Seeing stars or ashes is a common eye-related issue, but it’s generally nothing serious. Sneezing generates a lot of pressure in your head, which can in turn put pressure on the retina—the light-sensitive layer of tissue inside your eyeball—or optic nerve. Either one can then send messages to your brain, and signals from the eye to the brain get interpreted as light, whether or not actual light is entering the eye (the rings or spots of light you see are called phosphenes). A similar effect can happen from standing up too quickly after lying down. In this case, your blood pressure may drop, and the brain can be briefly deprived of oxygen, affecting the environment in the eye or optic nerve (cue the shooting stars).
Visit your doctor or an eye specialist if you see ashes and sparks much more regularly or randomly. Lights or shimmering spots in your vision can be a migraine symptom. The sudden appearance of ashes, and possibly blurred vision, can also signal a retinal tear or detachment, which is an emergency and requires surgery (it can cause permanent vision loss if left untreated).
Health’s medical editor, Roshini Rajapaksa, MD, is assistant professor of medicine at the NYU School of Medicine.