Common Light Flashes
The most common cause of light flashes (photopsia) is due to vitreous degeneration, a benign condition that occurs over time, but is accelerated in patients who are myopic or have sustained eye trauma. There are several other less common conditions which are associated with early vitreous degeneration.
Light flashes due to vitreous degeneration are characteristically seen in the far peripheral visual field and last less than a second and may be repetitive, but not continuous. They are arcuate in configuration, and they are often associated with either head or eye movement. Because of their low intensity they are observed only in the dark or subdued lighting. (see Floaters and Light Flashes) These symptoms need to be evaluated by an eye doctor, often a retina specialist.
Another type “light flashes” are those associated with ocular migraine. These “light flashes” are called “scintillating scotomas”, and are persistent, lasting 20 -40 minutes. Classically they are jagged, in a ring-like figure, begin centrally and expand outwardly. They are not associated with a headache, but can be visually troublesome until they resolve. Often these ocular migraines are not associated with any systemic problem, but if they start to get worse it is a good idea to see a neuro-ophthalmologist.
Less Common Causes of Light Flashes
Occasionally, patients with Age-related Macular Degeneration (AMD) will also complain of “light flashes”. These occur centrally and are described as “sparkling”. Invariably, these patients have advanced AMD, and the source of “sparkling” occurs due to extraneous stimulation of the damaged retina. In some patients this extraneous stimulation of the damaged retina does more than cause “sparkling”, it can cause the perception of well formed hallucinations, described as “trees, flowers, buildings, people, etc”. This condition has been well described and is called Charles-Bonet Syndrome.
If you start to suddenly notice any new flashes of light it is a good idea to contact your eye doctor for further evaluation.