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Many people, at some time in their lives, notice floaters
in one or both eyes. These are perceived as small spots
or strands that seem to drift in the field of vision, traveling
rapidly with eye movements and then floating slowly when
eye movements cease. Floaters are most readily seen
against a bright background such as well illuminated
reading material, a computer screen, or bright sky.
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Light flashes may occur in conjunction with floaters
or may occur separately. Unlike floaters, light flashes
(photopsias) are typically perceived in subdued lighting
or even total darkness. Photopsia can range from minimal
light twinkles to flashes that are bright enough to suggest
a neon sign or camera flash.
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Most occurrences of floaters or light flashes relate to
changes in the jelly-like substance called vitreous which
fills the entire back cavity of the eye. The vitreous is
transparent and has a solid consistency similar to gelatin.
As people grow older, the vitreous undergoes a normal
aging process, becoming more liquid and less jelly-like.
Often the partially liquefied vitreous will abruptly “collapse”
inside the eye causing a shower of floaters to appear. The
floaters are aggregates of protein which have formed in
the vitreous during the liquefaction process.
When the vitreous collapses, it begins to separate
from the retina. The mechanical pull of the vitreous
on the retina during this separation causes light flashes.
Sometimes during this separation process a retinal tear
develops and can lead to a retinal detachment. Often
when a retinal tear occurs, at least a small amount of
bleeding is present in the vitreous and may be noted
by the patient as a multitude of black dots or a hazy
decrease in vision.
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The sudden occurrence of floaters or flashes can be
an important warning signal of impending retinal problems.
A small percentage of people who develop the abrupt
onset of prominent floaters or light flashes in an eye will
be found to have a retinal tear on careful ophthalmoscopic
examination. Retinal tears can often be treated with laser
or freezing methods if a beginning retinal detachment is
not present.
Fortunately, the majority of people who experience floaters
or light flashes do not develop serious retinal problems.
In most instances, the floaters and flashes gradually
subside over a period of time with no permanent alteration
in vision. Since flashes and floaters can, however, be an
important warning of a retinal tear or impending retinal
detachment, their sudden appearance is of sufficient
concern to warrant careful evaluation by your
ophthalmologist.
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