Search results
Results From The WOW.Com Content Network
Flicker vertigo, sometimes called the Bucha effect, is "an imbalance in brain-cell activity caused by exposure to low-frequency flickering (or flashing) of a relatively bright light." [ 1 ] It is a disorientation -, vertigo -, and nausea -inducing effect of a strobe light flashing at 1 Hz to 20 Hz, approximately the frequency of human brainwaves .
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) migraine aura without headache; scintillating scotoma; retinal break or detachment; occipital lobe infarction (similar to occipital stroke)
If any of these serious disorders are present, the individual will usually have additional symptoms such as chest pain, a feeling of a racing heart, loss of speech or a change in vision. Many people, especially as they age, experience lightheadedness if they arise too quickly from a lying or seated position.
This can occur in low-light conditions, in the dark, or when the visual system amplifies light perception. In these cases, visual snow is a normal reaction of the body, related to the way photoreceptors (rods) and neurons respond to weak or insufficient stimuli. [citation needed]
Photic retinopathy is damage to the eye's retina, particularly the macula, from prolonged exposure to solar radiation or other bright light, e.g., lasers or arc welders.The term includes solar, laser, and welder's retinopathy and is synonymous with retinal phototoxicity. [1]
Symptoms typically appear gradually over 5 to 20 minutes and generally last less than 60 minutes, leading to the headache in classic migraine with aura, or resolving without consequence in acephalgic migraine. [3] For many sufferers, scintillating scotoma is first experienced as a prodrome to migraine, then without migraine later in life ...
As the light is being moved from one eye to another, both eyes begin to dilate, but constrict again when light has reached the other eye. If there is an efferent defect in the left eye, the left pupil will remain dilated regardless of where the light is shining, while the right pupil will respond normally.
Photokeratitis can be prevented by using sunglasses or eye protection that transmits 5–10% of visible light and absorbs almost all UV rays. Additionally, these glasses should have large lenses and side shields to avoid incidental light exposure. Sunglasses should always be worn, even when the sky is overcast, as UV rays can pass through ...