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.
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