There are a few conditions that can cause a person to see white flashes, including a retinal detachment, vitreous detachment and an ocular migraine. White flashes of light in a person's peripheral vision are symptoms of these three conditions.
The vitreous is a jelly-like fluid found in the interior of the eyes. Due mostly to aging, the vitreous can pull away from the retina, causing a vitreous detachment. In some cases, a vitreous detachment can lead to a macular hole or retinal detachment, according to the Mayo Clinic. Although a retinal detachment can be painless, symptoms of this condition are floaters, lightening streaks and a shadow that covers a region of the vision in the affected eye. A retinal detachment requires medical treatment because it can lead to vision loss.
Similarly, an ocular migraine can present the symptom of flashing lights, along with blind spots or blindness.