What causes sudden onset of floaters?

Sudden onset of floaters—those small, shadowy shapes that drift across your field of vision—can be alarming and warrants prompt medical evaluation. While occasional, gradual increases in floaters are common with age-related vitreous liquefaction (vitreous syneresis) and posterior vitreous detachment (PVD), a sudden, dramatic appearance of new floaters—especially if accompanied by flashes of light (photopsia), a curtain-like shadow, or loss of peripheral vision—is a red flag for potentially serious intraocular pathology.

The most concerning cause is a retinal tear or detachment, which can occur when the aging vitreous pulls abnormally on the retina during PVD. Other possible causes include vitreous hemorrhage (e.g., from diabetic retinopathy, retinal vein occlusion, or trauma), uveitis (intraocular inflammation), or less commonly, retinal vasculitis or intraocular tumors. In rare cases, acute posterior vitreous detachment itself may cause transient symptoms without structural damage—but this diagnosis can only be confirmed after thorough dilated fundus examination.

Anyone experiencing sudden onset of floaters should seek urgent ophthalmologic assessment—ideally within 24 to 48 hours. A comprehensive eye exam will include pupillary dilation, slit-lamp biomicroscopy, and indirect ophthalmoscopy to evaluate the vitreous, retina, and optic nerve. Optical coherence tomography (OCT) or ocular ultrasound may be used adjunctively if media opacity limits visualization. Early detection and intervention—such as laser photocoagulation or cryopexy for retinal tears—can prevent progression to full-thickness retinal detachment and preserve vision.