Eye flashes or photopsia can be caused by many conditions. Although flashes are harmless, they might indicate some serious eye issue which needs to be addressed immediately. Medical attention should be taken when flashes cause loss of vision and also small spots seem to float from one side to the other, thereby hindering the vision.
Migraines and very severe recurrent form of headaches which last for few hours to many days can cause visual symptoms. The light flashes look like zigzag lines, geometric patterns and sparkles when they occur with a migraine. Flashes might affect one eye or both and occur in the peripheral area of the vision. Light flashes sometime also occur due to ophthalmic migraine, a migraine without a headache.
Posterior Vitreous Detachment
The jelly like substance or the vitreous fluid fill the center of the eye and also gives it shape, is attached to the retina. With age and over time there is shrinking of the vitreous and it begins to detach from the retina. This is known as posterior vitreous detachment. In this the vitreous tugs or pulls on the retina, while the retina gets detached and stimulates it thus causing flashes to occur.
There is no known treatment for posterior vitreous detachment, through regular monitoring of the eye through eye checkups are helpful. Symptoms of this are similar to those of retinal detachment (condition in which there is permanent vision loss).
Retinal Detachment or Tear
Retinal tear and detachment also cause light flashes in the eye. This needs to be treated promptly. In case of permanent vision loss there is detachment of retina at the back of the eye, especially if the detachment takes place over the macula which is the main focus of the vision on retina. When the retina detaches from the eye, it loses the main source of nutrients. As there are photosensitive cells in the retina which are responsible for vision, the results of retina tear are severe.
Retinal damage occurs after trauma or as a complication from diabetes or posterior vitreous detachment. Vitreous gel tends to seep under the retina from the small crevices and holes formed by the retinal thinning. This in turn raises the sections and disconnects it from the eye. This can be corrected by laser treatment, cryopexy or an eye surgery.
A trauma like a hard blow on the head can lead the person to experience flashes of light. Also some medications can lead to toxic levels, like Digitalis can cause flashes of light. The symptoms of eye flashes also occur with macular degeneration, which is an age-related disease and in this the vision reduces gradually.
In case you have a concern or query you can always consult an expert & get answers to your questions!