Fathimath Jila Shameem

Introduction

Visual Snow Syndrome (VSS) is a neurological disorder of visual perception characterised by continuous, flickering dots resembling the noise of a detuned television, affecting the entire visual field (1,2). This “visual static” or “visual snow” is continuous, may be black-and-white or coloured, and can appear flashing or transparent (1–3). It is present under all lighting conditions, persists 24/7, and may continue even with the eyes closed (3).

The exact prevalence of VSS remains unknown(2–4). VSS most frequently affects individuals between 29 and 50 years of age, although the onset of symptoms has been reported from early childhood(3).

Pathophysiology

The exact cause of VSS remains unclear. However, it is believed to be a disorder of how the brain processes visual information rather than a structural eye disease (1,2). One hypothesis attribute it to cortical hyperexcitability, particularly in the visual cortex (5). A neuroimaging study demonstrated hypermetabolism in the lingual gyrus, a region of the brain’s visual cortex essential for functions such as visual memory and colour perception and implicated in conditions such as photophobia (2). Another hypothesis is thalamocortical dysrhythmia of the visual pathway, suggesting a disruption in the filtering and processing of sensory signals (2,6). 

Signs & Symptoms

The main clinical feature of VSS is visual snow. In addition, individuals experience other visual symptoms, including palinopsia (prolonged afterimages or trailing effects when objects move), photophobia (sensitivity to light), nyctalopia (impaired night vision) and entoptic phenomena (visual perceptions arising from within the eye, such as floaters, the blue-field entoptic phenomenon, self-lighting, and spontaneous photopsia) (2,3). Despite these symptoms, eye examination is normal. Although many of these symptoms can occur transiently in healthy individuals or in patients with ophthalmic diseases, their persistent and debilitating nature, despite a normal ophthalmic examination, distinguishes VSS from other visual disturbances (2).

Those with VSS may experience non-visual symptoms such as migraine, tinnitus and paraesthesia(4). Studies also showed that individuals with VSS frequently experience anxiety, impaired concentration, lethargy, and depression(2).

Diagnosis and Investigations

VSS is a clinical diagnosis based on characteristic symptoms and the exclusion of other causes, such as underlying ophthalmological and neurological diseases (2). Therefore, a detailed history and comprehensive ophthalmic and neurological examinations are essential to exclude other conditions that may cause visual disturbances. The International Classification of Headache Disorders (ICHD-3) diagnostic criteria for visual snow syndrome are shown in Table 1 (4).

In VSS, ophthalmological tests such as visual acuity, fundoscopy, and visual fields are typically normal (7). Additional tests, such as optical coherence tomography (OCT) and electroretinography, may be required to exclude retinal disease (3). Neuroimaging, such as computed tomography (CT) or magnetic resonance imaging (MRI), may be performed to exclude other neurological pathologies in patients with neurological symptoms (3). Other concerning features that should prompt further diagnostic evaluation include new-onset symptoms, older age, episodic or sudden worsening of symptoms, unilateral or hemifield visual snow, absence of associated visual symptoms, and a prior history of ophthalmic or neurological disease (4). 

A	Dynamic, continuous, tiny dots across the entire visual field, persisting for >3 months
B	Additional visual symptoms, with at least two of the following: • Palinopsia • Enhanced entoptic phenomena • Photophobia • Nyctalopia
C	Symptoms are not consistent with typical migraine visual aura
D	Symptoms are not better accounted for by another disorder

Differential Diagnosis

The differential diagnosis of VSS includes ophthalmic, neurological, and psychiatric conditions that may also cause visual disturbances(3). Some of the differential diagnoses for VSS and their distinguishing features are summarised in Table 2(3). Features that help distinguish VSS from other conditions include persistent bilateral symptoms involving the entire visual field, with normal ophthalmic and neurological examinations (4).

	Differentials	Key Distinguishing Features
Ophthalmic	Posterior Vitreous Detachment (PVD), retinal tear/detachment	Brief intermittent peripheral flashes; eye‑movement related; new floaters or visual field loss
	White dot syndromes, autoimmune/infectious retinopathies	Intermittent scintillations/shimmering lights, scotomas, reduced vision
	Rod–cone dystrophies (e.g. retinitis pigmentosa)	Progressive nyctalopia and visual field loss
Neurological	Migraine aura, occipital love visual seizures	Episodic, transient visual symptoms lasting <1 hour, seizures.
Psychiatric / drug-related	Hallucinogen-persisting perception disorder (HPPD), psychosis, drug intoxication	History of substance misuse, psychotropic drugs or psychiatric illness

Management

There is currently no definitive treatment for visual snow syndrome(2,4). Management focuses on patient education and reassurance, emphasising the benign nature of VSS while acknowledging the impact of symptoms on quality of life(3). Non-pharmacological strategies to alleviate patients’ symptoms include chromatically tinted lenses to reduce the perception of visual snow, palinopsia, and photophobia, as well as oculomotor-based therapy techniques aimed at reducing palinopsia(2).

Several medications, including benzodiazepines, lamotrigine, topiramate, and acetazolamide, have been trialled to treat VSS and have shown variable results, with partial improvement (2–4). Some studies suggest that lamotrigine and topiramate may offer the greatest potential benefit, particularly as they are also effective in managing coexisting migraine(3).

References

1. Stern JI, Robertson CE. Visual Snow: Updates and Narrative Review. Curr Pain Headache Rep. 2024 Feb 1;28(2):55–63.

2. Visual Snow Syndrome – Symptoms, Causes, Treatment | NORD [Internet]. [cited 2026 Jan 15]. Available from: https://rarediseases.org/rare-diseases/visual-snow-syndrome/

3. Visual Snow Syndrome: A Perplexing Storm of Misperception – American Academy of Ophthalmology [Internet]. [cited 2026 Jan 15]. Available from: https://www.aao.org/eyenet/article/visual-snow-neuro-ophthalmology

4. Rusztyn P, Stańska W, Torbus A, Maciejewicz P. Visual Snow: A Review on Pathophysiology and Treatment. J Clin Med [Internet]. 2023 Jun 1 [cited 2026 Jan 15];12(12):3868. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC10299246/