Doctor's Notes on Eye Floaters
Floaters are small obstructions in the visual field of one or both eyes which resemble anything from black spots, strands to dust particles. Many people experience floaters; in most individuals floaters don’t cause any serious condition. Signs and symptoms of floaters are the appearance of black or dark spots, strands or dark material resembling cobwebs or “insects” wiggling or moving in their field of vision. A variation of floaters termed asteroid hyalosis describes many (dozens to hundreds) small yellowish
There are two main causes of floaters, benign and pathological. Benign causes are when, for example, tiny hemorrhages place blood and/or the blood’s contents into the eye’s vitreous gel. These usually resolve spontaneously. Pathological causes can be of several types including retinal tears and/or detachments, eye trauma, eye surgery, degenerative retinal conditions associated with diseases (for example, diabetes, blood disorders of clotting or bleeding, inflammatory diseases like rheumatoid arthritis and ocular diseases like cataracts. Infrequently, there may be other causes like retained foreign bodies, hemorrhagic macular degeneration and relatively rare parasitic infections.
Eye Floaters Symptoms
Patients may describe a wide variety of symptoms, including spiders or insects darting across their vision, cobwebs, dirt on the windshield, spots, strands, black spots in their vision, squiggly lines, and of course, floaters. There is a wide variety of presentations. Floaters are generally more noticeable to patients in bright lighting conditions such as outdoor activity or brightly illuminated computer screens, binoculars, or microscopes. This is because the bright illumination increases the contrast between the darkness of the floater and the surrounding light, making the floaters more apparent. Floaters generally jiggle or move when the eye moves. This is because the vitreous gel is a dynamic structure and compresses slightly with eye movements. Thus, when the patient looks to the right for example, the floater may first dart to the right and then re-center as the vitreous gel returns to its normal resting position.
Patients with other conditions causing some loss of vision, such as cataract or macular degeneration, may not notice their floaters as much. Some patients with large or numerous floaters upon examination may have few complaints and minimize their symptoms. One fascinating condition known as asteroid hyalosis is characterized by dozens or even hundreds of small yellowish floaters throughout the vitreous cavity in one or both eyes. Patients with asteroid hyalosis are often remarkably unaware or unperturbed by their vitreous opacities. Other patients with demanding jobs or hobbies, such as professional truck drivers or outdoor athletes, may have more complaints and the presence of floaters may have a more profound impact upon their daily living.
Eye Floaters Causes
Pathologic etiology: Similarly, the anterior vitreous attachment or vitreous base in toward the front of the eye can exert tractional forces on the underlying peripheral retina. A similar cascade of events can occur as seen posteriorly or in the back of the eye. However, anterior vitreous traction will usually not result in a separation or detachment of the vitreous, since the attachment of the vitreous to the underlying retina at the vitreous base is much stronger. This vitreo-retinal traction may pull on the thin anterior retinal tissues strongly enough to create a small hole in the retina. These holes are often associated with a flap of elevated retina still attached to the vitreous base. These holes often create a horseshoe shape around the elevated flap of retinal tissue. These peripheral retinal holes may cause a small amount of blood to escape into the vitreous cavity, which to the patient looks exactly like a benign posterior detachment floater. These small anterior vitreous hemorrhages produce unmistakable signs for the examining eye doctor and frequently necessitate a punctual repair of the retinal hole.
Left unattended, an anterior retinal hole or horseshoe tear can allow vitreous cavity fluid to accumulate under the retina. As this fluid progresses into the retinal tissues surrounding the hole, a retinal detachment can occur. This serious complication may require major surgery to restore the retina to its normal attached configuration. Left to its own devices, a retinal detachment can lead to certain blindness. Some patients are more at risk for anterior retinal hole formation and subsequent detachment. These patients include those with previous eye trauma or injury, previous eye surgery, high myopia or nearsightedness beyond 6 diopters, certain degenerative retinal conditions, diabetes, bleeding or clotting disorders, some systemic inflammatory diseases such as rheumatoid arthritis, and patients with other ocular diseases such as glaucoma.
