What is "palinopsia"

n. A visual disturbance that causes images to persist to some extent even after their corresponding stimulus has left.

Palinopsia (Greek: palin for "again" and opsia for "seeing") is a visual disturbance defined as the persistent recurrence of a visual image after the stimulus has been removed. Palinopsia is not a diagnosis, but a broad term that describes a heterogeneous group of pathological visual symptoms with a wide variety of etiologies. Visual perseveration is synonymous with palinopsia.

In 2014, Gersztenkorn and Lee comprehensively reviewed all cases of palinopsia in the literature and subdivided it into two clinically relevant groups: illusory palinopsia and hallucinatory palinopsia. Hallucinatory palinopsia, usually due to seizures or posterior cortical lesions, describes afterimages that are formed, long-lasting, and high resolution. Illusory palinopsia, usually due to migraines, head trauma, prescription drugs, or hallucinogen persisting perception disorder (HPPD), describes afterimages that are affected by ambient light and motion and are unformed, indistinct, or low resolution.