it just occurred to me that some of my salvia trips are almost isomorphic with the descriptions of visual migranes, or 'auras'...except it's not limited to one side of the visual field.

Quoted:
"Seeing multitudes of tiny, identical structures, sometimes “unrolling” steadily, sometimes flickering, forming and reforming, all over the visual field, is common in migraine auras, though it is only occasionally that these are elaborated into tiny skulls, or arrays of faces or animals or other objects."

EDIT: whoops, should've kept reading, the association with self-induced drug hallucinations is already brought up here.

..."Klüver spoke here of hallucinatory “form constants” and the tendency to “geometrization,” to the “geometrical-ornamental,” seemingly built into the brain-mind. The visions produced by mescal and other hallucinogens would usually progress from these elementary forms of hallucination to elaborate visions of a much more personal and sometimes mystical sort (including scenes of people, animals, and landscapes). But Klüver remarked that the lower-level, geometric hallucinations that preceded these were identical to those found in a variety of conditions: migraine, sensory deprivation, low blood sugar, fever, delirium, or the hypnopompic and hypnagogic states that come immediately before and after sleep. Indeed, even in the absence of any special medical conditions, they could be evoked in anyone by flickering lights, or sometimes even by simply applying pressure to the eyes."