Table 3. Visual snow and visual snow syndrome: diagnostic criteria.

All capital-letter criteria must be met.*
A	Dynamic, unremitting tiny dots over the entire visual field for more than 3 months without interruption
B	Additional visual symptoms, at least 2 of the following 4 forms: 1. Palinopsia (illusion, mostly in the form of after-images) 2. Intensified entoptic phenomena (Scheerer phenomenon: light-colored dots, particularly when looking up into the sky) 3. Photophobia (light sensitivity) 4. Nyctalopia (night blindness)
C	The symptoms are not identical with those of a typical visual migraine aura
D	The symptoms are not better accounted for by another disease

* If all capital-letter criteria are met, visual snow syndrome is present.

Modified from the International Classification of Headache Disorders (ICHD-3) (27)