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Most vision researchers believe that phosphenes result from the normal activity of the visual system after stimulation of one of its parts from some stimulus other than light. For example, Grüsser et al. showed that pressure on the eye results in activation of retinal ganglion cells in a similar way to activation by light. [ 23 ]
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.
Photopsias is defined as an effect on the vision that causes appearances of anomalies in the vision. Photopsias usually appear as: flickering lights; shimmering lights; floating shapes; moving dots; snow or static; Photopsias are not generally a condition on their own, but a symptom of another condition.
Photophobia is a medical symptom of abnormal intolerance to visual perception of light. [1] As a medical symptom, photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence of actual physical sensitivity of the eyes, [2] though the term is sometimes additionally applied to abnormal or irrational fear of light, such as ...
Eye flashing: characterised by bursts or streaks of light that appear in an individual's field of vision. As eye flashing may indicate impending retinal detachment, medical attention is required. [8] Eyelid twitching: where the eyelid muscles contract in an irregular or abnormal pattern. Such movements can cause irritation and fatigue to the ...
The main symptom is loss of vision, with colors appearing subtly washed out in the affected eye. A pale disc is characteristic of long-standing optic neuropathy. In many cases, only one eye is affected and a person may not be aware of the loss of color vision until the examiner asks them to cover the healthy eye.
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 ...
Flashes of light may also be present. [91] Inflammation of the optic nerve causes loss of vision most usually by the swelling and destruction of the myelin sheath covering the optic nerve. The blurred vision usually resolves within 10 weeks but individuals are often left with less vivid color vision, especially red, in the affected eye.