Floaters are deposits of various size, shape, consistency, refractive index
Refractive index
In optics the refractive index or index of refraction of a substance or medium is a measure of the speed of light in that medium. It is expressed as a ratio of the speed of light in vacuum relative to that in the considered medium....

, and motility
Motility is a biological term which refers to the ability to move spontaneously and actively, consuming energy in the process. Most animals are motile but the term applies to single-celled and simple multicellular organisms, as well as to some mechanisms of fluid flow in multicellular organs, in...

 within the eye
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...

's vitreous humour
Vitreous humour
The vitreous humour or vitreous humor is the clear gel that fills the space between the lens and the retina of the eyeball of humans and other vertebrates...

, which is normally transparent. At young age the vitreous is perfectly transparent, but during life imperfections gradually develop. The common type of floater, which is present in most people's eyes, is due to degenerative changes of the vitreous humour. The perception
Visual perception
Visual perception is the ability to interpret information and surroundings from the effects of visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision...

 of floaters is known as myodesopsia, or less commonly as myiodeopsia, myiodesopsia, or myodeopsia. They are also called Muscae volitantes (from the Latin, meaning 'flying flies'), or mouches volantes (from the French). Floaters are visible because of the shadows they cast on the retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...

 or their refraction of the light that passes through them, and can appear alone or together with several others in one's field of vision
Visual field
The term visual field is sometimes used as a synonym to field of view, though they do not designate the same thing. The visual field is the "spatial array of visual sensations available to observation in introspectionist psychological experiments", while 'field of view' "refers to the physical...

. They may appear as spots, threads, or fragments of cobwebs, which float slowly before the observer's eyes. Since these objects exist within the eye itself, they are not optical illusions but are entoptic phenomena
Entoptic phenomenon
Entoptic phenomena are visual effects whose source is within the eye itself. In Helmholtz's words:...



Floaters are suspended in the vitreous humour
Vitreous humour
The vitreous humour or vitreous humor is the clear gel that fills the space between the lens and the retina of the eyeball of humans and other vertebrates...

, the thick fluid or gel that fills the eye. Thus, they generally follow the rapid motions of the eye, while drifting slowly within the fluid. When they are first noticed, the natural reaction is to attempt to look directly at them. However, attempting to shift one's gaze toward them can be difficult since floaters follow the motion of the eye, remaining to the side of the direction of gaze. Floaters are, in fact, visible only because they do not remain perfectly fixed within the eye. Although the blood vessels of the eye also obstruct light, they are invisible under normal circumstances because they are fixed in location relative to the retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...

, and the brain "tunes out" stabilized images
Stabilized images
Stabilized Images are images on the retina that are unaffected by microsaccade or ocular microtremor . Experiments by Riggs and Ratliff ) established the remarkable finding that stabilized images result in the fading and disappearance of the visual percept...

 due to neural adaptation
Neural adaptation
Neural adaptation or sensory adaptation is a change over time in the responsiveness of the sensory system to a constant stimulus. It is usually experienced as a change in the stimulus. For example, if one rests one's hand on a table, one immediately feels the table's surface on one's skin. Within a...

. This stabilization is often interrupted by floaters, especially when they tend to remain visible.

Floaters are particularly noticeable when looking at a blank surface or an open monochromatic space, such as blue sky. Despite the name "floaters", many of these specks have a tendency to sink toward the bottom of the eyeball, in whichever way the eyeball is oriented; the supine position (looking up or lying back) tends to concentrate them near the fovea, which is the center of gaze, while the textureless and evenly lit sky forms an ideal background against which to view them. The brightness of the daytime sky also causes the eyes' pupils to contract, reducing the aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are,...

, which makes floaters less blurry and easier to see.

Floaters are essentially changeless, and the most prominent continue to be seen in the field of vision for a lifetime. They are not uncommon, and do not cause serious problems for most people; they represent one of the most common presentations to hospital eye services. A survey of optometrists in 2002 suggested that an average of 14 patients per month per optometrist presented with symptoms of floaters in the UK. However, floaters are more than a nuisance and a distraction to those with severe cases, especially if the spots seem to constantly drift through the field of vision. The shapes are shadows projected onto the retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...

 by tiny structures of protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 or other cell debris discarded over the years and trapped in the vitreous humour. Floaters can even be seen when the eyes are closed on especially bright days, when sufficient light penetrates the eyelids to cast the shadows. It is not, however, only elderly people who are troubled by floaters; they can also become a problem to younger people, especially if they are myopic
Myopia , "shortsightedness" ) is a refractive defect of the eye in which collimated light produces image focus in front of the retina under conditions of accommodation. In simpler terms, myopia is a condition of the eye where the light that comes in does not directly focus on the retina but in...

