Retinal Detachments

Persistent Flashes After Posterior Vitreous Detachment (PVD)

Updated by Mike Rosco, MD 3/8/23 6:52PM PST

It is not uncommon for the symptoms of flashes to persist after a posterior vitreous detachment, or PVD.  Flashes and floaters, common symptoms of a PVD, may also be warning signs of a possible retinal tear.  Retinal tears oftencause a retinal detachment.  Do persistent flashes mean increased risk for a tear or retinal detachment?

Ways to Stimulate the Retina

There are two ways to stimulate the retina. Light is the most common stimulus.  Light enters the eye and falls onto the retina producing vision. The second way to stimulate this inner lining of the eye is by physical manipulation. Ever rub your eyes so hard you see patterns of light?

Another example of physical stimulation of the retina is a posterior vitreous detachment. As we age, the back (posterior) portion of the vitreous gel inside your eye separates from the retina.  The anterior portion, however, remains adherent.  Simply remember that the back part of the vitreous separates, but the front part never does (and that’s where the tears occur).

Flashes from a PVD

Part of the vitreous is now free floating in the eye and the other part is “tethered” to the anterior retina. (Think of a flag pole. Half the flag is flapping freely in the wind, while the other half is attached to the pole.) As the eye moves, part of the vitreous is free floating, while the other portion is attached to the retina. The part still attached gently tugs, causing the perception of flashes as the retina is stimulated. If the tugging is too hard, the vitreous that is still adherent can pull the retina with it and create a tear. 

First 6 Weeks are the Scariest

The first six weeks following the initial symptoms of a PVD are the highest risk for developing a retinal tear. Statistically, this is the period when MOST retinal tears occur. There are exceptions.

It is during this period, as the vitreous separates from the retina, where the tugging forces change inside the eye.  Usually if a tear is to occur, it happens within days to weeks.  However, sometimes no tear is found yet the symptoms persist.

What Does This Mean? After the diagnosis of a posterior vitreous detachment is made, I recommend re-evaluation at 6 weeks after the initial symptoms began, or sooner if the symptoms worsen.

If the symptoms remain relatively the same, patients usually return at the 6-week mark.  I look for any new tears at the follow-up exam.  If none are found at the second exam and the symptoms have remained the same or decreased,I don’t ask for an additional  exam.

Persistent flashes are worrisome.  Are you at risk for a retinal tear? Studies vary, but generally speaking, if you experience these symptoms from a PVD, there is an 8-16% chance you will have a retinal tear. 

Persistent flashes occur because the vitreous remains adherent to the retina.  As we discussed, gentle tugging causes the flashes.  If you had a retinal tear, the vitreous is still adherent to the tear, and it, too, is stimulated by the moving vitreous.

This vitreous pulling, or “vitreous traction,” is common and may last a long time, even if you do not have a retinal tear.

The recommendation of retinal specialists (and the AAO) is that you seek re-examination urgently if the flashes INCREASE as this may be a sign of a new tear.

Flashes that persist, but are not increased, are probably not an indication of a greater risk of tear.  It is a sign that you’ve had a PVD.

Vitrectomy surgery can be performed  to alleviate the symptoms, though generally speaking, these symptoms are temporary and will resolve in time.

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Diabetic retinopathy Retina Treatments

Sometimes You Just Need a Vitrectomy

A vitrectomy is an eye operation. It is performed by retina specialists for a variety of reasons. In patients with diabetic retinopathy, a vitrectomy may be useful to remove blood in the vitreous, aka a vitreous hemorrhage. There is no reason, to perform a vitrectomy in cases of macular degeneration.

Vitrectomy Surgery to Clear Hemorrhage
Vitrectomy Surgery to Clear Hemorrhage

In cases of vitreous hemorrhage, bleeding has and blood remains suspended in the vitreous. The vitreous is the gel-like substance that fills most of the eye. It is very similar to jellyfish, it has substance, but is mostly water.  It is optically clear.

A vitreous hemorrhage is benign, that is, the blood does not cause any damage to any portion of the eye, especially the retina. The vitreous hemorrhage physically blocks light and causes loss of vision. Sometimes the vitreous hemorrhage can absorb on its own, but if not, a vitrectomy is necessary to remove the non-clearing vitreous hemorrhage. At this point vision should be restored. It can take weeks or months to absorb. Many times we can’t wait that long.

Advanced diabetic retinopathy, or proliferative diabetic retinopathy, can have a retinal detachment associated with it. This type of retinal detachment is different. Most retinal detachments are caused by a retinal tear or retinal hole, called a “rhegmatogenous” retinal detachment.

Retinal detachments associated with diabetic retinopathy are called “traction” retinal detachments. The mechanism is different than rhegmatogenous retinal detachments in that the retina is pulled, like a tent, apart from the underlying layers. “Scar” tissue has formed on the surface of the retina, contracted and exerts this pulling.

A vitrectomy is necessary to correct/repair this type of retinal detachment. The vitreous is removed to allow access to the retinal surface. The abnormal scar tissue is cut away to relieve the “pulling.”

Vitrectomy surgery is also used for other retinal problems; rhegmatogenous retinal detachments, epiretinal membranes, macular holes, floaters, certain trauma, etc. Major risks of the surgery include blindness from infection and retinal detachment. The risks, however, are very, very uncommon.

Vitrectomy surgery has been around  for about 30 years.  It has allowed us to prevent potentially blinding retinal detachments in our diabetic retinopathy patients.  On the other hand, the whole focus of this site is to educate.  If you are seen early enough, you’ll never even need a vitrectomy.


Randall V. Wong, M.D.
Ophthalmologist, Retina Specialist
Fairfax Virginia

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