Macular defects in the central field
Where localised visual defects affect the central parts of a person's vision, they are likely to be aware of the affected area. The video shows how this might appear; in this case as a darkened area which follows the point of focus. (For other people such defects might appear as one or more highly distorted zones, or as coloured opaque patches). Defects such as these are doubly irritating because they occlude exactly what it is you are attempting to focus on and new skills of focussing using the unaffected area around the macula need to be developed. This is called 'eccentric' viewing. Because of the poorer peripheral resolution power, magnification is needed.