Floaters are visible either because of the shadows that imperfections cast on the retina,[6] or because of the refraction of light that passes through them, and can appear alone or together with several others as a clump in one's visual field.

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, and the brain "tunes out" stabilized images through neural adaptation.

[7] The brightness of the daytime sky also causes the eyes' pupils to contract, reducing the aperture, which makes floaters less blurry and easier to see.

Floaters can even be seen when the eyes are closed on especially bright days, when sufficient light penetrates the eyelids to cast the shadows.

For persons with severe floaters it is nearly impossible to ignore completely the large masses that constantly stay within almost direct view.

[citation needed] In the case of young people, particularly those under 35, symptomatic floaters are likely suspended within a posterior region of the eye known as the pre-macular bursa.

Research on floaters of the pre-macular bursa is minimal, and safe treatment for patients with this disturbance that does not warrant major vitrectomy has yet to be discovered.

[14][9] As part of the normal human aging process the liquefied vitreous body loses support and contracts.

This will often leak blood into the vitreous, which is seen by the patient as a sudden appearance of numerous small black dots or ribbons moving across the field of vision.

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

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.

[20] The presence of retinal tears with new onset of floaters was surprisingly high (14%; 95% confidence interval, 12–16%) as reported in a meta-analysis published as part of the Rational Clinical Examination Series in the Journal of the American Medical Association.

Looking up/down and left/right will cause the floaters to leave the direct field of vision as the vitreous humour swirls around due to the sudden movement.

As of 2017[update], insufficient evidence is available to compare the safety and efficacy of surgical vitrectomy with laser vitreolysis for the treatment of floaters.

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.

However, YAG lasers have traditionally been designed for use in the anterior portion of the eye, i.e. posterior capsulotomy and iridotomy treatments.

As a result, they often provide a limited view of the vitreous, which can make it difficult to identify the targeted floaters and membranes.

"[31] Enzymatic vitreolysis has been trialed to treat vitreomacular adhesion (VMA) and anomalous posterior vitreous detachment.

[32] Dropping low doses of atropine onto the eye dilates the pupil, thus reducing shadow formation on the retina by floaters.

[35] So far, there have been studies using colloidal gold or indocyanine green (ICG) injected into the eye followed by a low-energy laser to target problematic floaters, and this has shown to be successful on vitreous opacities obtained during vitrectomy and in rabbits.

[14] It has been theorized that non-human animals are capable of seeing floaters, as most mammals have anatomically similar eye structures to humans.