Northeast Wisconsin Retina Associates



Any explanation regarding the symptoms of flashes and floaters or the process of retinal tear formation and retinal detachment must begin with a basic understanding of ocular anatomy (see Anatomy and Function of the Eye) and specifically, some knowledge regarding the vitreous – the clear gel which fills the main cavity within the eye. The vitreous is composed primarily of water and collagen fibers. When we are younger, the vitreous is more viscous – somewhat like gelatin or a partially cooked egg white.

As part of the aging process, the vitreous undergoes a gradual process of liquefication. As this occurs, collagen fibers within the vitreous tend to coalesce or clump together. These translucencies are suspended within the vitreous and cast shadows upon the retina as light passes through the eye cavity. Since one perceives the shadows which are cast, floaters appear as dark specks, cobwebs or veils. Such floaters are often considerably more noticeable in brighter illumination conditions or when looking at lightly colored, uniform backgrounds (such as the blue sky). Due to the liquefication process of the vitreous, these translucencies tend to move or “float” with eye or head movements. Typical floaters of this type are usually harmless.


The back surface of the vitreous is adherent to the retina and has a membranous quality much like the membrane found inside an eggshell. During mid to late adulthood, an abrupt process of shrinkage/contraction of this membrane occurs. This is called posterior vitreous detachment (PVD) or posterior vitreous separation. Posterior vitreous detachment is a normal part of the aging process of the eye and causes no problems with vision. Typically, this process occurs during the sixties or seventies. In some patients (particularly those who are nearsighted or who have had cataract surgery) this may occur quite a bit sooner – during the forties or fifties. In many cases, PVD may run its course uneventfully without causing any noticeable symptoms. The presence of this normal change can be detected at the time of future examinations however. In other cases, the typical symptoms of flashes and floaters develop. In a minority of patients, this can lead to serious problems – retinal tear formation and retinal detachment.

artist rendering: Posterior vitreous detachment

Posterior vitreous detachment

When symptomatic, posterior vitreous detachment can cause the sudden development of a few or even many new floaters in the vision AND/OR the abrupt onset of flashes of light in the peripheral vision. As described above, most floaters are caused by the coalescence of collegen fibers within the vitreous. Occasionally, as PVD occurs, the vitreous may pull on a blood vessel of the retina causing bleeding into the vitreous (vitreous hemorrhage). This may create more numerous and prominent floaters, as well as blurring of vision. The perception of flashing lights is caused by the vitreous tugging on the retina as the process of vitreous separation (PVD) occurs. The mechanical stimulation created by this tractional force results in the visual perception of light flashes. Usually, these symptoms will gradually diminish in prominence over several weeks or months. After this process occurs however, most individuals will continue to notice at least a few new floaters which were not present prior. Although such floaters may be somewhat annoying at times, they are not harmful and intervention for floaters alone is only rarely warranted.

In a minority of patients, the onset of the symptoms associated with PVD can indicate the development of serious abnormalities – namely retinal tear formation which can subsequently lead to retinal detachment (detailed below). Based on this concern, patients who develop the symptoms characteristic of PVD should seek prompt evaluation by their primary eye care provider.


As explained in the previous paragraph, occasionally the symptoms of PVD can indicate the development of a serious problem – retinal tear formation. In these cases, the vitreous is too adherent to the retinal surface in one or more places and the tractional force exerted can cause defects (tears) to form in the retinal tissue. The following factors increase the risk for development of retinal tears (and therefore retinal detachment):

Retinal detachment animation

Retinal detachment

  • nearsightedness (myopia)
  • previous cataract surgery
  • previous YAG laser surgery for secondary cataract
  • history of retinal tears/detachment in the other eye
  • family history of retinal detachment
  • previous significant eye trauma
  • presence of structurally weak areas in the retina (lattice degeneration)

Retinal Detachment Sequence

  • retinal detachment: vitreous pulls on retina

    Vitreous pulls on retina

  • retinal detachment: retina tears

    Retina tears

  • retinal detachment: vitreal fluid flows behind retina

    Vitreal fluid flows behind retina

  • retinal detachment: retina detaches further

    Retina detaches further

Enlarged retinal detachment images

If retinal tear(s) formation occurs, treatment with laser photocoagulation or cryotherapy is indicated promptly in the hopes of sealing the defect(s) and preventing progression to retinal detachment. Treatment of this type is performed in the office setting.

retina displaying retinal tear

Retinal tear

Once a tear(s) is present in the retina, fluid from within the eye cavity may begin to pass through accumulating in space beneath the retina. The retina then begins to separate from the back of the eye wall. This is called retinal detachment. As retinal detachment develops, progressive loss of vision will occur. Since tears usually develop towards the front part of the eye, this is where detachment begins. Peripheral (side) vision is therefore initially affected. As the area of detachment progresses, the defect in the patient’s peripheral vision enlarges. If the macula (central region of the retina) becomes involved by the detachment, central vision will also be significantly affected.

retina displaying retinal detachment

Retinal detachment

Treatment of retinal detachment requires surgery, most commonly performed in the operating room. A variety of techniques can be utilized to repair retinal detachments. These are detailed in Surgical Procedures and include pneumatic retinopexy, scleral buckling and vitrectomy surgery. Surgery to repair any retinal detachment is individualized and the exact details of your case are discussed by your retinal surgeon.

Most retinal detachments can be successfully repaired with a single operation. In a small percentage of patients, more than one procedure may be necessary particularly in cases where scar tissue formation occurs. An unrepaired retinal detachment will ultimately result in loss of useful vision.

With successful retinal reattachment, normalization of peripheral vision occurs rapidly. If the detachment has involved the macula, recovery of central vision is slow, gradual and variable. Improvement of the central vision occurs over the first several months following surgical repair and although recovery may be dramatic, it is seldom completely back to normal.

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