Floaters and degenerative vitreous
What floaters are, when they need attention, and whether treatment is appropriate.
What are floaters?
Floaters, also known as symptomatic vitreous opacities, are shapes that drift across your vision — small black dots, squiggly lines, or large cobweb shapes — caused by debris floating in the vitreous gel inside the eye. They can also cause a non-specific reduction in the quality of vision, particularly contrast sensitivity. Short-sighted people tend to get them younger, and they increase with age. They are most noticeable against bright backgrounds such as white walls or computer screens, where light is obstructed by clumps in the vitreous and casts shadows on the retina. Some floaters have a "snow-globe" effect, becoming very noticeable when you get up from lying down or move your head briskly.
What causes them?
The vitreous gel is made mainly of water with a collagen meshwork. With age, this meshwork breaks down in a process called vitreous syneresis: liquid lakes form and the solid parts clump into strands that cast shadows on the retina. In about 70% of people, by age 70, the liquefied gel collapses and peels away from the retina — a posterior vitreous detachment. This often causes a sudden new cobweb-like floater. As the vitreous gel peels away it can cause intermittent flashing lights, which usually subside over 4–12 weeks, though in some patients it may take a little longer.
Bleeding inside the eye, inflammation, and retinal pigment from a retinal tear or detachment can also cause floaters.
When do floaters need urgent attention?
In the vast majority of cases floaters are harmless. However, during a posterior vitreous detachment the vitreous can tear the retina, which may lead to retinal detachment. A marked shower of new floaters with flashing lights, or a curtain or shadow in peripheral vision, requires urgent examination by an eye doctor.
Treatment options
Since floaters are usually harmless, treatment is generally not recommended. Most people find they become much less noticeable over time as the brain adjusts and filters them out.
For people with very severe floaters that significantly affect quality of life, vitrectomy surgery can remove the vitreous gel and with it the floaters. There are two main approaches:
Floater-only vitrectomy (FOV / core vitrectomy)
Removes only the central body of the gel containing the floaters, leaving the vitreous attached to the retina. This reduces the risk of retinal tears during surgery and reduces the risk of early cataract. However, the residual attached vitreous will separate at some point in the future, which may cause new floaters months or years later.
Complete vitrectomy
Removes as much vitreous gel as possible, including peeling it from the retinal surface. Carries a higher risk of retinal tears during surgery, but reduces the risk of future floaters as there is no gel left to separate spontaneously. A higher risk of earlier cataract development.
Risks of vitrectomy for floaters
- Cataract — the most common side effect. May develop 2–3 years after surgery, occasionally sooner. One reason surgery is avoided in younger patients.
- Retinal detachment — occurs in about 4% of patients and requires further surgery.
- Severe loss of vision — extremely rare (approximately 1 in 1,000 cases) due to severe bleeding or infection.