What is happening when my vision randomly flashes on occasion?

?retinal tear: The most common cause of "eye flashes" occurs when the gel in your eye separates (posterior vitreous detachment). In some circumstances separation of the gel can pull on the retina and cause a tear of the retina which can lead to retinal detachment and the need for emergency surgery. Floaters or black spots usually accompanies this. Other causes include migraine and inflammation of the eye.

See eye MD NOW: Intermittent flashes of light usually represent the vitreous tugging on the retina, but may indicate an impending retinal detachment. You should see an eye md soon.

Floaters: Sounds as if you have had a posterior vitreous detachment. This is a situation where the vitreous(jelly) of the eye detaches (not a retinal detachment), it then "crumples" up leaving dots, spots, strands of blurry vitreous; i.e. The "floater". When it pills away, it causes flashes. You should have an exam to ensure the incident did not tear the retina, which could lead to a retinal detachment.