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Floaters

by Kathryn Colby, MD, PhD

Floaters are opacities that move across the visual field and do not correspond to external visual objects.

Pathophysiology

With aging, the vitreous humor can contract and separate from the retina. The age at which this change occurs varies but most often is between 50 and 75 yr. During this separation, the vitreous can intermittently tug on the retina. The mechanical traction stimulates the retina, which sends a signal that is perceived by the brain and interpreted as light. Complete separation of the vitreous leads to an increase in floaters, which may last for years.

However, traction on the retina may create a hole (retinal tear), and if fluid leaks behind the tear, the retina may detach. Retinal detachment may also be caused by other factors (eg, trauma, primary retinal disorders). Lightning-like flashes, common in retinal detachment, are called photopsias. Photopsias can also occur when rubbing the eyes or when looking around after awakening.

Etiology

The most common cause of vitreous floaters is

  • Idiopathic contraction of the vitreous humor

Less common causes are listed in Some Causes of Floaters.

Rare causes of floaters include intraocular tumors (eg, lymphoma) and vitritis (inflammation of the vitreous). Intraocular foreign bodies can cause floaters but usually manifest with other symptoms, such as loss of vision, eye pain, or redness.

Some Causes of Floaters

Cause

Suggestive Findings*

Diagnostic Approach

Benign disorders

Idiopathic vitreous floaters

Mild, stable floaters that come into the field of view intermittently and move as the eye moves

Often shaped like cells or strands

Translucent

May be more noticeable under certain lighting conditions (eg, in bright sunlight)

Normal vision

May occur in both eyes, although not synchronously

Normal eye examination

Clinical evaluation

Serious vitreous and retinal disorders

Retinal detachment

Sudden, spontaneous, continuous shower of lightning-like flashes (photopsias)

Curtain of vision loss moving across the visual field, visual field defect (usually peripheral)

Abnormal retinal examination (eg, detached retina appears as a pale billowing parachute)

Possible risk factors (eg, recent trauma, eye surgery, severe myopia)

Indirect ophthalmoscopy by an ophthalmologist after pupillary dilation

Retinal tear

Sudden, spontaneous photopsias

May occur in the periphery of the retina and may be visible only by indirect ophthalmoscopy

Indirect ophthalmoscopy by an ophthalmologist after pupillary dilation

Vitreous detachment

Increase in unilateral floaters over 1 wk–3 mo in patients with average age of 50–75 yr

Floaters that are cobweb-like

One large floater that moves in and out of central vision

Spontaneous photopsias

Indirect ophthalmoscopy by an ophthalmologist after pupillary dilation

Vitreous hemorrhage

History of proliferative diabetic retinopathy or trauma

Loss of vision that may affect entire visual field

Loss of red reflex

Indirect ophthalmoscopy by an ophthalmologist after pupillary dilation

Vitreous inflammation (eg, cytomegalovirus, Toxoplasma , or fungal chorioretinitis)

Pain

Loss of visual acuity

Loss of vision affecting the entire visual field

Retinal lesions (sometimes cotton-like) that do not conform to an arterial or a venous territory

Risk factors (eg, AIDS)

Decreased red reflex

May be bilateral

Evaluation and testing as directed by an ophthalmologist, based on suspected cause

Nonocular disorders

Ocular migraine

Bilateral, synchronous, flashing lights often zigzagging on the peripheral field for 10–20 min

Possible blurring of central vision

Possible headache after visual symptoms

Possible migraine history

Clinical evaluation

*Unilateral unless otherwise specified.

Evaluation

The most important goal is to identify serious vitreous and retinal disorders. If these disorders cannot be ruled out, patients should be examined by an ophthalmologist using an indirect ophthalmoscope after pupillary dilation. Recognizing ocular migraine is also helpful.

History

History of present illness should ascertain onset and duration of symptoms and the shape and volume of floaters, as well as whether they are unilateral or bilateral and whether they have been preceded by trauma. The patient should try to distinguish floaters from lightning-like flashes of light (as in photopsias) or jagged lines across the visual field (as in migraine). Important associated symptoms include loss of vision (and its distribution in the visual field) and eye pain.

Review of systems should seek symptoms of possible causes, such as headaches (ocular migraine) and eye redness (vitreous inflammation).

Past medical history should note diabetes (including diabetic retinopathy), migraine headaches, eye surgery, severe myopia, and any disorders that could affect the immune system (eg, AIDS).

Physical examination

Eye examination should be reasonably complete. Best corrected visual acuity is measured. The eyes are inspected for redness. Visual fields are assessed in all patients. However, recognition of visual field defects by bedside examination is very insensitive, so inability to show such a defect is not evidence that the patient has full visual fields. Extraocular movements and pupillary light responses are assessed. If patients have a red eye or eye pain, the corneas are examined under magnification after fluorescein staining, and slit-lamp examination is done if possible. Ocular pressure is measured (tonometry).

Ophthalmoscopy is the most important part of the examination; it is done after dilating the pupils. To dilate the pupils, the physician first makes sure to record pupillary size and light responses, then instills drops, usually 1 drop each of a short-acting α-adrenergic agonist (eg, 2.5% phenylephrine) and a cycloplegic (eg, 1% tropicamide or 1% cyclopentolate). The pupils are fully dilated about 20 min after these drops are instilled. Ophthalmoscopy is done by a nonophthalmologist using a direct ophthalmoscope. An ophthalmologist does indirect ophthalmoscopy, which provides a more complete view of the retina, particularly the periphery.

Red flags

The following findings are of particular concern:

  • Sudden increase in floaters

  • Photopsias

  • Loss of vision, diffuse or focal (visual field defect)

  • Recent eye surgery or eye trauma

  • Eye pain

  • Loss of red reflex

  • Abnormal retinal findings

Interpretation of findings

Retinal detachment is suggested by sudden increases in floaters, photopsias, or any of its other, more specific characteristics (eg, visual field defects, retinal abnormalities). Bilateral synchronous symptoms suggest ocular migraine, although patients often have difficulty deciphering the laterality of their symptoms (eg, they often interpret scintillating scotoma of the left field of both eyes as left-eyed). Loss of red reflex suggests opacification of the vitreous (eg, vitreous hemorrhage or inflammation), but it also can be caused by advanced cataracts. Loss of vision suggests a serious disorder causing dysfunction of the vitreous or retina.

Testing

Patients who require evaluation by an ophthalmologist may need testing. However, tests can be selected by or in conjunction with the ophthalmologist. For example, patients suspected of having chorioretinitis may require microbiologic testing.

Treatment

Idiopathic vitreous floaters require no treatment. Other disorders causing symptoms are treated.

Key Points

  • Floaters by themselves rarely indicate a serious disorder.

  • Patients with any abnormal findings on examination require ophthalmologic referral.

  • If floaters are accompanied by any other symptoms (eg, persistent flashing lights, visual deficit, sensation of a moving curtain of vision loss), patients require ophthalmologic referral, regardless of examination findings.

Resources In This Article

Drugs Mentioned In This Article

  • Drug Name
    Select Trade
  • MYDRIACYL, TROPICACYL
  • No US brand name
  • AKPENTOLATE, CYCLOGYL

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