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Closed-eye hallucinations and closed-eye visualizations (CEV) are hallucinations that occur when one's eyes are closed or when one is in a darkened room. They should not be confused with phosphenes , perceived light and shapes when pressure is applied to the eye's retina, or some other non-visual external cause stimulates the eye.
To see it, one must be in a dark room, with one eye closed; one must look straight ahead while moving a light back and forth in the field of the open eye. Then one should see the sixth Purkinje as a dimmer image moving in the opposite direction. The Purkinje tree is an image of the retinal blood vessels in one's own eye, first described by ...
Visual snow syndrome (VSS) is an uncommon neurological condition in which the primary symptom is that affected individuals see persistent flickering white, black, transparent, or colored dots across the whole visual field. [7] [4] Other common symptoms are palinopsia, enhanced entoptic phenomena, photophobia, and tension headaches.
Ramachandran suggests that James Thurber, who was blinded in one eye as a child, may have derived his extraordinary imagination from the syndrome. [25] Vikram Chandra's book Sacred Games (2006) David Eagleman's book Incognito: The Secret Lives of the Brain; Oliver Sacks' 2012 book Hallucinations
They may include fully formed images, such as human figures or scenes, angelic figures, or unformed phenomena, like flashes of light or geometric patterns. [ 2 ] [ 3 ] Visual hallucinations are not restricted to the transitional states of awakening or falling asleep and are a hallmark of various neurological and psychiatric conditions. [ 3 ]
Illusory palinopsia is often worse with high stimulus intensity and contrast ratio in a dark adapted state.Multiple types of illusory palinopsia often co-exist in a patient and occur with other diffuse, persistent illusory symptoms such as halos around objects, dysmetropsia (micropsia, macropsia, pelopsia, or teleopsia), Alice in Wonderland Syndrome, visual snow, and oscillopsia.
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Negative afterimages are generated in the retina but may be modified like other retinal signals by neural adaptation of the retinal ganglion cells that carry signals from the retina of the eye to the rest of the brain. [3] Normally, any image is moved over the retina by small eye movements known as microsaccades before much adaptation can occur ...