A posterior vitreous detachment (PVD) is a condition of the eye in which the

vitreous membrane The vitreous membrane (or hyaloid membrane or vitreous cortex) is a layer of collagen separating the vitreous humour from the rest of the eye. At least two parts have been identified anatomically. The posterior hyaloid membrane separates the rear ...

separates from the

retina The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which the ...

. It refers to the separation of the posterior hyaloid membrane from the retina anywhere posterior to the vitreous base (a 3–4 mm wide attachment to the

ora serrata The ora serrata is the serrated junction between the choroid and the ciliary body. This junction marks the transition from the simple, non-photosensitive area of the ciliary body to the complex, multi-layered, photosensitive region of the retina. ...

). The condition is common for older adults; 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.

Symptoms

When this occurs there is a characteristic pattern of symptoms: * Flashes of light (

photopsia Photopsia is the presence of perceived flashes of light in the field of vision. It is most commonly associated with: * posterior vitreous detachment * migraine aura ( ocular migraine / retinal migraine) * migraine aura without headache * scin ...

) * A sudden dramatic increase in the number of

floaters Floaters or eye floaters are sometimes visible deposits (e.g., the shadows of tiny structures of protein or other cell debris projected onto the retina) within the eye's vitreous humour ("the vitreous"), which is normally transparent, or between ...

* A ring of floaters or hairs just to the temporal side of the central vision As a posterior vitreous detachment proceeds, adherent vitreous membrane 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. 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. A Weiss ring can sometimes be seen with ophthalmoscopy as very strong indicator that vitreous detachment has occurred. This ring can remain free-floating for years after detachment.

Complications

The risk of

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 blin ...

is the greatest in the first 6 weeks following a vitreous detachment, but can occur over 3 months after the event. 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 tear 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 blin ...

s/detachment.

Causes

The

vitreous Vitreous may refer to: Materials * Glass, an amorphous solid material ** Vitreous enamel, a material made by fusing powdered glass to a substrate by firing * Vitreous lustre, a glassy luster or sheen on a mineral surface Biology * Vitreous bod ...

(Latin for "glassy") humor is a gel which fills the eye behind the

lens A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements ...

. Between it and the

is the

. With age the vitreous humor changes, shrinking and developing pockets of liquefaction, similar to the way a

gelatin Gelatin or gelatine (from la, gelatus meaning "stiff" or "frozen") is a translucent, colorless, flavorless food ingredient, commonly derived from collagen taken from animal body parts. It is brittle when dry and rubbery when moist. It may also ...

dessert shrinks and detaches from the edge of a pan. At some stage the vitreous membrane may peel away from the retina. This is usually a sudden event, but it may also occur slowly over months. Age and refractive error play a role in determining the onset of PVD in a healthy person. PVD is rare in

emmetropic Emmetropia is the state of vision in which a faraway object at infinity is in sharp focus with the ciliary muscle in a relaxed state. That condition of the normal eye is achieved when the refractive power of the cornea and eye lens and the a ...

people under the age of 40 years, and increases with age to 86% in the 90s. 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). People with

myopia Near-sightedness, also known as myopia and short-sightedness, is an eye disease where light focuses in front of, instead of on, the retina. As a result, distant objects appear blurry while close objects appear normal. Other symptoms may includ ...

(nearsightedness) greater than 6

diopters A dioptre (British spelling) or diopter (American spelling) is a unit of measurement with dimension of reciprocal length, equivalent to one reciprocal metre, 1 dioptre = 1 m−1. It is normally used to express the optical power of a lens or cu ...

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 or macular pucker is a disease of the eye in response to changes in the vitreous humor or more rarely, diabetes. Sometimes, as a result of immune system response to protect the retina, cells converge in the macular area as t ...

. PVD may also occur in cases of

cataract surgery Cataract surgery, also called lens replacement surgery, is the removal of the natural lens of the eye (also called "crystalline lens") that has developed an opacification, which is referred to as a cataract, and its replacement with an intra ...

, within weeks or months of the surgery. The vitreous membrane is more firmly attached to the retina

anteriorly Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

, at a structure called the vitreous base. The membrane does not normally detach from the vitreous base, although it can be detached with extreme trauma. However, the vitreous base may have an irregular posterior edge. When the edge is irregular, the forces of the vitreous membrane 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 membrane 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 Glia, also called glial cells (gliocytes) or neuroglia, are non-neuronal cells in the central nervous system (brain and spinal cord) and the peripheral nervous system that do not produce electrical impulses. They maintain homeostasis, form myel ...

s to enter the vitreous humor and proliferate to create a thin

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

. Trauma can be any form from a blunt force trauma to the face such as a boxer's

punch Punch commonly refers to: * Punch (combat), a strike made using the hand closed into a fist * Punch (drink), a wide assortment of drinks, non-alcoholic or alcoholic, generally containing fruit or fruit juice Punch may also refer to: Places * Pu ...

or even in some cases has been known to be from extremely vigorous coughing or blowing of the nose.

Diagnosis

Posterior Vitreous Detachment is diagnosed via dilated eye examination. For some patients the vitreous gel is extremely clear and so it can be hard to see the PVD. In these cases, additional imaging such as Optical Coherence Tomography (OCT) or ocular ultrasound are used.

Treatment

Therapy is not required or indicated in posterior vitreous detachment, unless there are associated

s, which need to be repaired. In absence of retinal tears, the usual progress is that the vitreous humor will continue to age and liquefy and floaters will usually become less and less noticeable, and eventually most symptoms will completely disappear. Prompt examination of patients experiencing vitreous humor floaters combined with expeditious treatment of any retinal tears has been suggested as the most effective means of preventing certain types of retinal detachments.

References

External links

{{Medical resources , DiseasesDB = 31271 , ICD10 = H43.81* (depends on eye) , ICD9 = 379.21 , ICDO = , OMIM = , MedlinePlus = , eMedicineSubj = , eMedicineTopic = , MeshID = Eye diseases