Opacities that seem to move over a person’s vision are often called eye floaters. Floaters coincide with changes in the back of the eye. The back of the eye is filled with a dense gel, called the vitreous. This gel breaks down over time and becomes more water-like. This is called syneresis. The gel can also combine to form vitreal strands. When either of these things happen, it is interpreted as floating dots or strands in one’s vision as it creates a shadow on the underlying retina.
As we age, the more likely this vitreous is to detach from the retina underneath. The technical term for this is a posterior vitreal detachment (PVD). In these cases, patients often complain of a sudden onset of a floater(s). Posterior vitreal detachments tend to lead to larger floaters and can also be accompanied by a flash of light. While posterior vitreal detachments are most common in older populations, younger individuals can also experience them. Cases of ocular trauma can cause posterior vitreal detachments and all cases of ocular trauma should be assessed by an eye care professional.
These detachments can be unilateral (one eye) or bilateral (both eyes). After one PVD, the chances increase for the other eye to experience the same or similar in the following weeks. For this reason, patients are monitored closely after the first PVD occurs.
Both vitreal syneresis and posterior vitreal detachments are benign conditions. Over time, the body adapts to the shadows the vitreous casts, and the brain can tune the floaters out. The brain can do this throughout a person’s life, as it similarly tunes out the blood vessels in the back part of the eye.
Flashes of light can be more concerning. Flashes are often caused by tugging or pulling of the retina. Tugging of the retina is caused by the vitreous detaching or new blood vessels pulling on the retina, like in uncontrolled diabetes. The vitreous can often detach without causing holes or tears but occasionally holes and tears may form. Holes and tears need to be sealed quickly because fluid can leak underneath the retina causing a retinal detachment and permanent vision loss. Flashes of light with MANY floaters are more concerning for this type of problem. The many floaters associated with holes and tears are red blood cells released from the area damaged.
In even more rare circumstances, floaters can be associated with inflammatory or immune disorders such as rheumatoid arthritis. The floaters that patients experience in these cases are caused by the inflammatory cells and byproducts in the vitreous itself. In these cases, a complete health physical needs to be performed to determine the underlying cause of the inflammation.
It is important to have any new onset of floaters evaluated by an eye care professional. While floaters are most commonly harmless, they can be more concerning in cases of inflammation, retinal tears, holes, and detachments. Dilated eye examinations allow eye doctors to assess the entire back of the eye to determine which kind of floater is obscuring your vision.