Posterior vitreous detachment
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A posterior vitreous detachment (PVD) is a condition of the eye in which the vitreous humor separates from the retina.
The vitreous humor fills the eye 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. When this occurs there is a characteristic pattern of symptoms:
- flashes of light (photopsia)
- a sudden dramatic increase in the number of floaters
- a ring of floaters or hairs just to the temporal side of the central vision
- a slight feeling of heaviness in the eye sometimes accompanied by slight nausea similar to very mild shock
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. If enough traction occurs, the retina may tear. If a retinal vessel is torn, the leakage of blood into the vitreous cavity is often perceived as a "shower" of floaters. Vitreous fluid may seep under the tear, separating the retina from the back of the eye, creating a retinal detachment. 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[1]. 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.
[edit] References
- ^ Byer NE. "Natural history of posterior vitreous detachment with early management as the premier line of defense against retinal detachment." Ophthalmology. 1994 Sep;101(9):1503-13; discussion 1513-4. PMID 8090453.
