Posterior vitreous detachment
Encyclopedia
A posterior vitreous detachment (PVD) is a condition of the eye in which the vitreous humour
separates from the retina
.
Broadly speaking, the condition is common for older adults and over 75% of those over the age of 65 develop it. Although less common among people in their 40s or 50s, the condition is not rare for those individuals. Some research has found that the condition is more common among women.
behind the lens
. At birth it is attached to the retina
. Over time the vitreous changes, shrinking and developing pockets of liquefaction, similar to the way a gelatin
dessert shrinks, or detaches, from the edge of a pan over time. At some stage the vitreous may peel away from the retina. This is usually a sudden event, but may also occur slowly over months.
Several studies have found a broad range of incidence of PVD, from 20% of autopsy cases to 57% in a more elderly population of patients (average age was 83.4 years). Age and refractive error play a role in determining the onset of PVD in a healthy person. PVD is rare in emmetropic people under the age of 40 years, and increases with age to 86% in the 90s.
People with myopia
(nearsightedness) greater than 6 diopters are at higher risk of PVD at all ages.
Posterior vitreous detachment does not directly threaten vision. Even so, it is of increasing interest because the interaction between the vitreous body and the retina might play a decisive role in the development of major pathologic vitreoretinal conditions, such as epiretinal membrane
.
As a posterior vitreous detachment proceeds, adherent vitreous may pull on the retina. While there are no pain fibers in the retina, vitreous traction may stimulate the retina, with resultant flashes that can look like a perfect circle.
, within weeks or months of the surgery.
However, the vitreous base may have an irregular posterior edge. When the edge is irregular, the forces of the vitreous peeling off the retina can become concentrated at small posterior extensions of the vitreous base. Similarly, in some people with retinal lesions such as lattice retinal degeneration or chorio-retinal scars the vitreous may be abnormally adherent to the retina. If enough traction occurs the retina may tear at these points. If there are only small point tears, these can allow glial cell
s to enter the vitreous and proliferate to create a thin epiretinal membrane
that distorts vision. In more severe cases, vitreous fluid may seep under the tear, separating the retina from the back of the eye, creating a retinal detachment
. Trauma can be any form from a blunt force trauma to the face such as a boxer's punch
or even in some cases has been known to be from extremely vigorous blowing of the nose.
If a retinal vessel is torn, the leakage of blood into the vitreous cavity is often perceived as a "shower" of floaters. Retinal vessels may tear in association with a retinal tear, or occasionally without the retina being torn.
The risk of retinal detachment is greatest in the first 6 weeks following a vitreous detachment, but can occur over 3 months after the event.
Prompt examination of patients experiencing vitreous floaters combined with expeditious treatment of any retinal tears has been suggested as the most effective means of preventing certain types of retinal detachments. The risk of retinal tears and detachment associated with vitreous detachment is higher in patients with myopic retinal degeneration, lattice degeneration
, and a familial or personal history of previous retinal tears/detachment.
Vitreous humour
The vitreous humour or vitreous humor is the clear gel that fills the space between the lens and the retina of the eyeball of humans and other vertebrates...
separates from the retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
.
Broadly speaking, the condition is common for older adults and over 75% of those over the age of 65 develop it. Although less common among people in their 40s or 50s, the condition is not rare for those individuals. Some research has found that the condition is more common among women.
Causes
The vitreous (Latin="glassy") humour fills the eyeHuman eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
behind the lens
Lens (anatomy)
The crystalline lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. The lens, by changing shape, functions to change the focal distance of the eye so that it can focus on objects at various distances, thus allowing a...
. At birth it is attached to the retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
. Over time the vitreous changes, shrinking and developing pockets of liquefaction, similar to the way a gelatin
Gelatin
Gelatin is a translucent, colorless, brittle , flavorless solid substance, derived from the collagen inside animals' skin and bones. It is commonly used as a gelling agent in food, pharmaceuticals, photography, and cosmetic manufacturing. Substances containing gelatin or functioning in a similar...
dessert shrinks, or detaches, from the edge of a pan over time. At some stage the vitreous may peel away from the retina. This is usually a sudden event, but may also occur slowly over months.
Several studies have found a broad range of incidence of PVD, from 20% of autopsy cases to 57% in a more elderly population of patients (average age was 83.4 years). Age and refractive error play a role in determining the onset of PVD in a healthy person. PVD is rare in emmetropic people under the age of 40 years, and increases with age to 86% in the 90s.
People with myopia
Myopia
Myopia , "shortsightedness" ) is a refractive defect of the eye in which collimated light produces image focus in front of the retina under conditions of accommodation. In simpler terms, myopia is a condition of the eye where the light that comes in does not directly focus on the retina but in...
(nearsightedness) greater than 6 diopters are at higher risk of PVD at all ages.
Posterior vitreous detachment does not directly threaten vision. Even so, it is of increasing interest because the interaction between the vitreous body and the retina might play a decisive role in the development of major pathologic vitreoretinal conditions, such as epiretinal membrane
Epiretinal membrane
Epiretinal membrane is a disease of the eye in response to changes in the vitreous humor or more rarely, diabetes. It is also called macular pucker. Sometimes, as a result of immune system response to protect the retina, cells converge in the macular area as the vitreous ages and pulls away in...
