Visual snow is a transitory or persisting visual symptom where people see snow or television-like static in parts or the whole of their visual fields, especially against dark backgrounds. There are different causes for visual snow, i.e. visual snow is non-specific. Therefore, each subject with a leading complaint of visual snow needs a full diagnostic work-up including ophthalmic, neurological and psychiatric examinations as well as an MRI scan of the brain. For other uses, see Snow (disambiguation). ... Video noise In video and television, noise refers to the random dot pattern that is superimposed on the picture as a result of electronic noise, the snow that is seen with poor (analog) television reception or on VHS tapes. ... The term visual field is sometimes used as a synonym to field of view, though they do not designate the same thing. ... This article is about the branch of medicine. ... Neurology is a branch of medicine dealing with disorders of the nervous system. ... An MRI scan of a human brain and head. ... The mri are a fictional alien species in the Faded Sun Trilogy of C.J. Cherryh. ...

Causes

Visual Snow and other disturbances

Visual snow can occur in a variety of ophthalmic disorders that can be diagnosed by the presence of additional clinical signs and symptoms. Persisting visual snow can feature as a leading symptom of a migraine complication called persistent aura without infarction ^[1], commonly referred to as persistent migraine aura (PMA). It is important to keep in mind that there exist many clinical sub-forms of migraine where headache may be absent and where the migraine aura may not take the typical form of the zigzagged fortification spectrum, but manifests with a large variety of focal neurological symptoms. Image File history File links Download high-resolution version (986x974, 420 KB) Picture was made by Papanugue Background shows a street in Denmark There is another version of this image with the illustration of the in the article described negative after-images I, the creator of this work, hereby release... Image File history File links Download high-resolution version (986x974, 420 KB) Picture was made by Papanugue Background shows a street in Denmark There is another version of this image with the illustration of the in the article described negative after-images I, the creator of this work, hereby release...

Another possible cause of visual snow is hallucinogen persisting perception disorder (HPPD) following use of LSD, MDMA, psilocybin or other hallucinogens. In HPPD, the symptom of visual snow has been described ^[2] as aeropsia (literally "seeing the air"). It is noteworthy that HPPD can occur after a single dose of a hallucinogen and with a considerable latency between last drug intake and onset of persistent perception disorder, so taking a thorough life-time drug history is mandatory in the diagnostic work-up of visual snow. Hallucinogen Persisting Perception Disorder or HPPD is a disorder characterized by a continual presence of visual disturbances that are reminiscent of those generated by the ingestion of hallucinogenic substances. ... Lysergic acid diethylamide, commonly called LSD, LSD-25, or acid. ... ecstasy and religious ecstasy MDMA, most commonly known today by the street name ecstasy, is a synthetic entactogen of the phenethylamine family whose primary effect is to stimulate the brain to rapidly secrete large amounts of serotonin, causing a general sense of openness, empathy, energy, euphoria, and well-being. ... Psilocybin (also known as psilocybine) is a psychedelic alkaloid of the tryptamine family, found in psilocybin mushrooms. ...

Another condition that sometimes produces visual snow is optic neuritis (inflammation of the optic nerve), caused by multiple sclerosis (MS). Moreover, a variety of illnesses (e.g. Lyme disease, auto-immune disease) or nocious events (e.g. prolonged use of a VDU, dehydration, over-acidification) have been blamed by sufferers in self-help internet forums as causes of persisting visual snow, but none of these claims have been supported by evidence-based medicine. Some patients fail to find any apparent causative illness or event in their lives, instead saying the snow came out of nowhere or has been with them for their whole life. Optic neuritis, sometimes called retrobulbar neuritis, is the inflammation of the optic nerve that may cause a complete or partial loss of vision. ... An abscess on the skin, showing the redness and swelling characteristic of inflammation. ... This article is about the anatomical structure. ... Lyme disease, or borreliosis, is an emerging infectious disease caused by at least three species of bacteria from the genus Borrelia. ... Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. ... Nineteen inch (48 cm) CRT computer monitor A computer display, monitor or screen is a computer peripheral device capable of showing still or moving images generated by a computer and processed by a graphics card. ... Dehydration (hypohydration) is the removal of water (hydro in ancient Greek) from an object. ...

Related symptoms

In addition to visual snow, patients suffering from persistent perception disorder frequently have other types of visual disturbances such as starbursts, increased afterimages, floaters, trails, and many others ^[3]. Non-visual symptoms such as tinnitus or depersonalisation-derealisation are also frequently encountered. Secondary psychiatric sequelae such as anxiety, panic attacks or depression may develop and necessitate appropriate treatment. Palinopsia (Greek: palin for again and opsia for seeing) is a visual disturbance that causes images to persist to some extent even after their corresponding stimulus has left. ... For other uses, see Floater (disambiguation). ... Tinnitus (pronounced or ,[1] from the Latin word for ringing[2]) is the perception of sound in the human ear in the absence of corresponding external sound(s). ... In psychiatry, depersonalization (or derealization) is the experience of feelings of loss of a sense of reality. ...

Treatments

There currently is no established treatment for visual snow. In HPPD, clonazepam has been recommended as medication of first choice in patients seeking medical help ^[4]. Furthermore, drug abstinence is sometimes said to be of major therapeutic importance in HPPD. In persistent aura without infarction, the evidence so far suggests that acetazolamide may be the premier drug for patients with the repetitive form of aura status ^[5] and that valproate ^[6], lamotrigine ^[7], or topiramate ^[8] should be first choices for patients with the continuous form. When these oral drugs are ineffective, an intravenous injection or injections of furosemide should be tried ^[9]. However, with very little scientific research on the condition taking place, for the time being the effectiveness of such treatments remains based solely on anecdotal evidence. Beyond pharmacological approaches, appropriate counselling and cognitive behavioral interventions that focus on coping with the condition may be of huge importance. Clonazepam (marketed by Roche under the trade-names Klonopin in the United States and Rivotril or Rivatril in Europe, South America, Canada, India, and Australia) is a drug which is a benzodiazepine derivative. ... Acetazolamide, sold under the trade name Diamox®, is a carbonic anhydrase inhibitor that is used to treat glaucoma, epileptic seizures, benign intracranial hypertension and altitude sickness. ... Valproic acid or 2-Propylpentanoic acid is CH3CH2CH2CH(CH2CH2CH3)COOH . ... Lamotrigine (marketed as Lamictal (IPA: ) by GlaxoSmithKline, called Lamictin in South Africa, (Lamogine)[1] in Israel, and in South Korea) is an anticonvulsant drug used in the treatment of epilepsy and bipolar disorder. ... Topiramate (brand name Topamax) is an anticonvulsant drug produced by Ortho-McNeil Neurologics, a division of Johnson & Johnson. ...

See also

• Eye
• Hallucinations
• Migraine
• Vision
• Asthenopia
• Ectopia lentis
• Shot noise

For other uses, see Eye (disambiguation). ... A hallucination is a false sensory perception in the absence of an external stimulus, as distinct from an illusion, which is a misperception of an external stimulus. ... In psychology, visual perception is the ability to interpret information from visible light reaching the eyes. ... ... Anterior lens luxation Ectopia lentis is a displacement or malposition of the eyes crystalline lens from its normal location. ... Photon noise simulation. ...

References

External links

• Internet Resources For Visual Snow Patients
• Persistent aura without infarction