There are various causes for the appearance of<unk> s, of which the most common are described here.<unk> s can occur when eyes age; in rare cases,<unk> s may be a sign of retinal detachment or a retinal tear. Vitreous syneresis The cause of a vitreous<unk>  is due to vitreous syneresis (liquefaction) and contraction with age. Additionally, trauma or injury to the globe can cause vitreous<unk> s. Vitreous detachments and retinal detachments Weiss ring: a large, ring shaped<unk>  that is sometimes seen if the vitreous body releases from the back of the eye In time, the liquefied vitreous body loses support and its framework contracts. This leads to posterior vitreous detachment, in which the vitreous membrane 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 the visual field, sometimes referred to as "flashers", a symptom more formally referred to as photopsia. The ultimate release of the vitreous around the optic nerve head sometimes makes a large<unk>  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 membrane, 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. Consequently, both the appearance of flashes and the sudden onset of numerous small<unk> s should be rapidly investigated by an eye care provider. Posterior vitreous detachment is more common in people who: * are nearsighted; * have undergone cataract surgery; * have had Nd:YAG laser surgery of the eye; * have had inflammation inside the eye. Regression of the hyaloid artery The hyaloid artery, an artery running through the vitreous humour during the fetal stage of development, regresses in the third trimester of pregnancy. Its disintegration can sometimes leave cell matter. Other common causes Patients with retinal tears may experience<unk> s if red blood cells are released from leaky blood vessels, and those with uveitis or vitritis, as in toxoplasmosis, may experience multiple<unk> s and decreased vision due to the accumulation of white blood cells in the vitreous humour. Other causes for<unk> s include cystoid macular edema and asteroid hyalosis. The latter is an anomaly of the vitreous humour, whereby 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.
Floater
Boil
BoRit Asbestos
Drustbed
Straw 
Dream
Snake
Wart