#HALLUCINATION SYNONYM SERIES#

Most of these can in fact be experienced by healthy individuals (especially in the case of floaters or retinal afterimages), or by patients with ophthalmological diseases the key difference with visual snow is that they manifest in a recurring, debilitating and pervasive manner and in the context of a perfectly functional optic apparatus. It is important for researchers and clinicians to distinguish visual snow from other phenomena and to recognize the associated symptoms (8). Up to 75% of individuals with visual snow report at least three of these four ancillary visual phenomena, which along with the static itself form the “visual snow syndrome” (3). Entoptic phenomena that are found (either alone or in combination) in visual snow, are the blue field entoptic phenomenon, floaters (the perception of which is defined as myodesopsia), self-light of the eye and spontaneous photopsia. The latter constitutes a group of symptoms considered to arise from the optic apparatus, which in the case of visual snow is completely intact and undamaged. In addition to the static, or snow, patients can experience additional visual symptoms of either direct neurological origin, such as palinopsia (either in the form of preserved images from stationary scenes or as visual trailing), photophobia and nyctalopia, or the entoptic phenomena. This ‘static’ is typically black and white but can also be colored, flashing or transparent. The main clinical feature of the syndrome described consistently by patients is an unremitting, positive visual phenomena, present in the entire visual field and characterized by uncountable tiny flickering dots interposed between the person’s vision and the background. Admixing these issues has delayed recognition of the syndrome. Lastly, many patients are told they simply are normal. Although it seems hallucinogens can trigger a similar disturbance (7), it is clear visual snow syndrome can be entirely independent of drug triggers. Visual snow has been considered to be the same condition as hallucinogen persisting perception disorder (HPPD) (6).

#HALLUCINATION SYNONYM SERIES#

Visual snow has been misdiagnosed in case series being mixed with persistent migraine aura, which has led to mechanistic confusion, diagnostic imprecision (4) and certainly the use of treatments that have not been useful (5).

The first literature reports of visual snow mostly represented isolated clinical descriptions in the context of larger groups of patients affected by persistent visual disturbance, previously defined as “persistent positive visual phenomena” (1). Since its first description (1), the introduction of the term visual snow (2) and its formal clinical definition less than five years ago (3), visual snow is now being recognized by physicians and scientists as a new entity in the neurological world. Visual snow is a chronic condition, sometimes highly disabling, uncommon condition that is in need of collaborative research and lateral thinking to make progress towards understanding, treatment and cure. Initial functional brain imaging research suggests visual snow is a brain disorder.

Research has been limited because of issues of case identification and diagnosis, the latter now largely addressed, and the limited size of any studied cohort. This early onset, combined with a general lack of recognition by health care providers, suggest it is an uncommon problem. The average age of the visual snow population seems to be younger than for many other neurological disorders. The prevalence of visual snow in the general population is currently unknown. In addition to the static, or “snow”, affected individuals can experience additional visual symptoms such as visual images that persist or recur after the image has been removed (palinopsia) sensitivity to light (photophobia) visual effects originating from within the eye itself (entoptic phenomena) and impaired night vision (nyctalopia). Visual snow is a neurological disorder characterized by a continuous visual disturbance that occupies the entire visual field and is described as tiny flickering dots that resemble the noise of a detuned analogue television. Stay Informed With NORD’s Email Newsletter.Find a Rare Disease Patient Organization.Find Clinical Trials & Research Studies.Launching Registries & Natural History Studies.A Podcast For The Rare Disease Community.

Hallucination synonym