. They are also common after cataract
A cataract is a clouding that develops in the crystalline lens of the eye or in its envelope, varying in degree from slight to complete opacity and obstructing the passage of light...

 operations or after trauma. In some cases, floaters are congenital.

Floaters are able to catch and refract light in ways that somewhat blur vision temporarily until the floater moves to a different area. Often they trick people who are troubled by floaters into thinking they see something out of the corner of their eye that really is not there. Most people come to terms with the problem, after a time, and learn to ignore their floaters. For people with severe floaters it is nearly impossible to completely ignore the large masses that constantly stay within almost direct view.
Floaters have been reported in patients as young as 6. Floaters in teenage patients and young adults are usually harder to treat. For people in this age group, the floater that is seen usually looks like a kind of crystal (translucent) worm/web/cell. These particular floaters aren't really floaters in a technical sense as they aren't found in the vitreous humour, instead they are found right on top of the retina in the Premacular Bursa. Very little is known about this region, and it only becomes distinct after the vitreous detaches from the retina
Posterior vitreous detachment
A posterior vitreous detachment is a condition of the eye in which the vitreous humour separates from the retina.Broadly speaking, the condition is common for older adults and over 75% of those over the age of 65 develop it. Although less common among people in their 40s or 50s, the condition is...

 at later stages of life. Due to their microscopic size they cannot be seen by professional doctors. They only appear as big as they do because of their proximity to the retina. These types of floaters are still described occasionally in the third decade and very rarely occur in the 40 or older population.


There are various causes for the appearance of floaters, of which the most common are described here. Simply stated, any damage to the eye that causes material to enter the vitreous humour can result in floaters.

There are websites that advise that causes of floater include, but may not be limited to- rubbing the eye, sleeping on the back or front, smoking, using eye drops or medication or illegal drugs. There is NO evidence to suggest that any of the above causes floaters. Floaters can be a sign of Retinal Detachment or a Retinal Tear but in most (98% according to NHS) cases it is simply age related or due to natural change in the vitreous humour. according to the UK 'Yellow Card Scheme' that allows people to report adverse effects of prescription drugs other than those stated there is one possible case of Ocular Zovirax causing floaters. This is the first (known) report of such a reaction and given the nature of the drug, used to treat Ocular Herpes which can take sight, it is a well understood and very useful drug with a low risk to use factor.

Vitreous syneresis

The most common cause of floaters is shrinkage of the vitreous humour: this gel-like substance consists of 99% water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

 and 1% solid elements. The solid portion consists of a network of collagen
Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...

 and hyaluronic acid, with the latter retaining water molecules. Depolymerization
Depolymerization is the process of converting a polymer into a monomer or a mixture of monomers.Thioglycolysis, thiolysis and phloroglucinolysis are reactions used to study condensed tannins by means of their depolymerisation. Thioglycolysis is also used to study lignin....

 of this network makes the hyaluronic acid release its trapped water, thereby liquefying the gel. The collagen breaks down into fibril
Fibril is a fine fiber approximately 1 nm in diameter.Cytoplasmic fibrils are observed on the protoplasmic cylinders found in most spirochetal species, although no function of the cytoplasmic fibrils has been ascribed....

s, which ultimately are the floaters that plague the patient. Floaters caused in this way tend to be few in number and of a linear form.

Posterior vitreous detachments and retinal detachments

In time, the liquefied vitreous body loses support and its framework contracts. This leads to posterior vitreous detachment
Posterior vitreous detachment
A posterior vitreous detachment is a condition of the eye in which the vitreous humour separates from the retina.Broadly speaking, the condition is common for older adults and over 75% of those over the age of 65 develop it. Although less common among people in their 40s or 50s, the condition is...

, in which the vitreous body is released from the sensory retina. During this detachment, the shrinking vitreous can stimulate the retina mechanically
A phosphene is a phenomenon characterized by the experience of seeing light without light actually entering the eye. The word phosphene comes from the Greek words phos and phainein...

, causing the patient to see random flashes across the visual field, sometimes referred to as "flashers", a symptom more formally referred to as photopsia
Photopsia is the presence of perceived flashes of light. It is most commonly associated with posterior vitreous detachment, migraine with aura, migraine aura without headache, retinal break or detachment, occipital lobe infarction and sensory deprivation...

. The ultimate release of the vitreous around the optic nerve head sometimes makes a large floater appear, usually in the shape of a ring ("Weiss ring"). As a complication, part of the retina might be torn off by the departing vitreous body, in a process known as retinal detachment
Retinal detachment
Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. Initial detachment may be localized, but without rapid treatment the entire retina may detach, leading to vision loss and blindness. It is a medical emergency.The retina is a...

