When it comes to the eye, the word “detachment” can sound quite scary. Immediately your brain may jump to thinking about retinal detachments, which are serious conditions the require immediate care.
A posterior vitreous detachment, or PVD, is a different type of detachment we will all likely be told we have at one point or another during our lifetime. This article is aimed to put your mind at ease and help you better understand what exactly a “PVD” is, and why we get those pesky floaters in our vision!
The eye has two main sections—the anterior chamber and the posterior chamber.
The anterior chamber is limited in the front by the cornea and the back by the lens.
The posterior chamber is limited in the front by the lens, and the back by the retina.
In order to keep the eye inflated so that it does not cave in on itself, it is filled by water-like substances.
The anterior chamber is filled with a fluid called the aqueous humor. The aqueous humor is formed by a structure called the ciliary body and is actually composed of filtrate from the blood to provide nutrition to the anterior eye structures.
The posterior chamber is filled with a fluid called vitreous humor that is more similar to Jell-O and consists of primarily water, collagen, and hyaluronic acid.
From birth, the vitreous humor is attached firmly to different parts of the posterior chamber, the strongest attachments are at the vitreous base, lens, optic nerve (where information exits the eye to be transported to the brain), macula (the region of the retina responsible for our best vision), and lastly and most weakly attached at the retinal blood vessels.
The vitreous is responsible primarily for structural support and shock absorption within the eye. It is a clear surface that transmits light, but does not directly play a role in the creation of vision.
The vitreous also is not made continuously. The vitreous humor we are born with is the vitreous humor we die with.
Like the rest of the body, aging changes the consistency of the vitreous humor!
Typically this is not a problem. However, as noted it is closely associated to the retina, and therefore needs to be watched carefully.
As we get older, the vitreous condenses in a process called vitreous syneresis. When this happens, the uniformity of the vitreous starts to break down and we get pockets of water and loose collagen fibers floating around in the vitreous.
These loose collagen fibers are what we see as floaters.
When the vitreous begins to condense, it pulls away from the retina. As mentioned before, it is tightly attached to the retina at certain points—sometimes the retina and the vitreous do not want to separate!
As the separating vitreous pulls on the retina to free itself, it can cause symptoms of flashes of light and an increased number of floaters due to the tractional pulling of the retina.
The entire process of the vitreous separating from the retina takes about 1-3 months. Once it is separated, the risk for retinal detachment secondary to a posterior vitreous detachment decreases to almost zero.
Many individuals will report to their eye doctor when experiencing the initial symptoms of a posterior vitreous detachment (mild floaters and flashes). Your doctor will likely want to see you back during this 1-3 month time span to ensure the vitreous has separated completely without creating any retinal tears or holes and monitor for retinal detachments during this process.
While uncommon, there are two major complications secondary to a posterior vitreous detachment that your doctor will want to watch for—retinal detachment and vitreomacular traction.
We’ve touched on retinal detachment briefly throughout this article—retinal detachments can occur secondary to a PVD when the adherence between the vitreous and retina is so strong that, as the vitreous condenses and separates from the retina, it pulls on the retina, creating enough traction that it eventually breaks, creating a hole or a tear.
The break in the retina may or may not cause a retinal detachment, but it greatly increases the risk for one to occur. The retinal break creates instability across the retinal surface. Over time, this instability may get tugged on again, essential ripping part of the retina open.
When part of the retina is tugged outward, it can become separated from the underlying layers below creating a retinal detachment. Retinal detachments can vary in size from small focal area(s) of detachment to a large area of detachment.
Retinal detachments are a medical emergency. When the retina detaches, it becomes separated from its blood and oxygen supply. It can only survive for a very short period of time before the retinal tissue dies completely.
Retinal cells cannot regenerate. There is currently no treatment to replace or revitalize dead retinal tissue. Thus, it is of upmost importance to get in to see your local ophthalmologist immediately for retina repair to try and save at least some of the vision affected by the detachment.
Signs of a retinal detachment include: a dramatic increase in floaters (suddenly you have 10 or more new floaters in your vision), flashes of light (commonly described as a “lighting bolt in vision” or “strobe light in the eye”), or a “curtain or veil” over your vision.
Retinal detachments are typically painless and can occur at any time. If an optometrist or ophthalmologist if off-hours and you think you are experiencing a retinal detachment, call 911 and get to a hospital with an ophthalmology department as quickly as possible.
Aside from random areas of retinal detachment, there are certain areas of vitreal-retinal adhesion that doctors play close attention to as the vitreous has strong attachments to different parts of the retina (vitreous base, lens, macula, optic nerve, retinal vessels).
The macula is the area of the eye responsible for your best, well-defined, central vision and is debatably the most important structure in the retina.
Vitreomacular traction can be temporary resulting in distorted or decreased vision temporarily until the vitreous is able to eventually pull away. In these situations, careful monitoring by your doctor is the appropriate treatment course.
In other cases, however, vitreomacular traction can cause more serious secondary affects including macular holes, epiretinal membrane formation, or macular edema—all of which can result in decline in vision.
Your doctor will want to watch this condition with OCT scans to determine the amount of risk involved and whether or not surgical intervention to purposely remove the vitreous, and thus eliminate the traction against the macula, is necessary.
Q: Is there a way to reattach the vitreous after it has separated?
A: No. This generally is not a problem as it does not anatomically create problems once separated.
Q: Will my floaters ever go away?
A: Not likely, however they will become less noticeable over time and “fade” into the background of your vision.
Q: Is there anything I can do to prevent a vitreous detachment?
A: No. A PVD is part of normal aging changes in the eye—we want to live long enough to experience this phenomenon!
Q: Does a vitreous detachment require treatment?
A: Typically, no. Your doctor will want to watch the condition by performing a dilated fundus exam to observe all aspects of the retina and watch for retinal tears or holes. He or she may recommend an OCT scan (a special test that takes a cross-sectional look at the retina) to better observe the process. In some rare and extreme cases, your doctor may refer you get the vitreous humor surgically removed and replaced with artificial vitreous, but this is unlikely secondary to a PVD.