What is the vitreous?
Before discussing what posterior vitreous detachment (PVD) is, you need to understand the term “vitreous.”
The hollow of your eye is filled with transparent gelatin between the lens and the retina. Called the vitreous body or vitreous humor, the name is derived for the Latin word “Vitreus” meaning glassy or transparent.
The vitreous makes up about 80% of the total volume of the eye and is 99% water and 1% collagen and hyaluronic acid. Free of blood vessels, light can pass unfettered through the eye to the retina, the light-capturing part of the eye that enables vision.
Part of the normal process of aging within the eye is when the vitreous gel with passaging time develops spaces, which tend to collapse on themselves. This can cause the vitreous to detach in various places from the retina.
Around 65 percent of people by the time they’re 65 have some posterior vitreous detachment, so it’s a universal part of the aging process.
Posterior means the backside, so we are talking about the backside the of vitreous body becoming detached at some level. Thus – Posterior Vitreous Detachment.
Symptoms of PVD
Two of the common symptoms of PVD are flashes of light and “floaters.”
Most people, especially those with myopia (nearsightedness), may be familiar with floaters; objects that move with the eye’s movement around in the field of vision that look like blobs, little worms, or cobwebs. Floaters will show up when looking at a bright plain background such as a blank computer screen or blue sky.
How PVD causes floaters and flashes of light
With posterior vitreous detachment, people will see floaters and they may see flashes of light.
Floaters result from pockets of fluid suspended in the vitreous body that cast shadows on the retina.
As they get closer to the retina, they will appear larger and clearer.
The vitreous is mainly composed of collagen and hyaluronic acid, two substances that are found in many parts of the body such as the skin and joints.
The collagen gives the vitreous its solid structure and the hyaluronic acid contributes to its volume with the water it holds. As our eyes age, the water starts to separate from the collagen in a process called synchysis (liquefaction) and syneresis (contraction).
This creates pockets of fluid that are seen as blobs or little worms. Also, the collagen fibrils losing their water will mass together and appear as floating cobwebs or strings.
Flashes of Light
The fluid pockets created from syneresis can collapse. When this happens, the vitreous can pull away causing vitreous detachment from the retina and produce flashes of light (photopsias) in peripheral vision.
Visual acuity can be negatively impacted by a range of diseases that affect the vitreous such as diabetic hemorrhage, but floaters are expected and common with age-related changes.
Vitreous Detachment Vs Retinal Detachment
It should be noted that PVD is not the same as retinal detachment, a much more serious event than vitreous detachment. An optometrist, particularly a retinal specialist, can differentiate between a vitreous detachment and a potential eyesight-threatening retinal detachment.
Risks of PVD
Age-related PVD – The risk of experiencing vitreous detachment increase with age. This typically happens anytime between 40 and 70 years of age, but for some people, it could be later. People with a high degree of myopia (nearsightedness) could be younger when they start seeing floaters.
Myopia can increase the risk of vitreous detachment
Myopia is caused by the eyeball’s shape being too long, causing images to be in front of the retina instead of on the retina.
This longer shape increases the risk of PVD and the risk of retinal complications. With the retina is stretched over a larger surface, it becomes thinner and more vulnerable to tears.
While vitreous detachment is normal, it is not normal for the vitreous to pull or tear the retina. This pulling away can sometimes cause a break in the retina leading to retinal detachment, a serious problem that would need to be treated immediately.
Additional risk factors for PVD – include trauma or a recent eye surgery such as a cataract operation. People who have PVD in one eye will often have PVD in the other eye within 1 year.
How long do the symptoms of posterior vitreous detachment last?
With a posterior vitreous detachment, the floaters and flashes of light due to the vitreous pulling on the retina should generally dissipate in several weeks to several months.
Once the vitreous is detached, however, it may not be detached completely. There can be one set of symptoms as the vitreous detaches a slight amount, then it can detach a little further to completion.
As long as there is no tear in the retina or retinal detachment, one should not worry, 85% of patients with PVD never develop complications.
Posterior vitreous detachment can be diagnosed with a normal dilated eye examination. Sometimes the vitreous gel may be too clear to see the PVD. Then your retinal specialist may use Optical Coherence Tomography (OCT), a non-invasive imaging test or non-invasive Ocular Ultrasound.
People may complain of a few floaters, but it really doesn’t bother them. As time goes by after the development of PVD, the vitreous gel drops out of sight and the patients get used to the floaters.
There are some patients in whom the floaters become very difficult, interfering with their lifestyle. If they are particularly dense, they can obstruct the vision and interfere with their ability to read. Vitreous detachment can be treated in the vast majority of these troublesome cases.
There are two treatment options. The optometrist can use a laser to disrupt the floaters, but this has varying success and often the symptoms come back. The second option, and a more permanent solution, is to remove the vitreous gel with a vitrectomy, a surgical procedure performed by a retinal specialist.
With a vitrectomy, tiny incisions are made in the eye and with a special probe, and the vitreous gel is cut out. It’s then replaced with saline or a gas bubble which is gradually replaced by the eye’s own fluids.
It is generally recommended to those who have PVD and are greatly troubled by the floaters, to leave it for several months and see if they disappear on their own. Otherwise, treatment options can be considered. A surgical solution can improve symptoms significantly.
When to see a retinal specialist
Mild floaters in the vision are normal. However, if there are new ones or bigger ones or flashes of light that you have not seen before, it could be the sign of a vitreous detachment or retinal detachment.
There are three major warning signs to remember:
1. New floaters that you haven’t seen before or a lot of floaters like a shower of pepper coming into your vision.
2. Bright flashes like electricity or flashbulbs probably in the side vision that are more than just an instant and not going away.
3. A curtain covering over the visual field.
If you notice any of these symptoms it could be a retinal problem and you should a retinal specialist ASAP.