. This will often leak blood into the vitreous, which is seen by the patient as a sudden appearance of numerous small dots, moving across the whole field of vision. Retinal detachment requires immediate medical attention, as it can easily cause blindness
Blindness is the condition of lacking visual perception due to physiological or neurological factors.Various scales have been developed to describe the extent of vision loss and define blindness...

. Consequently, both the appearance of flashes and the sudden onset of numerous small floaters should be rapidly investigated by an eye care provider.

Regression of the hyaloid artery

The hyaloid artery
Hyaloid artery
The hyaloid artery is a branch of the ophthalmic artery, which is itself a branch of the internal carotid artery. It is contained within the optic stalk of the eye and extends from the optic disc through the vitreous humor to the lens...

, an artery running through the vitreous humour during the fetal
A fetus is a developing mammal or other viviparous vertebrate after the embryonic stage and before birth.In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the 9th week after fertilization.-Etymology and spelling variations:The...

 stage of development, regresses in the third trimester of pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...

. Its disintegration can sometimes leave cell matter.

Other common causes

Patients with retinal tears may experience floaters if red blood cell
Red blood cell
Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...

s are released from leaky blood vessels, and those with a posterior uveitis or vitritis, as in toxoplasmosis
Toxoplasmosis is a parasitic disease caused by the protozoan Toxoplasma gondii. The parasite infects most genera of warm-blooded animals, including humans, but the primary host is the felid family. Animals are infected by eating infected meat, by ingestion of feces of a cat that has itself...

, may experience multiple floaters and decreased vision due to the accumulation of white blood cell
White blood cell
White blood cells, or leukocytes , are cells of the immune system involved in defending the body against both infectious disease and foreign materials. Five different and diverse types of leukocytes exist, but they are all produced and derived from a multipotent cell in the bone marrow known as a...

s in the vitreous humour.

Other causes for floaters include cystoid macular edema and asteroid hyalosis
Asteroid hyalosis
Asteroid hyalosis is a degenerative condition of the eye involving small white opacities in the vitreous humor. It is known to occur in humans, dogs, and chinchillas. Clinically, these opacities are quite refractile, giving the appearance of stars shining in the night sky—except that ocular...

. The latter is an anomaly of the vitreous humour, whereby calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...

 clumps attach themselves to the collagen network. The bodies that are formed in this way move slightly with eye movement, but then return to their fixed position.

Tear film debris

Sometimes the appearance of floaters has to be attributed to dark specks in the tear film
Tears are secretions that clean and lubricate the eyes. Lacrimation or lachrymation is the production or shedding of tears....

 of the eye. Technically, these are not floaters, but they do look the same from the viewpoint of the patient. People with blepharitis
Blepharitis is an ocular condition characterized by chronic inflammation of the eyelid, the severity and time course of which can vary. Onset can be acute, resolving without treatment within 2–4 weeks , but more generally is a long standing inflammation varying in severity...

 or a dysfunctional meibomian gland
Meibomian gland
The meibomian glands are a special kind of sebaceous gland at the rim of the eyelids inside the tarsal plate, responsible for the supply of meibum, an oily substance that prevents evaporation of the eye's tear film. They prevent tear spillage onto the cheek, trapping tears between the oiled edge...

 are especially prone to this cause, but ocular allergies
Allergic conjunctivitis
Allergic conjunctivitis is inflammation of the conjunctiva due to allergy. Although allergens differ between patients, the most common cause is hay fever. Symptoms consist of redness , oedema of the conjunctiva, itching and increased lacrimation...

 can also cause the problem. To differentiate between material in the vitreous humour of the eye and debris in the tear film, one can look at the effect of blinking: debris in the tear film will move quickly with a blink, while floaters are largely unresponsive to it. Tear film debris is diagnosed by eliminating the possibility of true floaters and macular degeneration
Macular degeneration
Age-related macular degeneration is a medical condition which usually affects older adults and results in a loss of vision in the center of the visual field because of damage to the retina. It occurs in “dry” and “wet” forms. It is a major cause of blindness and visual impairment in older adults...



Floaters are often readily observed by an ophthalmologist or an optometrist with the use of an ophthalmoscope or slit lamp
Slit lamp
The slit lamp is an instrument consisting of a high-intensity light source that can be focused to shine a thin sheet of light into the eye. It is used in conjunction with a biomicroscope...

. However, if the floater is near the retina, it may not be visible to the observer even if it appears large to the sufferer.

