Visual Snow Syndrome and Other "Strange Vision" Complaints: Palinopsia, Entoptic Phenomena, Aura and Charles Bonnet
Last updated: November 2026
Some patients describe things that are hard to fit into textbook diagnoses: static like an untuned television, trails behind moving objects, sparkles in a blue sky, or vivid pictures in a failing eye. Many of these have names and recognised mechanisms. Knowing them lets you examine carefully, reassure correctly and refer the few who need neurological work-up.
Visual snow syndrome
A brain-based disorder of visual processing, often starting in young adults and frequently associated with migraine and tinnitus. The eye examination is normal.
| Diagnostic criteria (ICHD-3 appendix) | |
|---|---|
| 1 | Dynamic, continuous, tiny dots across the entire visual field, lasting more than 3 months |
| 2 | At least two of: palinopsia (after-images or trails), enhanced entoptic phenomena, photophobia, impaired night vision |
| 3 | Not consistent with typical migraine visual aura |
| 4 | Not better explained by another disorder |
- Work-up: full eye examination including dilated fundus, visual fields; OCT if any doubt; consider ERG in selected cases to exclude retinal dystrophy; neuroimaging only if there are atypical features or neurological signs.
- Exclude: drug-related persisting perception (hallucinogens), retinal disease, optic neuropathy, occipital lesions.
- Management: explain the diagnosis (this alone helps), treat migraine and anxiety, tinted lenses for light sensitivity; medicines such as lamotrigine help some patients, with limited evidence.
Other unusual symptoms
| Symptom | What it is | Action |
|---|---|---|
| Blue field entoptic phenomenon | Tiny moving bright dots when looking at a bright blue sky: white blood cells in retinal capillaries | Reassure |
| Floaters and vitreous shadows | Vitreous opacities | Dilated examination if new or with flashes (see floaters) |
| Phosphenes on eye movement | Vitreous traction or optic neuritis (with pain) | Dilated examination; assess optic nerve |
| Migraine aura | Zigzag, shimmering spreading scotoma for 5–60 minutes, homonymous | Neurology if new after 50 or atypical |
| Palinopsia | Persistence or repetition of images after the object has gone | Usually benign (migraine, visual snow, medicines); rarely occipital lesion |
| Charles Bonnet syndrome | Vivid, formed images (faces, patterns, people) in people with significant vision loss, with insight preserved | Reassure; it is not mental illness; improve vision and lighting; low vision support |
| Moore's lightning streaks | Brief vertical flashes in the temporal field, often in older adults | Dilated examination to exclude tears |
| Alice in Wonderland syndrome | Distorted size or shape of objects or body | Usually migraine or infection (e.g. EBV) in children |
Refer urgently if unusual visual symptoms come with a field defect, reduced acuity, RAPD, disc swelling or pallor, new neurological symptoms, or sudden onset after 50.
Pearls
- Ask the patient to describe or draw what they see; the description often makes the diagnosis.
- Visual snow involves the whole field and both eyes, continuously, for months.
- Tell Charles Bonnet patients clearly that they are not becoming mentally ill.
Common mistakes
- Labelling visual snow as anxiety without a full examination.
- Missing a retinal tear in a patient with new flashes called "migraine".
- Not asking older low-vision patients about hallucinations.
Test yourself: flip cards
Quick quiz
Related: "Is My Headache From My Eyes?" Eye Causes of Headache, What Glasses Can and Cannot Fix, and Red Flags, Floaters, Neuro-Ophthalmology Notes: Topics and Syllabus, Low Vision Assessment Step by Step: History, Charts, Contrast, Magnification and Rehabilitation, Monocular Diplopia and Ghost Images: Causes, the Pinhole Test and How to Find the Source.
Key sources
- Headache Classification Committee of the International Headache Society. ICHD-3, appendix A1.4.6 Visual snow
- Puledda F, Schankin C, Goadsby PJ. Visual snow syndrome: a clinical and phenotypical description of 1,100 cases. Neurology. 2020;94:e564-e574
- Schadlu AP, Schadlu R, Shepherd JB. Charles Bonnet syndrome: a review. Curr Opin Ophthalmol. 2009;20:219-222
📘 Want more exam-ready material? See Most Commons in Ophthalmology on Kindle, or browse all my books.
Looking for an eye specialist in Ahmedabad? Eye Department at Sadbhaav or book a consultation with Dr. Dhaval Patel.