Seeing Stars and Flashes of Light

Seeing Stars
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Do you see stars or flashes of light on occasion? It is not an uncommon complaint and most of the time you have nothing to worry about. However, if it occurs frequently, you should have your eyes examined just in case it is a sign of something serious.

Why Do I See Stars?

"Seeing stars" is a common visual complaint, but it is usually a normal and harmless occurrence. If you close your eyes and rub them, you will probably see spots and flashes of light.

These images you see are called "phosphenes," an entoptic phenomenon characterized by the experience of seeing light without having light actually enter the eye. Phosphenes are produced by pressure on the eye. This pressure is translated into various patterns by the optic nerve.

What Causes Stars to Pop Up in Your Vision?

  • Valsalva maneuver -  A Valsalva maneuver is the act of forcibly exhaling while keeping the mouth and nose closed. It creates pressure on the upper body and head. Generally, it is not a very healthy thing to do although the maneuver is used help regulate cardiac dysfunctions. Sometimes this pressure can cause you to see spots of light that also can occur after a sneeze or a hard cough. This can also be caused by straining too hard when lifting something too heavy or trying to have a bowel movement.
  • Postural or Orthostatic hypotension - Orthostatic hypotension is caused by a sudden drop in blood pressure. The body's reflex mechanisms that attempt to keep blood pressure and blood flow to the brain constant kick in and the heart is stimulated to increase output. Blood vessels in our body also change which affect blood pressure. These changes affect the brain and we see stars. This happens when we have been laying down for too long and stand up too quickly.
  • Ophthalmic migraines - Some migraines have a visual aura that people see which usually precede a headache. Some people never get a headache but just see the visual aura. The aura can be in the form of prismatic colors, flashes of light, and sometimes stars. They usually last about 20 minutes and then go away. If a headache follows the flashes, it is called a "migraine headache." If these flashes or lines of light occur without a headache, it is called an "ophthalmic migraine," or a migraine without a headache.
  • Posterior vitreous detachment - Posterior vitreous detachment (PVD) is a common condition usually caused by aging. The vitreous, which lies against the retina, is the jelly-like substance that fills the center of the eye. Made mostly of water, the vitreous fluid gives the eye its shape. As we get older, the composition of the vitreous changes, and becomes less firm. This change sometimes causes the vitreous to pull on the retina. If the force of the pulling becomes strong enough, the vitreous may actually separate from the retina. When this occurs, we see flashes of light or stars. Most of the time a PVD is annoying but harmless. However, about 5% of the time, a PVD can cause a retinal tear or detachment.

While usually harmless, frequent flashes of light can be a warning sign of something more serious. A comprehensive eye examination will be needed to determine the cause.


Kahawita S, Simon S, Gilhotra J. Flashes and floaters - a practical approach to assessment and managementAust Fam Physician. 2014 Apr;43(4):201-3.

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