Floaters are small, moving spots in your field of vision. They can look like little dots, threads, or cobwebs. They move when you try to look at them and are most noticeable in bright light or when you are looking at a light-colored background, such as a white wall or a blue, cloudless sky.
Flashes are flickers or streaks of light that usually happen around the edges of your vision. Closing your eyes does not make them go away. You may not be able to tell in which eye the flashes happened. They are usually more visible in the dark, such as at night.
What is the cause?
Most floaters and flashes are caused by changes in the gel-like fluid that fills the inside of your eye. Small floaters are usually caused by clumps of tissue that move or cast shadows inside the gel.
Large floaters may be caused by the gel shrinking and moving forward toward the middle of the eyeball. This is common after age 60.
Flashes may happen when the gel tugs or pulls on your retina. The retina is the lining at the back of your eye that senses light coming into your eye. If the gel tears the retina, it can lead to a retinal detachment. Retinal detachment is when the retina pulls away from the tissues underneath it. This can cause a permanent loss of vision.
What are the symptoms?
Almost everyone has some floaters and flashes, and they are usually harmless. However, floaters or flashes can be a symptom of a problem with your retina.
The warning signs of a retinal tear or detachment include:
Suddenly seeing many new flashes of light or many new floaters
Loss of side vision
Blurred or distorted vision
If you have these symptoms, call your healthcare provider right away.
How are they diagnosed?
Your eye care provider will ask about your symptoms and medical history and do exams and tests such as:
An exam using a microscope with a light attached, called a slit lamp, to look closely at the front and back of your eye
An exam using drops to enlarge, or dilate, your pupils and a light to look into the back of your eyes
An ultrasound, which uses sound waves to show pictures of the back of your eye
How are they treated?
Flashes and floaters not caused by a retinal tear or detachment are harmless and do not require treatment. They may never go away completely, but they tend to become much less noticeable with time. Most people learn to ignore them over time.
If the floaters or flashes are caused by a retinal tear or detachment, you may need laser treatment or surgery.
Adult Advisor 2015.1 published by RelayHealth. Last modified: 2013-02-13 Last reviewed: 2014-10-28
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
Eye Flashes and Floaters: References
American Academy of Ophthalmology. 2013-2014 Basic and Clinical Science Course. San Francisco: American Academy of Ophthalmology, 2013; v.1-13.
Miller NR, Newman NJ, Biousse V and Kerrison JB, eds. Walsh and Hoytâ€™s Clinical Neuro-Ophthalmology, 6th ed. Baltimore: Lippincott Williams & Wilkins, 2004;v.1-3.
Yanoff M and Duker JS. Ophthalmology, 3rd edition. Philadelphia: Mosby, 2008.