Lights in your peripheral vision, or eye floaters, are most often caused by changes in the jelly-like substance in the eyes due to age, explains the Mayo Clinic. They also might be caused by inflammation, bleeding in the eye or a torn retina.
When eye floaters occur due to age, it is often due to the jelly-like substance in the eye liquefying. This causes clumping which can block the light that comes through to the retina, according to the Mayo Clinic. Eye floaters may also be caused by inflammation or infection in the eye. In this case, the back of the eye is affected.
Eye floaters may also be caused by bleeding in the eye, as shown by the Mayo Clinic. This bleeding is caused by a number of things including trauma and blood vessel issues. Some people who tear their retina also see flashes of light. This is a very serious injury. If not treated, it can lead to permanent blindness. It is always a good idea to make an appointment with an eye doctor if seeing light flashes. Though it is likely a minor issue, like normal aging, it might turn out to be something much more serious like a torn retina.