negative scotoma

Negative scotoma: an area of partial or total blindness which usually followed by a scintillating scotoma but may happen before it or may be surrounded by a scintillating scotoma.

A negative scotoma may be either be an absolute scotoma and may seem like a blank spot where the person can not see any light or a relative scotoma in which some light may be seen but less than normal, the scotoma may be blurry as if looking through thick plastic.

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.