There are a handful of conditions that can cause flashings lights. They include:
- posterior vitreous separaction
- inflammatory conditions of the optic nerve or retina
The first two are the ones we most frequently encounter in our day to day clinics.
Posterior vitreous separation is a phenomen that occurs in most people sooner or later. It involved a spontaneous separation of the vitreous from the retina at the back of the eye (the vitreous is the gelatinous substance that occupies most of the volume of the eyeball). As the vitreous separated form the retina it can exter tractional forces on the retina that the brain interprets as flashes of light
Occasionally, during vitreous separation, the retina can get traumatised and can bleed or tear. A tear or break in the retina can often be contained by laser treatment to the retina. Sometimes a tear can lead to retinal detachment
which can be sight-threatening and which can require surgery.
Ocular migraine is a phenomenon in which patients can experience lightening streaks in the periphery of the vision. These are thought to be related to aberrations in blood flow in the retina, caused by temporary tightening of small blood vessels. While this causes headache in classical migraine, if it happens in the retina, the brain interprets these stimuli as flashes of light.
Posterior vitreous separation is unlikely to occur in both eyes at exactly the same time, while ocular migraine can certainly do so.
I you think your problem is in line with posterior vitreous separation, it would be worth having your retina examined by an ophthalmologist
to ensure there are no tears in the retina. It would also be worth seeking attention if you have any recent visual deterioration.
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