Vitreous floaters are microscopic collagen fibers within the vitreous that tend to clump and cast shadows on the retina, appearing as floaters to the patient. The most common cause of vitreous floaters in ophthalmology is posterior vitreous detachment (PVD), a separation of the posterior hyaloid face from the retina. Often this condition is not visually threatening. Patients that present with signs and symptoms of vitreous floaters need to be evaluated by an ophthalmologist.
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.
A vitreous detachment typically affects patients older than the age of 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 have recently undergone eye surgery have an increased chance of developing a vitreous floater. Men and women appear to be affected equally.
There are three chambers in the eye: 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 and 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 are attached to the surface of the retina. Over time, the vitreous shrinks, and these fibers pull on the retinal surface. Often these fibers break and allow the vitreous to separate and continue shrinking. Eventually, the vitreous cannot fill the volume of the cavity it sits within. This leads to the separation of 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. If the process of separation is violent, on an isolated portion of the retina, or there is the presence of abnormal adhesion between the vitreous and retina, the PVD can tear retinal vessels or the retina itself.
The vitreous is composed of 99% water and a few type II and type IX collagen fibers with many 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 attachment 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.
Patients often will report seeing floaters, bubbles, bugs, cobwebs, or dark spots that move during eye movement that 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 also are 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 to consider should include: How long have these symptoms been occurring? Have these previously happened before now? 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 of 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.
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.
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 management of the patient should include educating the patient on retinal detachment symptoms such as the following: increase in 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 at 2 to 4 weeks, no detachment is seen, then repeat the dilated exam at three months and six months from the original onset of symptoms. If no retinal break is seen, but mild vitreous hemorrhage or peripheral punctate retinal hemorrhages are present, a dilated exam needs to be performed one week, 2 to 4 weeks, three months, and six months from the onset of symptoms. If no retinal break is found, but significant vitreous hemorrhage or anterior pigmented vitreous cells are present, repeat examination should be performed the following day by a retina specialist because of the high chance of a retinal break.
The differential diagnosis includes:
Vitreous floaters or PVDs have a good prognosis. Prognosis is worse when a patient presents with vitreous hemorrhage or retinal detachments. Within three months, symptoms of the floater will 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.
The greatest concern with vitreous floaters is the potential for related retinal pathology that is sight-threatening. Two examples are a macular hole or retinal detachment. These occur when the fibers in the vitreous do not break as it is shrinking and pull violently on the retina. If left untreated, both of these problems can lead to significant, permanent loss of sight.
It is best to be evaluated by an ophthalmologist urgently if vitreous floaters develop to minimize the risk of permanent vision loss.
Vitreous floaters is a benign condition, however, it is important to know that it can also be associated with retinal pathology. Vitreous floaters are microscopic collagen fibers within the vitreous that tend to clump and cast shadows on the retina, appearing as floaters to the patient. The most common cause of vitreous floaters in ophthalmology is posterior vitreous detachment (PVD), a separation of the posterior hyaloid face from the retina. Often this condition is not visually threatening. The initial evaluation is done by a primary care provider or optometrist. Patients that present with signs and symptoms of vitreous floaters need to be evaluated by an ophthalmologist. Ophthalmology nurses assist with the initial evaluation and patient education. [Level 5]
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