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Floaters and Flashes

Floaters and flashes, although occurring for similar reasons, have separate implications.  However, they both occur in the context of changes within the jelly (vitreous gel) in the back compartment of the eye.  


When eyes develop, the back 4/5ths of the eye form with a completely clear jelly material known as vitreous gel.  It is not too dissimilar in consistency to the uncooked egg albumin and in childhood it is perfectly clear and completely fills the back part of the eye.  It lies against the retina, but only very loosely is it adherent to it, frequently not at all.  For a variety of reasons with several different exacerbations, this jelly eventually becomes degenerate (starts to break apart) as a normal, natural, and healthy event.  In the process, it has a tendency to pull away from the retina and this usually occurs in a somewhat symptomatic and dramatic event known as posterior vitreous detachment.

For the majority of people, this is met by no more than the onset of a few large floaters.  This may occur anytime from adulthood, particularly in people who have myopia, through to advanced age.  The floaters that form are permanent and harmless, although they can be sometimes quite annoying, particularly if a thick floater, usually circle or part circle shape, lies near the centre vision.  

It is not the thickening in the jelly that is apparent as the floater, but rather the floater is a shadow formed on the retina as light passing into the eye passes by the vitreous debris in the eye.  It is for this reason that the floater is most apparent in bright light and against particularly a plain surface, and is not evident when the ambient light level is low.  When the gel is particularly adherent at certain points to the retina, the process of posterior vitreous detachment is met by the jelly pulling against the retina sending a pulse of light to our vision centre that we see as a flash.  This is an important symptom, as it indicates that the jelly is pulling against the retina, and it is the symptom of a flash of light that would normally alarm most people and should prompt an immediate attendance to an eye specialist for a detailed examination of the retina, usually with a dilated pupil.  If the onset of a pulse of light is met by the development of many dozens, if not hundreds, of small, sharp floaters, then this indicates that the retina has been torn, at least its outer layer, which may cause no harm, or potentially the deeper layer which is more serious.  It is not possible for the sufferer to distinguish, and the onset of flashes with floaters must prompt an attendance to specialist.

The flashes are short-lived and irregular and sometimes most evident with change in lighting, particularly in the dark.  These are very different to the flashes of light that occur in a migraine, which tend to persist for a minute or up to 10 minutes and usually in the young precede a headache, or in the elderly are well known to that person as a migraine event.  The lights of migraine aura tend to be in a curved pattern, often with a sawtooth pattern.  These do not originate from the eye and a general practitioner would be able to give advice if they occur on a regular basis.


If floaters occur in the absence of any other visual symptoms, an attendance to an optometrist would often suffice.  If floaters occur in the context of flashing lights (photopsia), this should prompt referral from general practitioner or optometrist to a specialist for detailed examination of the retina.  The specialist after examining the eye will determine whether a break in the retina has occurred and if so what measures are required to manage this.  Available measures include observation alone, laser, or under some circumstances when the break in the retina has allowed liquid to pass under the retina in a condition known as retinal detachment, attendance to a retinal surgeon for surgery.  

Sometimes the floater, even without the more serious complication of tear and detachment of the retina, can be so problematic and annoying to a patient that they would elect to have this removed.  The procedure used to  remove a floater is known as a vitrectomy and is performed by vitreoretinal specialists and performed in an accredited hospital or day surgery facility.  The risks of such procedure are not insignificant and will be explained to you by the appropriate specialist.  The most common complication of this surgery is the development soon after of a cataract, requiring cataract surgery usually within a few months of the vitrectomy, which can be quite a problem, particularly in the young who may not have worn glasses before, as such cataract surgery will require spectacle use thereafter.  

There are no tablets or drops available for the removal of the symptoms of vitreous floaters.

People who must be particularly wary of these symptoms and must attend as soon as possible to a specialist or Emergency Department are those people who have myopia, or people who have diabetes or previous significant eye trauma.

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