Flashing lights in the eyes after running may relate to a number of conditions that affect the eye, and some of these will be more serious than others. If you experience lights flashing in your eyes after running it may signal the onset of a migraine, or in the most extreme cases it may indicate that your retina has become detached. In all cases, flashing lights in the eyes after running require medical attention.
Runners who experience flashing lights in their eyes may be developing a migraine headache. Visual disturbances frequently occur with these types of headaches, and flashing lights in the eyes often portend the more commonly known symptoms of migraines such as pain and nausea. Although the exact cause of migraines is not well understood, runners are best served to make sure they stay well hydrated during their runs and record what they eat and drink before their runs. According to Peter J. Goadsby, M.D., Ph.D., migraines can be triggered by certain types of foods including caffeine, nitrates and monosodium glutamate.
According to the American Academy of Ophthalmology, runners who are nearsighted have a higher risk of developing a detached retina during their lifetime. In addition to flashing lights in the eyes after running, retinal detachment will incur a swift decrease in your vision and may include the appearance of a grey cloud or curtain moving across your field of vision. A detached retina is a medical emergency and requires immediate attention.
If you experience flashes of light in one or both of your eyes after running, it may also mean that you have developed ocular melanoma. Though rare, one of the main symptoms of this form of cancer is the presence of flashing lights in the eyes, according to the American Academy of Ophthalmology. Other symptoms include blurry vision, spots on the iris and vision loss. The pupil itself may also change shape. If any of these symptoms apply see your doctor immediately.
In many cases, runners may feel the urge to push through whatever physical symptoms they encounter to attain their training goals. However, if you see flashing lights in your eyes after a training run, resist the temptation to ignore these symptoms. Continuing to run without taking time to confer with your doctor or eye care specialist may lead to permanent loss of vision. Take a rest from running if you see flashes in your eyes and seek medical attention right away.