Floaters

Presentation

Patients may present with a complaint of acute monocular floaters or flashes of light. Floaters can be described as gray or dark “blobs” or “worms” in the visual field and are caused by the interference of light moving through the vitreous ( Fig. 17.1 ). “Flashes” are flashes of white light caused by traction on the retina from the shrinking of vitreous jelly. The most common cause of acute visual floaters is a posterior vitreous detachment. The incidence of posterior vitreous detachment increases with age as the vitreous liquifies, shrinks, and contracts over time. The resulting traction and change in vitreous contour can cause the appearance of floaters and flashes. The differential diagnoses to consider are a retinal detachment, retinal tear, vitreous hemorrhage, migraine with aura, and cerebrovascular causes.

A migraine aura involves usually binocular rather than monocular visual changes that are typical of a primary ocular problem. More rarely occipital strokes can cause visual changes, but this is generally also binocular. In a patient with a transient monocular vision loss with vascular risk factors or symptoms of giant cell arteritis, amaurosis fugax should be considered. A retinal tear or detachment often causes visual impairment but should not be transient. A full retinal tear usually presents with partial monocular loss of visual field described as a “shadow” or “dark curtain.” A retinal detachment requires urgent referral to an ophthalmologist and is important to identify. A vitreous hemorrhage can present as monocular vision loss, dark streaks in the vision, or hazy vision. A posterior vitreous detachment, vitreous hemorrhage, and retinal detachment can sometimes be identified by bedside ultrasound.