Age related Macular Degeneration (AMD or ARMD) is most commonly classified as dry or wet form.
The dry form passes through early and intermediate stages before reaching the advanced stages. It is characterised by deposition of drusen, which happens due to wear and tear related to ageing and reflects by products of general metabolism of the eye. These deposits are clinical evidence of damage the retinal pigment epithelium (RPE) layer of the retina, whose primary function is to nourish the light sensing receptors in the retina. Significant damage to the RPE function results in symptoms over long term. Advanced forms of dry ARMD result in irreversible atrophy of the RPE as well as the light sensing regions of the retina (the photoreceptors).
The wet form of ARMD is characterised by presence of exudation or bleeding. It happens due to development of a leaking membrane that has abnormal vessels (called as choroidal neovascular membrane-CNVM) or its related forms. If untreated it leads to swelling of the macula (central retina) or bleeding inside it, causing moderate-severe vision loss. In its natural course, the membrane will turn into a scar causing irreversible and severe vision loss. Rarely there can be severe bleeding in the eye resulting in near total blindness.
Contributed by
Dr Brijesh Takkar
CRTP Fellow, IHOPE
Consultant Ophthalmologist, Vitreo Retinal Diseases
L V Prasad Eye Institute