Als asked in Science & MathematicsMedicine · 1 decade ago

what are the specks of dots and worm-like objects that appear in vision when looking at the sky?

are they common?

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  • Anonymous
    1 decade ago
    Favourite answer

    Floaters are deposits of various size, shape, consistency, refractive index, and motility within the eye's normally transparent vitreous humour[1]. They may be of embryonic origin or acquired due to degenerative changes of the vitreous humour or retina[1]. The perception of floaters is known as myodesopsia, or less commonly as myiodeopsia, myiodesopsia, or myodeopsia[1]. When observed subjectively, floaters are entoptic phenomena characterized by shadow-like shapes which appear singly or together with several others in one's field of vision. They may appear as spots, threads, or fragments of cobwebs, that float slowly before one's eyes.

    Muscae volitantes (Latin: 'flying flies'), or mouches volantes, are a specific type of floater consisting of small spots whose presence is normal and attributed to minute remnants of embryonic structures in the vitreous humour[1]

    Contents

    [hide]

    * 1 Description

    * 2 Causes

    o 2.1 Vitreous syneresis

    o 2.2 Posterior vitreous detachments and retinal detachments

    o 2.3 Regression of the hyaloid artery

    o 2.4 Other common causes

    o 2.5 Tear film debris

    * 3 Treatment

    * 4 Observing floaters

    * 5 Quotations

    * 6 References

    * 7 See also

    * 8 External links

    [edit]

    Description

    Floaters are suspended in the vitreous humour, 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. Floaters located slightly to the side of one's direction of gaze can be particularly annoying. 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 (and thus not annoying) because they are fixed in location relative to the retina, and the brain "tunes out" stabilized images (see neural adaptation). This does not occur with floaters and they remain visible, and, in some cases when large and numerous, very annoying.

    Floaters are particularly noticeable when lying on one's back and gazing at 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 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.

    Floaters are not uncommon, and do not cause problems for most sufferers. 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 by tiny structures of protein or other cell debris discarded over the years and trapped in the vitreous humour. It should also be noted that they 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 suffer from floaters; they can certainly become a problem to younger people, especially if they are myopic. They are also common after cataract operations or after trauma. In some cases, floaters are congenital.

    [edit]

    Causes

    There are various causes for the appearance of floaters, of which the most common are described here. Basically, any way by which material enters the vitreous humour is a cause for floaters.

    [edit]

    Vitreous syneresis

    The most common cause of floaters is shrinkage of the vitreous humour: this gel-like substance consists of 99% water and 1% solid elements. The solid portion consists of a network of collagen and hyaluronic acid, with the latter retaining water molecules. Depolymerisation of this network makes the hyaluronic acid release its trapped water, thereby liquefying the gel. The collagen breaks down into fibrils, 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.

    [edit]

    Posterior vitreous detachments and retinal detachments

    In time, the liquefied vitreous body loses support and its framework contracts. This leads to posterior vitreous detachment, in which the vitreous body is released from the sensory retina. During this detachment, the shrinking vitreous can stimulate the retina mechanically, causing the patient to see random flashes across his visual field, sometimes referred to as "flashers." The ultimate release of the vitreous sometimes makes a large floater appear, usually in the shape of a ring. As a complication, part of the retina might be torn off by the departing vitreous body, in a process known as retinal detachment. 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. Both the appearance of flashes and the sudden onset of numerous small floaters warrant an ophthalmological investigation.

    [edit]

    Regression of the hyaloid artery

    The hyaloid artery, an artery running through the vitreous humour during the foetal stage of development, regresses in the third trimester of pregnancy. Its disintegration can sometimes leave cell matter.

    [edit]

    Other common causes

    Patients with retinal tears may experience floaters if red blood cells are released from leaky blood vessels, and thoses with a posterior uveitis or vitritis, as in toxoplasmosis, may experience multiple floaters and decreased vision due to the accummulation of white blood cells in the vitreous humour [1].

    Other causes for floaters include cystoid macular edema and asteroid hyalosis. The latter is an anomaly of the vitreous humour, where by calcium 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.

    [edit]

    Tear film debris

    Sometimes the appearance of floaters has to be attributed to dark specks in the tear film of the eye. Technically, these are not floaters, but they do look the same from the viewpoint of the patient. People with blepharitis or a dysfunctional meibomian gland are especially prone to this cause, but ocular allergies or even the wearing of contact lenses can 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.

    [edit]

    Treatment

    Normally, there is no treatment indicated. Vitrectomy may be successful in treating more severe cases[2], however, the procedure is typically not warranted in those with lesser symptoms due to the potential for complications. Floaters may become less annoying as sufferers grow accustomed to them, even to the extent that they may no longer notice them.

    Another treatment is laser vitreolysis. In this procedure a YAG laser is focused onto the floater and in a quick burst vaporizes the structure into, presumably, a less dense and not as noticeable consistency. This procedure can be time consuming and there is no consensus as to how completely effective it is. One study found laser vitreolysis "to be a safe but only moderately effective primary treatment conferring clinical benefit in one third of patients".[3]

    [edit]

    Observing floaters

    Floaters are often readily observed by a doctor with the use of an ophthalmoscope or slit lamp. However, if the floater is a small piece of debris and near the retina they may not be able to observe it 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. (If the pinhole is kept moving slowly in small circles, the same technique evokes an interesting entoptic effect known as the vascular figure, which is a view of the blood vessels within one's own eye.)

  • 4 years ago

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    Source(s): Effective Eye Floaters Treatment - http://eyefloaters.iukiy.com/?gTOV
  • 1 decade ago

    I've heard them called "floaters" before, but I can't be certain that this is the correct term and not just a colloquialization. At any rate, they are totally common. As you know, your eyes are filled with a liquid to keep them pressurized as orbs. Occasionally bits of tissue will separate from the inside of your eye and float around until they dissolve. The specks and "worm-like objects" you're seeing are actually bits of cell material from within your eye.

    Nothing to worry about.

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  • Anonymous
    6 years ago

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  • 1 decade ago

    My optician told me that floaters are tiny haemorages in the vitrious humour (jelly like substance making up a large part of the eye). They can occur as your eye changes shape with age or missuse and never go away. Most of the time our clever brains can ignore them and give us a clear image but sometimes while looking at the sky or for other reasons, we become aware of them. I started seeing them as I became long sighted.

  • 1 decade ago

    Not sure anyone knows. Most people say they are "floaters" while others say you are actually seeing red blood cells meandering through capillaries. Problem with the floater theory is, why do you only see them intermittently? Problem with the red blood cell theory, red blood cells are microscopic, I'm not sure they would register as discrete objects to the human eye.

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    5 years ago

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  • Anonymous
    6 years ago

    Myopia is nearsightedness where a patient can see clearly objects which are close but not which are further away

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  • Jane
    Lv 4
    5 years ago

    For the best answers, search on this site https://smarturl.im/aD13L

    They are white blood cells going through the blood vessels in the back of your eye. The Wiki article has information about this and other similar phenomena.

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