Bleeding into the vitreous cavity may also result from conditions other than anterior retinal holes. The most common cause of vitreous hemorrhage is proliferative diabetic retinopathy, or PDR. This condition usually follows a long course of poorly controlled diabetes which allows abnormal blood vessels to grow in the retina. Eventually when left undetected or untreated, these abnormal fragile vessels actually grow into the vitreous cavity and bleed spontaneously. PDR must be treated by a qualified ophthalmologist with a wide variety of sophisticated measures, including injections, lasers, and surgery. Untreated PDR inevitably leads to blinding complications. A diabetic vitreous hemorrhage may absorb or regress of its own accord, or remain persistently in the vitreous cavity, obscuring the view of the abnormal underlying retina. Persistent vitreous hemorrhage may necessitate surgical removal by a technique called pars plana vitrectomy (PPV) or simply vitrectomy. This advanced procedure is accomplished by a vitreo-retinal surgeon using an operating microscope and 3 microincisions into the vitreous cavity through the pars plana. The pars plana is a circular band of tissue about 3 to 4 millimeters behind the cornea. Because the pars plana contains no major blood vessels and no retinal tissue, safe access is available to the surgeon.
A number of other conditions can less commonly produce vitreous floaters, including hemorrhagic macular degeneration, retained foreign bodies, postoperative matter, or rare parasitic infections, more common in third-world nations.
There are two categories of eye floater causes or etiology: benign and pathological. The benign category is by far the most common, while the possibility of a pathologic cause must be evaluated by an eye-care professional, such as your ophthalmologist or optometrist.
Benign etiology: The vitreous gel occupies the bulk of the interior of the eye, containing approximately 5 cc or milliliters of clear jelly. The vitreous gel performs no essential functions other than to occupy a space and to clearly transmit light from the cornea and lens in the front of the eye to the retina in the back of the eye. The gel itself is merely a vestige or non-functioning remnant of embryogenesis, or fetal development of the eye. During the very early stages of embryogenesis, the central cavity of the eye contains blood vessels vital to the normal development of the eye structures. These vessels form during the first trimester of pregnancy. By the end of the second trimester, the vitreous cavity vessels shrink or regress, then disappear completely. The remaining vitreous gel consists of 99% water and 1% protein and resembles clear Jell-O.
The vitreous gel is normally attached to the wall of the eye in two places: the optic nerve head and the front or anterior edge of the retina toward the front of the eye cavity. In many people, these attachments remain in place throughout life, but separation from these vitreous attachments are extremely common. A vitreous separation may occur for any number of reasons, including trauma or injury to the eye, routine ocular surgery, strenuous athletic activity, or simply for no obvious reason at all. Spontaneous vitreous separation from its normal attachment to the optic nerve, in fact, is the most common cause of vitreous or eye floaters.
When the vitreous gel separates from the optic nerve head in the back of the eye, it is termed a vitreous separation, a vitreous detachment, or a posterior vitreous detachment, usually abbreviated PVD. After the posterior attachment separates from the optic nerve, the vitreous, now free to move around within the eye, may bump into or touch the retina, causing flashes or photopsias. Once the separation or detachment process has completed and the entire back face of the gel is removed from the optic nerve attachment, the flashes generally stop. At this juncture, the now collapsed posterior face of the jelly has become somewhat less transparent and it is these aggregations of protein that we call vitreous syneresis or floaters. Occasionally, a small wisp of blood may be seen on the optic nerve or in the vitreous just after the detachment has occurred. These tiny hemorrhages are generally benign and resolve spontaneously. Nevertheless, such a finding should be followed until full resolution by a qualified eye-care professional.
Benign eye floaters occur at all ages. Over half of humanity eventually develops an eye floater, syneresis or PVD. A traumatic birth delivery due to malpresentation, breech presentation, prolonged labor, inadequate birth canal, or forceps delivery may compress the very elastic eyes of the newborn and cause a benign vitreous separation. Benign floaters may occur with even normal vaginal delivery as well.
When it comes to signs of eye disease, Americans are blind to the facts. A recent survey showed that while nearly half (47%) of Americans worry more about going blind than losing their memory or their ability to walk or hear, almost 30% of those surveyed admitted to not getting their eyes checked.
The following slides take a look at some of the signs and symptoms of some of the most common eye diseases.
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.