Age Related Macular Degeneration affects only the central area of vision. It does not affect peripheral (side) vision and so does not cause complete loss of vision. In most cases, the condition is only ever mild.
The early stages have no noticeable effect on vision. Mild changes may delay the adaptation of vision to changes in ambient illumination. If more pronounced, there may be some distortion of size, shape and colour and objects can appear blurred and patchy. This causes greatest difficulty when looking at detail, such as when reading, looking at faces or driving. It is less of a problem whilst walking about, when peripheral vision is relied upon to a greater degree.
More advanced ARMD generally affects people much later in life and makes most visual tasks difficult. With severe ARMD, the central vision becomes a dark smudge and may drop to the level of partial sightedness or legal blindness. Macular degeneration is the leading cause of blindness in the western world.