Palinopsia

How it works

Palinopsia means “seeing again”. It is the name for any image that continues or comes back after the thing you saw is no longer there¹. A normal afterimage is not palinopsia. Afterimages come from tired cells in the retina and usually show up in reversed colours³. Palinopsia comes from the brain, and its copies are usually in the original colours¹.

Doctors split it into two types¹.

Illusory palinopsia is short and depends on the conditions. Moving objects leave a trail of copies behind them, like a strobe photograph. A bright object leaves a short copy. How bright the object is, the background contrast, and movement all change how strong it is¹. It is common in people with visual snow⁴ and can come with migraine¹. Some drugs have also been reported to cause it¹.

Hallucinatory palinopsia is different. A complete, detailed image of something seen earlier reappears and may last a long time. It does not depend on light or contrast¹. This form is linked to damage or irritation in the visual parts of the brain, for example from a stroke, a tumour, or seizures, and it needs a medical work-up¹.

The mechanism for the illusory type is thought to be a visual system that is slightly too excitable. This changes how the brain handles light and movement¹.

How common it is

There is no figure for the general population. One clinic study found palinopsia in 19 of 200 people with migraine (9.5%)⁶. The nearest figures come from visual snow syndrome, where palinopsia forms part of the diagnosis². In a survey of 235 people with visual snow, trailing and afterimages were among eight extra symptoms reported by more than a third⁴. Visual snow syndrome itself was found in 2.2% of 1,015 UK adults matched to census data⁵. Combining those two numbers would still undercount, because palinopsia also follows migraine, some drugs, and head injury¹.

Is it a problem?

A faint afterimage after you look at a bright light is normal and harmless¹. There is no clear line between that and a mild form of palinopsia¹. If trails or copies are part of visual snow, they can get worse over time. This happened to more than half of the patients in one study⁴.

See a doctor if:

• full, detailed copies of objects or people return after you looked away,
• the symptom is new and comes with headache, weakness, or confusion.

Those patterns need an examination, because hallucinatory palinopsia can come from a brain lesion or seizures¹.