Floaters and Flashes
What are floaters?
Floaters are caused by cellular debris that get trapped in the gel behind the eye. Since the eye is a closed system the debris has no where to go and can cause symptoms. When the light coming through eye hits the debris it can cast a shadow on the underlying retina. These shadows can look like cobwebs, flys or bugs floating in one’s visual field.
This detailed and informative introduction to the retina covers all the basics: anatomy, diabetic retinopathy, retinal detachments, and macular degeneration.
What causes floaters?
A very common cause of floaters is “posterior vitreous detachment”. In this condition the gel behind the eye contracts upon itself and causes a clump that can float directly in the visual axis. This is a fairly common occurrence especially with very near-sighted people.
Are floaters ever serious?
Even though floaters are relatively harmless most of the time, it is important to let your doctor know whenever you see new floaters. The reason for this is that occasionally a floater can be associated with a retinal hole, tear or detachment. Also, a large amount of new floaters may represent bleeding in the eye rather than just clumping of debris. Retinal problems are sometimes accompanied by flashing lights, a diffuse shower of new floaters or loss of side or central vision. If you have any of these symptoms you should contact your ophthalmologist immediately.
What can be done about floaters?
Floaters can sometimes get in the way of clear vision, which may interfere with your near or distance vision. Although this can be quite annoying it tends to improve over time. This may be because the floaters tend to dissolve or even to simply move out of the visual axis. In some cases, they cease to be annoying simply because one has gotten used to them. In rare instances we are able to eliminate floaters by performing a laser treatment to break them apart.
What causes flashing lights?
When the vitreous gel behind the eye pulls on the retinal tissue it can sometimes cause flashing lights. This can resemble sudden sparkles of light or even lightning streaks. Flashes can recurr for days, weeks or months and can sometimes indicate continued traction on the retina. You should contact your ophthalmologist immediately for these sympoms. Flashing lights are often the precursors of retinal holes, tears or detachments.
Some people experience flashes of light that appear as jagged lines or “heat waves” in both eyes, often lasting 10-20 minutes. These types of flashes are not caused by traction on the retina but by a spasm of blood vessels in the back part of the migraine ie: an ocular migraine. They are usually not accompanied by a headache and tend to be harmless. However, since it is often difficult for the patient to differentiate between a harmless ocular migraine and a retinal problem, it is advisable to contact your ophthalmologist should this occur.