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Eye Floaters

by Kathryn Colby, MD, PhD

Eye floaters are specks or strings that appear to move through a person's field of vision but do not correspond to external objects. Floaters are common.


Eye floaters result when something besides light from the environment stimulates the retina, which is the light-sensing structure at the back of the eye. This stimulation causes the retina to send a signal to the brain. The brain may interpret the signal as an apparent object floating in the field of vision (floater) or as a simple, sudden flash of light that can look like lightning, spots, or stars (photopsia). Photopsias can occur when the eyes are rubbed. The most common cause of eye floaters is

  • Shrinking of the jellylike substance that fills the eyeball (vitreous humor)

Between about age 50 to 75 years, the vitreous humor shrinks and tugs on the retina from time to time. These tugs stimulate the retina, giving the illusion of light or objects, seen as floaters. Such floaters (idiopathic vitreous floaters) are not harmful. Less often, the vitreous humor pulls completely away from the retina (vitreous detachment).

Less common but more serious causes include

  • Detachment of the retina

  • Tear in the retina

  • Detachment of the vitreous humor

  • Bleeding in the vitreous humor

  • Inflammation of the vitreous humor

Sometimes migraines cause vision symptoms (see Migraines). These vision symptoms may be white, jagged flashing lines that appear first in the middle of the field of vision and then spread across the entire field of vision (not single objects like floaters). They typically then resolve over about 20 minutes, disappearing first from the peripheral field of vision and last from the center of the field of vision. People may not have a headache with them. These symptoms are called ocular or visual migraine. People can also have similar symptoms or lose vision in part of an eye for about 10 to 60 minutes, often before a migraine headache begins (called migraine aura). In these cases, symptoms are caused by a phenomenon in the brain, not in the retina.

Tumors (for example, lymphoma) of the eye are rare causes of floaters. Foreign objects in the eye can cause floaters but usually cause other symptoms, such as vision loss (see Vision Loss, Sudden), eye pain (see Eye Pain), or eye redness (see Eye Redness), that are more troublesome than floaters.


Not every instance of eye floaters requires an immediate evaluation by a doctor. The following information can help people decide when a doctor's evaluation is needed and help them know what to expect during the evaluation.

Warning signs

In people with floaters, certain symptoms and characteristics are cause for concern. They include

  • Sudden increase in floaters

  • Repeated, often lightning-like flashes of light

  • Complete or partial loss of vision (often feeling like part of the vision is covered by a shade or curtain)

  • Recent eye surgery or eye injury

  • Eye pain

When to see a doctor

Although most often floaters are not serious, people who have warning signs should see an eye doctor as soon as possible. They may have a serious vitreous or retinal disorder, and waiting a few days, or sometimes even hours, may lead to a permanent loss of vision. People without warning signs who have begun to notice a few floaters should see a doctor when practical, although a delay of a few days or more is unlikely to be harmful. People who have had floaters for some time and have no other symptoms should have an eye examination at some point, but timing is not critical.

What the doctor does

Doctors first ask questions about the person's symptoms and medical history. Doctors then do a physical examination. What they find during the history and physical examination often suggests a cause of the floaters and the tests that may need to be done (see Some Causes and Features of Eye Floaters).

Doctors ask the person to describe the floaters and then ask

  • When the person noticed floaters

  • What characteristics the floaters have (for example, shapes, movement, or whether they recur)

  • Whether floaters occur in one or both eyes

  • Whether the person sees flashing lights or whether any part of vision is missing or seems covered by a curtain

  • Whether the person has had an eye injury or eye surgery

  • Whether other symptoms (such as blurred vision, eye redness, eye pain, or headaches) are present

  • Whether the person is nearsighted

  • Whether the person has disorders that may affect vision, such as diabetes or immune system disorders (for example, AIDS)

The eye examination is the most important part of the physical examination. Doctors check sharpness of vision, eye movements, and the pupil's response to light. They also check the eyes for redness and the visual field for areas of vision loss.

Ophthalmoscopy is the most important part of the eye examination. Doctors first use drops to dilate the pupils. Then they use an ophthalmoscope (a light with magnifying lenses that shines into the back of the eye—see Figure: What Is an Ophthalmoscope?) to examine the inside of the person's eyes, including as much of the retina as possible. If one of the serious causes of floaters seems possible, ophthalmoscopy is repeated by an ophthalmologist. An ophthalmologist is a medical doctor who specializes in the evaluation and treatment (surgical and nonsurgical) of eye disorders.

