2. Posterior Vitreous Detachment (PVD) is a separation between
the posterior vitreous cortex and the neurosensory retina,
with the vitreous collapsing anteriorly towards the vitreous
base.
It is a natural change that occurs during adulthood, when the
vitreous gel that fills the eye separates from the retina, the
light-sensing nerve layer at the back of the eye.
3. Diagram of the vitreous cavity
during posterior vitreous
detachment.
4.
5. Pathophysiology
•The vitreous is strongly attached to the retina at the vitreous base, a
ring shaped area encircling the ora serrata (2mm anterior and 4mm
posterior to it). The vitreous is also adherent to the optic disc margin,
macula, main retinal vessels and some retinal lesions such as lattice
degeneration.
•The initial event is liquefaction and syneresis of the central vitreous. A
rupture develops in the posterior hyaloid (or vitreous cortex) through
which liquefied vitreous flows into the retrovitreous space, separating
the posterior hyaloid from the retina. It typically starts as a partial PVD
in the perifoveal region and is usually asymptomatic until it progresses
to the optic disc, when separation of the peripapillary glial tissue from
the optic nerve head occurs, usually with formation of a Weiss ring and
accompanying symptoms.
•Vitreous traction at sites of firm adhesion may result in a retinal tear
with or without subsequent rhegmatogenous retinal detachment.
6. Epidemiology
•Prevalence of PVD increases with age and with axial length of the
eye. PVD affects most eyes by the eighth decade of life. Age at onset
is generally in sixth to seventh decade and men and women appear
to be equally affected.
Risk factors
•PVD occurs earlier in myopic eyes, in eyes with inflammatory
disease and following blunt trauma or cataract surgery (especially
when there is surgical vitreous loss).
7. Risk factors for early PVD include:
•cataracts
•eye surgery
•diabetes
•injury to the eye
•nearsightedness
•PVD usually occurs in both eyes. If you
have a vitreous detachment in your left eye,
you might also experience a detachment in
your right eye.
8. Signs and symptoms
•Many patients do not present with acute symptoms when PVD
occurs.
•Presenting symptoms include entoptic phenomena such as
floaters and photopsias. Floaters are the most common complaint
and result from vitreous opacities such as blood, glial cells or
aggregated collagen fibers torn from the margin of the optic disc.
They move with vitreous displacement during eye movement and
scatter incident light, which casts a shadow on the retina that is
perceived as a grey structure resembling "hairs", "flies" or
"spiderwebs". Floaters may continue indefinitely although they
usually gradually diminish over time. Photopsias are caused by
physical stimulation of the retina from vitreoretinal traction. They
reportedly occur in 50% of symptomatic PVD and are usually
vertical and temporally located.
•An alteration in peripheral visual field may indicate a retinal
detachment.
9. •Flashes. These small flashes of light are comparable to “seeing stars”
after hitting your head. They can last a few seconds or minutes and
tend to stop, or occur less often, once detachment is complete.
•Floaters. These floating spots in your field of vision can resemble tiny
specks, dust, dots, or cobweb-like shadows. They typically occur in
the first few weeks of PVD and are most noticeable when looking at a
light surface, such as a white wall or the sky.
•Cobweb effect. You may begin to see the outer edge of the vitreous
as it separates from the retina. It can feel like you’re looking through a
cobweb. This is temporary and goes away once detachment is
complete.
10. Retinal detachment(RD)
Posterior vitreous
detachment (PVD)
Location
Attached to the optic disc at both
sides
Is not attached to the optic disc in a
complete PVD. In incomplete PVD,
one or both sides may be attached to
optic disc margin.
Shape
Thick folded membrane. May be
smooth.
Usually fine, smooth/folded
membrane. May be thick especially in
cases with neovascularization of
disc/fibrovascular proliferation
Amplitude of Echo 100% compared to choroid-sclera. Usually less than 100%
Persistence in low gain
(around 40-50 decibel)
Persists Disappears
After-movements limited good
Associated features
May have macrocysts
(hemorrhagic or non-
hemorrhagic), peripheral
membrane also have 100%
amplitude
Peripheral/anterior part of
membrane usually has <100% spike,
may be attached to the ocular coats
(retina) at areas other than disc (at
neovascularization of retina )
Usually avascular. The fibrovascular
proliferations with attached vitreous
11. Differential diagnosis
•Retinal detachment
•Asteroid hyalosis/Synchysis scintillans
•Vitreous syneresis
•Vitreous inflammation (infectious and
non infectious)
•Vitreous haemorrhage
•Vitreous amyloidosis
•Ocular large cell lymphoma
12. Diagnostic testing
Posterior vitreous detachment is usually diagnosed with a dilated eye examination. However, if
the vitreous gel is very clear, it may be hard to see the PVD without additional testing, such
as optical coherence tomography (OCT) or ocular ultrasound (see Figure 2).
Figure 2. Most
posterior vitreous
detachments can be
diagnosed with a
dilated eye exam.
However, OCT (A)
and B-scan
ultrasound (B) are
diagnostic tests that
can be helpful in
diagnosing PVD.
17. Posterior vitreous detachment. Notes: (A) Partial posterior vitreous detachment is seen on this
OCT image. (B) Complete posterior vitreous detachment is visible on the OCT image as a linear
reflectivity suspended above the retinal surface
18.
19. How does vitreous detachment affect vision?
Although a vitreous detachment does not threaten sight, once in
a while some of the vitreous fibers pull so hard on the retina that
they create a macular hole to or lead to a retinal detachment.
Both of these conditions are sight-threatening and should be
treated immediately.
If left untreated, a macular hole or detached retina can lead to
permanent vision loss in the affected eye. Those who experience
a sudden increase in floaters or an increase in flashes of light in
peripheral vision should have an eye care professional examine
their eyes as soon as possible.
20. Vertical OCT image of
the right eye shows
vitreous detachment
over the macula with
a small operculum.
There is irregularity
of the foveal contour
and discontinuity of
the outer foveal
signals (arrow). (b)
After 8 weeks,
vertical OCT scan
confirms the
presence of a full-
thickness macular
hole with thickening
of its edges.
21. Management
General treatment
Observation with strict retinal detachment precautions, and follow up exam to rule out
retinal breaks. Vitrectomy can be considered with non-clearing vitreous hemorrhage.
Medical therapy
There are no medical therapies recommended for a PVD.
Medical follow up
After the diagnosis of an acute PVD, a follow up dilated funds examination should be
performed approximately 1 month afterwards. It is possible for a new retinal tear or
retinal detachment to occur during this dynamic time in the life of the vitreous.
Surgery
There are no surgical indications for routine PVDs. If a partial PVD is present that is
causing vitreomacular traction syndrome, pars plana vitrectomy with membrane
peeling may be indicated.
Surgical follow up
If surgery is performed, the recommended follow up intervals are day 1, week 1,
month 1 and month 3. Serial OCT scans are recommended to assess for anatomic
success and correlation with visual acuity outcomes.
Complications
PVDs are occasionally associated with vitreous hemorrhage, retinal tear and retinal
detachment. These should be ruled out during dilated fundus examination of patients
with a PVD.