.
Symptoms
When this occurs there is a characteristic pattern of symptoms:- Flashes of light (photopsiaPhotopsiaPhotopsia is the presence of perceived flashes of light. It is most commonly associated with posterior vitreous detachment, migraine with aura, migraine aura without headache, retinal break or detachment, occipital lobe infarction and sensory deprivation...
) - A sudden dramatic increase in the number of floaters
- A ring of floaters or hairs just to the temporalTemple (anatomy)Temple indicates the side of the head behind the eyes. The bone beneath is the temporal bone as well as part of the sphenoid bone.-Anatomy:Cladists classify land vertebrates based on the presence of an upper hole, a lower hole, both, or neither in the cover of dermal bone which formerly covered the...
side of the central vision
As a posterior vitreous detachment proceeds, adherent vitreous may pull on the retina. While there are no pain fibers in the retina, vitreous traction may stimulate the retina, with resultant flashes that can look like a perfect circle.
Presentation, associated conditions, and prognosis
The vitreous is more firmly attached to the retina anteriorly, at a structure called the vitreous base. The vitreous does not normally detach from the vitreous base, although it can be detached with extreme trauma. PVD may also occur in cases of cataract surgeryCataract surgery
Cataract surgery is the removal of the natural lens of the eye that has developed an opacification, which is referred to as a cataract. Metabolic changes of the crystalline lens fibers over time lead to the development of the cataract and loss of transparency, causing impairment or loss of vision...
, within weeks or months of the surgery.
However, the vitreous base may have an irregular posterior edge. When the edge is irregular, the forces of the vitreous peeling off the retina can become concentrated at small posterior extensions of the vitreous base. Similarly, in some people with retinal lesions such as lattice retinal degeneration or chorio-retinal scars the vitreous may be abnormally adherent to the retina. If enough traction occurs the retina may tear at these points. If there are only small point tears, these can allow glial cell
Glial cell
Glial cells, sometimes called neuroglia or simply glia , are non-neuronal cells that maintain homeostasis, form myelin, and provide support and protection for neurons in the brain, and for neurons in other parts of the nervous system such as in the autonomous nervous system...
s to enter the vitreous and proliferate to create a thin epiretinal membrane
Epiretinal membrane
Epiretinal membrane is a disease of the eye in response to changes in the vitreous humor or more rarely, diabetes. It is also called macular pucker. Sometimes, as a result of immune system response to protect the retina, cells converge in the macular area as the vitreous ages and pulls away in...
that distorts vision. In more severe cases, vitreous fluid may seep under the tear, separating the retina from the back of the eye, creating a retinal detachment
Retinal detachment
Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. Initial detachment may be localized, but without rapid treatment the entire retina may detach, leading to vision loss and blindness. It is a medical emergency.The retina is a...
. Trauma can be any form from a blunt force trauma to the face such as a boxer's punch
Punch (strike)
A punch is a striking blow with the fist. It is the most commonly used attack in hand to hand combat. It is used in some martial arts and combat sports, most notably boxing where it is the only type of technique allowed...
or even in some cases has been known to be from extremely vigorous blowing of the nose.
If a retinal vessel is torn, the leakage of blood into the vitreous cavity is often perceived as a "shower" of floaters. Retinal vessels may tear in association with a retinal tear, or occasionally without the retina being torn.
The risk of retinal detachment is greatest in the first 6 weeks following a vitreous detachment, but can occur over 3 months after the event.
Prompt examination of patients experiencing vitreous floaters combined with expeditious treatment of any retinal tears has been suggested as the most effective means of preventing certain types of retinal detachments. The risk of retinal tears and detachment associated with vitreous detachment is higher in patients with myopic retinal degeneration, lattice degeneration
Lattice degeneration
Lattice degeneration is a disease of the eye where peripheral retina becomes atrophic in a lattice pattern and may develop tears / breaks / holes, which may further progress to retinal detachment. It is an important cause of retinal detachment in young myopic individuals...
, and a familial or personal history of previous retinal tears/detachment.
See also
- Central serous retinopathyCentral serous retinopathyCentral serous retinopathy , also known as central serous chorioretinopathy , is an eye disease which causes visual impairment, often temporary, usually in one eye, mostly affecting males in the age group 20 to 50 but which may also affect women...
- List of eye diseases and disorders
- Epiretinal membraneEpiretinal membraneEpiretinal membrane is a disease of the eye in response to changes in the vitreous humor or more rarely, diabetes. It is also called macular pucker. Sometimes, as a result of immune system response to protect the retina, cells converge in the macular area as the vitreous ages and pulls away in...
- VitrectomyVitrectomyVitrectomy is a surgery to remove some or all of the vitreous humor from the eye. Anterior vitrectomy entails removing small portions of the vitreous from the front structures of the eye—often because these are tangled in an intraocular lens or other structures...