Posterior vitreous detachment (PVD) is caused by age-related changes to the gel that fills the inside of your eye. As you get older, this gel gradually breaks down, shrinks, and eventually pulls away from the retina at the back of the eye. It’s extremely common, affecting the majority of people by their 70s and 80s, and while it’s usually harmless, understanding what triggers it helps you recognize when something more serious might be happening.
How the Vitreous Changes With Age
The vitreous is a clear, jelly-like substance that fills about 80% of your eye’s interior. In youth, it has a smooth, uniform consistency, held together by an even distribution of collagen fibers and hyaluronic acid (a molecule that traps water and keeps the gel hydrated). These two components work together: the collagen provides structure, and the hyaluronic acid keeps the collagen fibers spaced apart and the gel transparent.
Starting in your 40s and accelerating from there, the gel begins to break down in a process called syneresis. The collagen fibers thicken, twist together, and clump into visible strands. At the same time, pockets of liquid form within the gel as the hyaluronic acid loses its ability to maintain the gel’s structure. The vitreous slowly transitions from a firm, homogeneous jelly into a mix of liquid and fibrous clumps. As the gel’s total volume shrinks, it begins to pull away from the retina, starting near the center and eventually separating from the optic nerve at the back of the eye. That final separation is what doctors call a posterior vitreous detachment.
Why Age Is the Primary Cause
Age is the single biggest factor. The breakdown of collagen and hyaluronic acid is a natural, inevitable part of aging. Most people experience PVD by their mid-60s to 70s, and it typically happens in both eyes, though not always at the same time. If it occurs in one eye, the other eye often follows within a year or two.
Nearsightedness (myopia) accelerates this timeline. People with moderate to high myopia have longer eyeballs, which stretches the vitreous thinner and speeds up the liquefaction process. PVD can occur a full decade or more earlier in highly myopic eyes compared to eyes with normal vision.
Cataract Surgery and Eye Trauma
Cataract surgery is one of the most well-documented non-aging causes of PVD. A large prospective study from the American Academy of Ophthalmology tracked 575 eyes that had no vitreous detachment before surgery and found that 30% developed PVD within three years afterward. The progression was steady: about 3% at one month, 8% at six months, 11% at one year, and continuing to climb through the three-year mark. The surgery itself changes the internal environment of the eye, removing the natural lens and altering the dynamics of the vitreous in ways that promote earlier separation.
Eye trauma can also trigger PVD. A blow to the eye or head can cause sudden mechanical stress on the vitreous, pulling it away from the retina abruptly rather than gradually. Other eye surgeries and inflammatory conditions inside the eye can have a similar effect.
What It Feels Like
PVD typically announces itself with two hallmark symptoms: floaters and flashes. Floaters appear as dark spots, cobwebs, or thread-like shapes drifting across your vision. They’re caused by those clumped collagen fibers casting shadows on your retina. Flashes of light, which often look like brief streaks or sparkles in your peripheral vision, happen when the separating vitreous tugs on the retina and stimulates the light-sensitive cells there.
The process usually starts as a partial detachment near the center of the retina and produces no symptoms at that stage. Symptoms typically begin once the separation reaches the optic nerve at the back of the eye. At that point, a ring-shaped piece of tissue called a Weiss ring often peels away from around the optic nerve and floats into the vitreous. This ring is sometimes visible as a large, circular floater and is the hallmark sign eye doctors look for to confirm a complete PVD.
For most people, the floaters and flashes are mild and become less noticeable within a few months. The vitreous doesn’t reattach, and the floaters don’t truly disappear, but your brain gradually learns to filter them out. Over time, they settle lower in the eye and drift out of your central line of sight.
When PVD Leads to Complications
The vitreous doesn’t always separate cleanly. In some spots, it can be more firmly attached to the retina, and when it pulls away, it can tear the retinal tissue. A study published in Ophthalmology Retina that analyzed 9,635 eyes found that 25% of people with symptomatic PVD developed some type of complication. Retinal breaks (tears without full detachment) occurred in 16% of eyes, and full retinal detachment occurred in 4.2%.
Most complications showed up at the initial visit, but not all of them. Among retinal detachments, about 26% were first detected during the six-month follow-up period rather than at the first exam. Retinal breaks that developed later accounted for about 19% of all breaks found. This is why eye doctors typically schedule follow-up exams after diagnosing a PVD, even if the initial exam looks clean.
Vitreous hemorrhage, or bleeding inside the eye, occurred in about 13% of cases and was a particularly important warning sign. Among eyes that had bleeding at their first visit, 42% were found to also have a retinal tear either at that time or later, and about 10.5% had a retinal detachment. A sudden increase in floaters, a shower of new floaters, flashes that become more frequent, or a shadow or curtain creeping across your vision are all signals that the separation may have caused a tear.
Other Contributing Factors
Diabetes can alter the vitreous in complex ways. In some cases it causes abnormal attachments between the vitreous and retina, making the eventual separation more likely to cause traction or tearing. Inflammation inside the eye from conditions like uveitis can also weaken the vitreous structure and promote earlier detachment. People who have experienced PVD in one eye are at higher risk of it happening sooner in the other eye, which suggests individual biochemistry plays a role beyond just age.
There’s no proven way to prevent vitreous detachment. It’s a normal consequence of aging, much like graying hair or stiffening joints. The collagen and hyaluronic acid in the vitreous will break down over time regardless of diet, supplements, or lifestyle choices. What matters most is recognizing the symptoms when they appear and getting a prompt eye exam to rule out retinal tears, especially in the first few weeks after symptoms begin.