Eye floaters are the visual perceptions of spots that swim or move on your visual field. They are very common and usually do not cause any complications.
What causes Eye Floaters
There are causes that occur as a natural aging process and causes that occur due to pathological diseases or changes.
1- Natural causes
The eye consists of two segments, the anterior segment which lies infront of the lens and is filled with aqueous humor which is a translucent fluid that is secreted by ciliary process while the posterior segment is filled with vitreous humor. Read more about Vitreous Syneresis.
Posterior vitreous detachment
Another normal mechanism of floaters is posterior vitreous detachments or PVD. Normally there are adhesions between the back surface of the vitreous or posterior vitreous face and the retina... Read more about Posterior Vitreous Detachment.
Can cause transient floaters which can remain from few seconds to few hours and usually can be associated with flashes of light and your doctor should be able to differentiate between migraine as a cause of floaters or retinal detachments because both are associated with flashes of light.
2- Pathological causes in the vitreous body
Floaters in vision can also be caused by abnormal deposits in the vitreous which can be white blood cells, red blood cells, drug remnants, parts of the cataract and retinal flaps. Read more about Pathological causes of Eye Floaters.
3- Pathological diseases in the anterior segment
Corneal opacities can give the perception of black spots in the visual field but these black spots do not move with eye movements. The presence of foreign body on the cornea also can give the perception of black spots.
Hemorrhage in the anterior chamber due to iris neovascularization or trauma, parts of the cataract after cataract surgery, silicone oil droplets or gas bubble in the anterior chamber after vitrectomy surgery; all can give the perception of floaters.
4- Pathological diseases of Retina, Optic Nerve or Visual Pathway
Retinal diseases and diseases of the optic nerve and visual pathway from the optic nerve to the brain can cause defects on visual field which will be seen by the patient as black spots or patches of varying sizes.
Those spots do not move with eye or head movements and can be mistaken as floaters.
5- After surgeries and laser procedures
It can occur after cataract surgery and also after YAG laser capsulotomy