positive scotoma

Positive scotoma: an area of vision loss or blockage that may be seen as a dark or black spot or the blockage of vision may be what seem to be various shapes or lines that may change in in brightness i.e they may get darker and lighter so it seems like a flickering light.

In 1871 Förster defined the difference between negative and positive scotoma (blind spot); if vision of the scotoma region is a void, it is a negative scotoma, and if the scotoma is an area of darkness/lightness or composed of hallucinatory patterns, it is called a positive scotoma.