The retina is the thin layer that lines the inside of the eyeball and acts as the film that captures your vision and transmits it to the brain. No matter how you stimulate the retina (shine a light in the eye, push on the outside of the eye, or pull on the retina from within the eye) it only responds by “seeing light”. The inside cavity of the eye is filled with a clear jelly called the vitreous. As we get older, the vitreous tends to liquefy, and pull away from the retina. In doing so, this process temporarily places traction on the retina and thus you see a quick flash of light like a flash of a camera. This is most often noticed at night when it is dark out and the flash is seen in the periphery of your vision. After the vitreous pulls away from the retina, small bits of debris float inside the eye and cast a shadow onto the retina. Thus there is often the perception of a bug in front of your eye or a hair in front of the eye. This process is known as a vitreous detachment.
These “Flashes and Floaters” are typically transient. The flashes will last a few days to a couple of weeks, while the floaters never fully go away but do settle down. The major concern with a vitreous detachment is that this common and benign process can sometimes pull too hard on the retina and tear it, leading to a retinal detachment. A retinal detachment is a sight threatening process that typically progresses over several days and is most often associated with an area of distorted peripheral vision. This distortion progresses as more of the retina detaches.
Since vitreous detachments can sometimes lead to a retinal detachment, it is recommended that patients with flashes, floaters, and most importantly changes in their peripheral vision, be examined as soon as possible.