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Many variations occur, but scintillating scotoma usually begins as a spot of flickering light near or in the center of the visual field, which prevents vision within the scotoma area. It typically affects both eyes, as it is not a problem specific to one eye. [5] [6] The affected area flickers but is not dark. It then gradually expands outward ...
Photopsia is the presence of perceived flashes of light in the field of vision.. It is most commonly associated with: [4] posterior vitreous detachment; migraine aura (ocular migraine / retinal migraine)
Visual auras can be simple or complex. Simple visual symptoms can include static, flashing, or moving lights/shapes/colors caused mostly by abnormal activity in the primary visual cortex. Complex visual auras can include people, scenes, and objects which results from stimulation of the temporo-occipital junction and is lateralized to one hemifield.
Another way in which the shadows of blood vessels may be seen is by holding a bright light against the eyelid at the corner of the eye. The light penetrates the eye and casts a shadow on the blood vessels as described previously. The light must be jiggled to defeat adaptation.
Visual snow is a phenomenon where a person perceives visual disturbances, such as fine graininess or "static," in their field of vision. This can occur in low-light conditions, in the dark, or when the visual system amplifies light perception.
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.
Charman et al. (1971) asked whether the LF were the result of single cosmic-ray nuclei entering the eye and directly exciting the eyes of the astronauts, as opposed to the result of Cherenkov radiation within the retina. The researchers had observers view a neutron beam, composed of either 3 or 14 MeV monoenergetic neutrons, in several ...
Blepharospasm is often associated with dry eyes, but the causal mechanism is still not clear. [16] [8] Research in New York and Italy suggests that increased blinking (which may be triggered by dry eyes) leads to blepharospasm. [24] [25] A case control study in China found that blepharospasm aggravated dry eyes. [26]