Pressure in the eye (intraocular pressure) is measured after a drop of anesthetic is put into the eye.

Doctors put a drop of fluorescein stain in the eye and then use a slit lamp (an instrument that enables a doctor to examine the eye under high magnification—see Figure: What Is a Slit Lamp?) to examine the entire eye.

Some Causes and Features of Eye Floaters


Common Features*


Eye disorders that are not worrisome

Vitreous contraction floaters (floaters due to shrinking of the jellylike substance that fills the back part of the eyeball, called the vitreous humor)

A few small, translucent clumps or strands that

  • Occasionally come into the field of vision

  • Move as the eye moves

  • May be more noticeable under certain lighting (such as bright sunlight)

  • May occur in both eyes, although not at the same time

No recent change in the number or type of floaters

No effect on vision

A doctor's examination

Eye disorders that are serious

Detachment of the retina

Simple, sudden flashes of light that can look like lightning, spots, or stars (photopsias), that occur repeatedly or continuously

Loss of vision that affects one area, usually what is seen out of the corners of the eye (peripheral vision)

Loss of vision that spreads across the field of vision like a curtain

Sometimes in people with risk factors for detachment of the retina (such as a recent eye injury, eye surgery, or severe nearsightedness)

Examination by an ophthalmologist

A tear in the retina


Sometimes symptoms only in the peripheral field of vision

Examination by an ophthalmologist

Detachment of the vitreous humor from the retina

An increase in floaters over a period of 1 week–3 months, usually in older people

Floaters that resemble cobwebs

One large floater that moves in and out of the field of vision

Photopsias that come and go

Examination by an ophthalmologist

Vitreous hemorrhage (bleeding into the vitreous humor)

In people who have risk factors for this disorder (such as diabetes, a tear in the retina, sickle cell disease, or an eye injury)

Usually loss of the entire field of vision (not in just one or more spots)

Examination by an ophthalmologist

Sometimes ultrasonography of the retina

Inflammation of the vitreous humor (as may occur when Toxoplasma parasites, fungi, or rarely cytomegalovirus infect the eye )


Loss of vision affecting the entire field of vision

Possibly affecting both eyes

In people with risk factors for these infections (such as AIDS and other conditions that weaken the immune system)

Sometimes testing to detect microorganisms suspected of causing infection

Disorders not related to the eyes

Ocular migraine (migraines that cause vision symptoms)

Jagged lines that appear first in the center of the field of vision, then spread outward, and disappear after about 20 minutes

Sometimes blurring of central vision

Sometimes a headache after the disturbances in vision

Sometimes in people known to have migraines

A doctor's examination

Migraine aura

A blind spot, sometimes with shimmering spots and that lasts usually 10 to 60 minutes

Usually a headache after the disturbances in vision

Usually in people known to have migraines

A doctor's examination

*Features include symptoms and the results of the doctor's examination. Features mentioned are typical but not always present. Features occur in only one eye unless otherwise specified.


Doctors can often identify less serious causes during an examination, but if a serious disorder seems possible, doctors refer people to an ophthalmologist to make a diagnosis. Ophthalmologists are medical doctors who specialize in the evaluation and treatment (surgical and nonsurgical) of eye disorders. The ophthalmologist does more detailed ophthalmoscopy and may order testing. For example, for vitreous inflammation due to infection, testing to identify organisms suspected of causing infection may be needed.


  • For vitreous contraction floaters, no treatment

  • Sometimes vitrectomy

  • Treatment of other causes

Vitreous contraction floaters require no treatment.

Sometimes if a person has many floaters that interfere with vision, doctors may use a hollow needle to remove the vitreous humor from the eye and replace it with salt water. This surgical procedure is called vitrectomy. However, many doctors think vitrectomy should not be done for floaters because the procedure may cause detachment of the retina or cataracts and because sometimes floaters remain afterward.

Other disorders causing symptoms are treated. For example, surgery is done to repair a detached retina. Antimicrobial drugs are used for infections causing vitreous inflammation.

Key Points

  • People who have floaters but no warning signs rarely have a serious disorder.

  • People with floaters and warning signs may need to be referred to an ophthalmologist.

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