Increasing background illumination or using a pinhole to effectively decrease pupil diameter may allow a person to obtain a better view of his or her own floaters. The head may be tilted in such a way that one of the floaters drifts towards the central axis of the eye. In the sharpened image the fibrous elements are more conspicuous.

The presence of retinal tears with new onset of floaters was surprisingly high (14%; 95% confidence interval, 12%-16%) as reported in a metaanalysis published as part of the Rational Clinical Examination Series in the Journal of the American Medical Association. Patients with new onset flashes and/or floaters, especially when associated with visual loss or restriction in the visual field, should seek more urgent ophthalmologic evaluation.


The surgeon John Karickhoff has performed thousands of operations that have cured floaters with a 90% success rate.
  • Vitrectomy
    Vitrectomy is a surgery to remove some or all of the vitreous humor from the eye. Anterior vitrectomy entails removing small portions of the vitreous from the front structures of the eye—often because these are tangled in an intraocular lens or other structures...

     may be successful in treating more severe cases; however, the procedure is typically not warranted in those with lesser symptoms due to the potential for complications to include cataracts, retinal detachment, and severe infection. The technique usually involves making three openings through the part of the sclera
    The sclera , also known as the white or white of the eye, is the opaque , fibrous, protective, outer layer of the eye containing collagen and elastic fiber. In the development of the embryo, the sclera is derived from the neural crest...

     known as the pars plana
    Pars plana
    The pars plana is part of the uvea, choroidea, one of the three layers that comprise the eye. As a part of the ciliary body, it is about 4 mm long and located near the point where the iris and sclera touch....

    . Of these small gauge instruments, one is an infusion port to resupply a saline solution and maintain the pressure of the eye, the second is a fiber optic light source, and the third is a vitrector. The vitrector has a reciprocating cutting tip attached to a suction device. This design reduces traction on the retina via the vitreous material. A variant sutureless, self-sealing technique is sometimes used.

  • Laser
    A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...

     vitreolysis: In this procedure an ophthalmic laser (usually an Yttrium aluminium garnet
    Yttrium aluminium garnet
    Yttrium aluminium garnet is a synthetic crystalline material of the garnet group. It is also one of three phases of the yttria-aluminium composite, the other two being yttrium aluminium monoclinic and yttrium aluminium perovskite . YAG is commonly used as a host material in various solid-state...

     "YAG" laser) is focused onto the floater and in a series of brief bursts, the laser vaporizes and lyses (cuts) the collagen strands of the floater. As of July 2010, laser treatment is not widely practiced and is only performed by very few specialists in the world. It is an outpatient process, which is much less invasive to the eye than a vitrectomy, with potentially fewer side effects.

Descriptions in literature

  • "A common experience... is for a person who has some ocular trouble that impairs his vision to become suddenly aware of the so-called mouches volantes in his visual field, although the causes of this phenomenon have been there in the vitreous humor all his life. Yet now he will be firmly persuaded that these corpuscles have developed as the result of his ocular ailment, although the truth simply is that, owing to his ailment, the patient has been paying more attention to visual phenomena."

  • "They could have done the same thing, alone, in the back yard, seeing the shapes swimming in the sky. I forget how old I was when I asked somebody about it, and I was told that those wonderful gliding changing spots were imperfections in the fluid of my eye-ball, that what I was seeing was in my eye. In your eye! For so long, for a child's years, the sky was full of wonder, these shapes were in the sky, the sky was full of transparent things that swooped and swam. They were almost invisible, and, I thought, almost bodiless, they were there, but you could go right through them, they were animals that lived in the air. You see, we didn't go around talking about things like this. It's only now, when I am grown up and know everything, that I talk about this."

  • "At first the amoebae look like muscae volitantes, those curled moving spots you seem to see in your eyes when you stare at a distant wall. Then I see the amoebae as drops of water congealed, blusish, translucent, like chips of sky in the bowl."

See also

  • Blue field entoptic phenomenon, alias Scheerer's phenomenon
    Blue field entoptic phenomenon
    The blue field entoptic phenomenon or Scheerer's phenomenon is the appearance of tiny bright dots moving quickly along squiggly lines in the visual field, especially when looking into bright blue light...

     - tiny bright dots moving quickly in the visual field.
  • Phosphene
    A phosphene is a phenomenon characterized by the experience of seeing light without light actually entering the eye. The word phosphene comes from the Greek words phos and phainein...

  • Synchysis scintillans
    Synchysis scintillans
    Synchysis scintillans is a degenerative condition of the eye seen uncommonly in dogs, resulting in liquified vitreous humor and the accumulation of cholesterol crystals within the vitreous. It is also known as cholesterosis bulbi. The vitreous liquifies in a process known as syneresis...

External links

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