts to impair vision enough to cause problems. The layers of the retina are labelled here, from the sensory layer of nerve cells and light_sensitive cells at the top, resting on the dark retinal pigment epithelium RPE, all supported by the choroid membrane, which supplies the retina with oxygen and nutrients.