What is posterior vitreous detachment?

Posterior vitreous detachment (PVD) is the separation of the back surface of the vitreous from the retina. It is mostly a benign process but it can be the precursor to more serious problems, retinal tear and detachment (see below). Many people notice flashing light and appearance of new floaters in their vision during PVD. The flashes are commonly described as resembling a lightening strike, sparkles, camera flash or strobe lights, and they are most often seen in the side vision towards the ear. The floaters can resemble black dots, cob webs, insects or squiggly lines, that often become fuzzy or cloudy with time.
 
Who is affected?
Posterior vitreous detachment usually occurs after the age of 50, but it can occur earlier. Short-sighted people develop PVD earlier and more frequently. Eye surgery (e.g., cataract extraction) and trauma can induce PVD. Around 80 % of the population can be expected to develop PVD by 75 years of age.
 
What causes posterior vitreous detachment and its symptoms?
The cavity inside the eye is filled with a gel-like substance called the vitreous. In youth, the vitreous is stuck to the surface of the retina. With aging, the vitreous shrinks and separates away from the retina. This posterior vitreous detachment occurs without any symptom in most people. Occasionally, the tug of the vitreous on the retina as it pulls away can be perceived as 'flashes'. The floaters represent condensations and debris in the vitreous, which have become mobile and more noticeable. The surface of the retina is full of blood vessels, and sometimes a small vessel can be torn during PVD and bleed into the eye cavity. In most cases, the bleeding is mild and resolves without problems.
 
How is posterior vitreous detachment diagnosed?
The detached vitreous is usually visible through the examination microscope. OCT scan may be performed for confirmation.  OCT scan uses computer-controlled laser beams to build cross-sectional images of the macula and nearby structures, offering unprecedented details of their anatomy. The ophthalmologist will perform a thorough examination of the entire retina, looking for possible damages sustained during PVD.
 
Does posterior vitreous detachment require treatment?
Posterior vitreous detachment is a normal process of aging and does not need to be treated. However, since PVD can lead to retinal tears and detachment, people who develop flashes and floaters in their vision need to undergo a thorough retinal examination as soon as possible. People who recently developed PVD may be asked to return for further examination because the process can take weeks or months to complete. Although floaters become less noticeable over time, some floaters will remain permanently. In a small proportion of people, the floaters can obscure the line of sight and become intolerable. Vitrectomy and YAG laser vitreolysis can be considered for intractable floaters but it is uncommon for people to require intervention for floaters.
 
What symptoms should be reported after the examination?
Flashes usually become less frequent or disappear altogether after their initial appearance.  If they worsen, or their character changes, you should report it immediately. The floaters do not disappear completely, but they do become less distinct with time. If new floaters appear, they should be reported without delay, even if you have been examined before. Long standing floaters do not pose a threat to vision and can be discussed during a routine consultation with your optometrist or ophthalmologist. Blurring of vision, dark shadows, blind spots or distorted vision are strong indications that the retina has been torn or detached. You must contact your eye doctor immediately, or go straight to the eye hospital emergency department, if the doctor cannot be reached.