Even eyeballs age. As you edge over 50, the vitreous—the clear gel-like substance inside your eyes—begins to liquefy and shrink. Within the gel are millions of fibers attached to the retina, the light-sensitive nerve tissue lining the interior of the eye. As the gel shrinks, the fibers break, allowing the vitreous to peel away from the retina, a process called posterior vitreous detachment (PVD). This event occurs in everyone as they get older.
Symptoms to watch for
Most of the time, the development of PVD doesn’t cause any problems for eye health, and typically no treatment is needed. PVD develops in most people older than 60. In some cases, the symptoms are hardly noticeable, and most patients never have complications.
When PVD occurs, you may develop floaters—these appear as spots, specks, strings, or cobwebs—that move or swim as you move your eyes. The floaters are actually clumps of gel, fibers, and cells floating in the liquefied portions of the vitreous; what you see are the shadows they cast on the retina. Usually they are merely annoying. The brain often adapts so that within about six months you seldom pay attention to them anymore.
A sudden appearance or an increase in the number of typical floaters may announce PVD, as may flashes of light. These arise as the separating vitreous tugs on the retina, stimulating cells that send a message of light to the brain. In some cases, this pulling may break a blood vessel in the retina, resulting in what’s called a vitreous hemorrhage. The rupture of a retinal blood vessel may produce a shower of floating spots. If the hemorrhage is dense, a dark blob may appear that may even eclipse vision, dropping like a curtain before the eye.
To check for PVD, an eye doctor will dilate your pupil with eye drops and use a special lens to view the vitreous and the retina. If you do have PVD, often the physician will see a ring of the vitreous fibers floating in the vitreous cavity (a Weiss ring). This represents the site where the vitreous was formerly attached to the retina at the optic nerve.
After the initial exam, most patients should have a follow-up exam in about three months, or sooner if symptoms increase.
When detachment is risky
In some people who have PVD with symptoms, some of the vitreous fibers have an abnormally strong adhesion and pull so hard as they naturally separate from the retina that they create a tear or hole in the retina, especially in the thin retinal peripheral tissue. Vitreous fluid then has the opportunity to travel or pass through the tear, which can cause the retina to detach from the back wall of the eye.
This is a sight-threatening situation: If the tear is not repaired, the retina can detach completely. That happens rarely in individuals with PVD, but the prevalence leaps when a vitreous hemorrhage is involved. That’s why it’s essential to see an ophthalmologist promptly—within 24 to 72 hours—if you have any symptoms of PVD. At the greatest risk are people over age 50 and those with eye injury, inflammation, or diabetic retinopathy (retinal damage due to diabetes).
The risk of PVD and subsequent retinal detachment can be a rare complication of cataract surgery. Vitreous fluid may leak from the eye during the surgery, speeding up normal shrinkage of the vitreous gel and the risk of retinal tears.
Those who are significantly nearsighted are also at greater risk, because the egg-like shape of their eye (as compared with the Ping-Pong-ball shape of the normal eye) increases the pull of the vitreous on the retina. And the retina is thinner in myopic (nearsighted) eyes, making it more apt to tear.
Surgical solutions for retinal tears
The first challenge in fixing a tear due to PVD is locating the break in the retina—a difficult process, because many breaks occur on the far edge of the retina. The ophthalmologist will likely examine the retina with a lighted instrument called an indirect ophthalmoscope and may also use ultrasonography, or sound waves, creating an image that shows the condition of the retina.
Caught early, before detachment starts, a retinal tear can be sealed with laser or cryotherapy (freezing). Either method creates a scar in the retina, gluing the torn retina to the underlying eye wall so that it is less likely to be peeled off. Laser is generally used if the tear is located in a position that can be reached with an indirect laser ophthalmoscope or by placing a contact lens on the eye to direct the path of the laser light.
If the tears are very peripheral, they may be too difficult to reach with laser. In this case, the ophthalmologist may use cryotherapy, first numbing the eye and then using a probe to freeze the outer eye beneath the tear, helping it to seal.
Recovery from these procedures takes just a few days, but the scar may take several weeks to form; a person is still at risk for retinal detachment during this period. Usually the procedures done to seal tears do not affect the vision.
If the retina has a larger detachment, the doctor may perform a procedure called pneumatic retinopexy. After the tear is treated, a gas bubble is injected into the vitreous. With proper positioning of the head, the pressure of the gas bubble pushes the tear back against the wall of the eye, ensuring that the retina is next to the eye wall so that a scar develops between the retina and the underlying tissues in response to the laser or cryotherapy. The bubble gradually disappears over days or weeks.
A surgical option for partial retinal detachment is scleral buckling, which is successful in most patients. After the tear has been sealed using laser or cryotherapy, the ophthalmologist wraps a scleral buckle, or tiny silicone band, around the eye, which also helps reduce the vitreous pull that caused the tear. Another procedure for retinal detachment is a vitrectomy, whereby the the doctor removes the remaining vitreous gel, preventing further tugs on the retina. The effect on vision depends on whether the central part of the retina, or macula, was detached and for how long.
Preventing complications of PVD
Although you can’t prevent PVD, you can try to avoid its repercussions by alerting your doctor at the first sign of floaters, flashes of light, or any change in side (peripheral) vision. It is usually possible to repair a retinal tear, but a tear can also evolve quickly to retinal detachment. So don’t wait to see whether floaters discontinue when you suddenly begin to notice lots of them. Even if no retinal tear is present, your doctor can help you stay alert for that possibility.
Also see Protecting Your Aging Eyes.
Published July 24, 2019