To understand the significance of flashing lights and floaters, and the associated risk of retinal tear or detachment, it is helpful to be familiar with the anatomy of the eye.  The outer wall of the eye, the sclera, is lined internally by several layers; the innermost layer is the retina.  

The retina is a sophisticated layer of neurosensory tissue that acquires images and transmits them to the brain via the optic nerve.  


The posterior chamber is defined by the retina (see red line above) and the back surface of the lens. This chamber is filled with a jelly like substance, the vitreous humor (see blue above).  The vitreous is normally clear and homogeneous and slightly condensed in its perimeter where it comes into contact with the retina.  Specific sites where the retina and vitreous are especially adherent include the optic nerve, macula, peripheral retina and blood vessels.


With age, trauma, inflammation and other events, the vitreous jelly liquefies, and may collpase or swirl more than it previously did.  The vitreous becomes less homogeneous and relatively condensed particles of vitreous may be seen 'floating' within the more liquified vitreous. In addition, as the jelly shrinks, the thickened portion may pull away from its attachment to the retina. This traction on the retina stimulates the retina's photoreceptors and results in unformed visual images. These may be interpreted as very brief 'flashes' of light.



Floaters alone are relatively inconsequential and quite common.


However, if a person sees the sudden onset of floaters, particularly a 'flood', 'waterfall' or 'plume' of floaters, this may represent bleeding into the vitreous cavity and urgent examination by an ophthalmologist is advisable.


Flashing lights represent pulling or traction on the retina. When the jelly pulls away from the retina, the retina perceives this stimulus as flashing lights. Typically, the flashing lights from this issue are very brief, but can be plentiful. Other conditions, like migaines may cause flashing lights, but these last longer and are more organized.



If the reina is pulled, it can tear, so flashing lights are a fairly important ymptom and require immediate attention.





In short:   everybody.  


Nobody has amnesty from the jelly liquefying and pulling away from the retina. However, some people are at a higher risk for subsequent tearing of the retina.  These include people with thinner retinas or who have sustained trauma to their eyes. Among the higher risk group are nearsighted (myopic) people, people who had prior ocular inflammation, patients who underweent eye surgery, people with

a family history of retinal disease or a history of retinal disease in the other eye.  Some medical conditions, like Marfan's disease, also predispose to retinal disease. There has also been anecdotal reprots of medications that may predispose to retinal tears.



A torn retina can be arrested with laser and prevented from progressing to a detached retina. While not all torn retinas necessarily become retinal detachments, those that are associated with symptoms have a higher likelihood of progressing to detachment.  Any time that a person sees flashing lights or floaters it is prudent to get his or her eyes examined by an ophthalmologist promptly.  


LASER PHOTOCOAGULATION applies a focused beam of light into the eye to create a stronger adhesion between the retina and the wall of the eye.  When a retina is torn, the tear may allow fluid (or jelly) that exists in the eye cavity to seep through it and to go between the retina and the wall of the eye.  This separates the retina from the eye wall (a RETINAL DETACHMENT) and tends to progress allowing more retina to detach. Laser fuses the margins of the torn retina so that no fluid can extaend past the border established by the laser: