Flashes and floaters
The small specks or “bugs” that many people see moving around in their field of vision are called floaters. They are frequently visible when looking at a uniform background, like a blank wall or blue sky. In Roman times, floaters were described as flying flies (“muscae volitantes”).Floaters are small clumps of opaque gel that form in the vitreous, the clear jelly-like substance that fills
the inside cavity of the eye. Although they appear to be in front of the eye, they are actually floating in the fluid inside the eye and are seen as shadows by the retina (the light-sensing inner layer of the eye).The appearance of floaters, whether in the form of dots, circles, lines or cobwebs may cause much concern, especially if they develop suddenly. However, they are seldom very important, representing the process of normal aging. The vitreous gel shrinks with time, pulls away from the retina and causes floaters. This is especially common in nearsighted people and after a cataract operation.
Are floaters ever serious?
As the vitreous gel contracts and pulls away, the retina may be torn, sometimes causing a small amount of bleeding which may appear as a group of new floaters. A tear like this could lead to retinal detachment, which is a serious threat to vision. Uncommonly, floaters result from inflammation inside the eye or from crystal – like deposits which form in the vitreous gel.
Without examination by an ophthalmologist, there is no way of determining whether floaters are harmless or potentially serious. Any sudden onset of new floaters or flashes of light, indicating gel pulling on the retina, should be evaluated by your ophthalmologist.
What can be done about floaters?
Floaters may sometimes interfere with clear vision, often when reading, and can be quite annoying. If a floater appears in your line of vision, the simplest thing to do is to move your eye around, which will cause the fluid to swirl and allow the floater to move out of the way. Looking up and down is usually more effective than horizontal movements. In cases where the symptoms remain annoying, treatment is possible with laser therapy and sometimes surgical removal of the gel.
What causes flashing lights?
The vitreous gel which fills the inside of the eye sometimes pulls or tugs on the retina. This causes a sensation of light flashing, though no real light is actually present.
During the process of vitreous contraction, light flashes may appear on and off for several weeks. This commonly happens as we grow older, and is usually not cause for alarm, but should be examined as mentioned before. On rare occasions, light flashes associated with a sudden shower of new floaters may occur. Blacking out of part of the visual field may even be seen, and in these cases urgent examination by your ophthalmologist is necessary to determine whether a retinal tear or detachment has occurred.
Flashes of light, which appear as jagged lines or “heatwaves” lasting 10 – 20 minutes and present in both eyes, are likely to be as a result of spasm of blood vessels in the brain. Migraine is a common form of this, but not always associated with headache. In this case it is referred to as ophthalmic migraine, or migraine without headache.
Should you have your eyes examined if you have floaters or flashes?
These symptoms are usually not serious. Especially if floaters have been present for a long time and in a familiar pattern, no concern is necessary. However, if flashes of light are followed by a sudden onset of floaters, or if blacking out of part of the visual field is noticed, you should be examined urgently. The examination will involve careful observation of the retina and vitreous gel with high magnification and illumination. It is important to select an ophthalmologist with a specific interest in retinal conditions, as they are much better equipped to detect subtle abnormalities than someone who only occasionally examines a retina.