Vitreous Floaters

Etiology

The etiology of a vitreous floater or PVD is due to vitreous syneresis (liquefaction) and contraction with age. Additionally, trauma or injury to the globe can cause vitreous floaters.

Epidemiology

A vitreous detachment typically affects patients older than 50 and increases in prevalence by age 80. Individuals who are myopic or nearsighted have an increased risk of vitreous floaters. Additionally, eyes with an inflammatory disease after direct trauma to the globe or having recently undergone eye surgery have an increased chance of developing a vitreous floater. Men and women appear to be affected equally.[3][4][5][6]

Pathophysiology

The eye has 3 chambers: the anterior chamber, the posterior chamber, and the vitreous chamber. The anterior chamber consists of ocular content behind the cornea. The posterior chamber consists of content from the iris to the anterior aspect of the lens. The vitreous chamber consists of eye content behind the lens, which is the location of the vitreous floaters.

The vitreous gel, which consists of collagen fibers, fills the vitreous chamber, undergoing syneresis and contraction (shrinking) due to age and mechanical factors. Fibers are intertwined within the vitreous and attached to the retina's surface. Over time, the vitreous shrinks, and these fibers pull on the retinal surface. These fibers often break, allowing the vitreous to separate and continue shrinking. Eventually, the vitreous cannot fill the volume of its cavity. This separates the vitreous from the retina, creating vitreous floating in its chamber. If this process happens gradually, the symptoms are typically mild and can go unnoticed. Suppose the separation process is violent on an isolated portion of the retina, or abnormal adhesion exists between the vitreous and retina. In that case, the PVD can tear retinal vessels or the retina.

Histopathology

The vitreous comprises 99% water and a few type II and type IX collagen fibers with mucopolysaccharides and hyaluronic acid holding water within the vitreous. The vitreous is attached to the peripheral retina and pars plana. Additionally, it is attached to the macula, optic nerve, and vessels. The strongest attachment is at the vitreous base, while the weakest is along the retinal vessels. Thus, detachments and floaters are most common along the vessels and can lead to vitreous hemorrhage that coincides with the vitreous floater. Vitreoretinal junctions arise from the footplates of Muller’s cell at the internal limiting membrane.

History and Physical

Patients often report seeing floaters, bubbles, bugs, cobwebs, or dark spots that move during eye movement, which are most common with dim illumination and the temporal visual field. The displaced vitreous during eye movement scatters incoming light and casts a shadow on the retina that the patient perceives as a grey structure, such as hair, bugs, or webs. Photopsias are also reported due to the stimulation of the retina from vitreoretinal traction and pulling.

The work-up should include distinguishing retinal photopsia from visual changes associated with migraines, which can be associated with new floaters. Important questions should include: How long have these symptoms been occurring? Have these previously happened? Have there been recent eye surgeries? Does the family have a history of retinal detachment?

A slit lamp exam is needed to examine the anterior vitreous for pigmented cells (Shaffer sign), and indirect ophthalmoscopy with scleral indentation can rule out a retinal tear or break. Visualization of the PVD at the slit lamp with a 90-diopter lens can be done by identifying a gray-black strand floating in the vitreous. It can help to have the patient look up, down, and straight ahead to locate the floater. Shaffer's sign and vitreous hemorrhage increase the likelihood of a retina tear over a posterior vitreous detachment.

Evaluation

If the PVD cannot be viewed or a vitreous hemorrhage obscures the view, ultrasonography is indicated to rule out retinal detachments and to identify the PVD.

Treatment / Management

No treatment is indicated for a PVD or vitreous floater. If a retinal break is found, follow treatment guidelines for the break or tear.

The patient's management should include educating the patient on retinal detachment symptoms such as increased floaters, flashing lights, worsening vision, or the appearance of a curtain or shadow anywhere in the visual field. If these symptoms develop, immediate evaluation by an ophthalmologist is needed.

If no break or hemorrhage is found on examination, a repeat dilated exam with scleral depression needs to occur in 2 to 4 weeks. If no detachment is seen at 2 to 4 weeks, then repeat the dilated exam at 3 months and 6 months from the original onset of symptoms. If no retinal break is seen but mild vitreous or peripheral punctate retinal hemorrhages are present, a dilated exam must be performed in 1 week, 2 to 4 weeks, 3 months, and 6 months from the onset of symptoms. Suppose no retinal break is found, but significant vitreous hemorrhage or anterior pigmented vitreous cells are present. In that case, a retina specialist should perform a repeat examination the following day because of the high chance of a retinal break.

Differential Diagnosis

The differential diagnosis includes:

• Vitreous floater/posterior vitreous detachment
• Vitreous hemorrhage
• Retinal tear or detachment

Prognosis

Vitreous floaters or PVDs have a good prognosis. The prognosis is worse when a patient presents with vitreous hemorrhage or retinal detachments. Within 3 months, symptoms of the floater may subside. Some patient symptoms may not subside. If symptoms do not subside and greatly affect the patient's vision, an evaluation by a retinal specialist can be discussed.