What causes floaters in the eye?

What Causes Floaters in the Eye

Floaters in the eye are primarily caused by posterior vitreous detachment (PVD), which is a separation of the posterior vitreous cortex from the internal surface of the retina. 1 This natural age-related process typically occurs between ages 45 and 65, with men experiencing it earlier than women.

Main Causes of Floaters

1. Posterior Vitreous Detachment (PVD)

• Age-related vitreous liquefaction: As we age, the gel-like vitreous undergoes syneresis (liquefaction)
• Separation process: The vitreous gradually detaches from the retina, beginning posteriorly and progressing anteriorly
• Weiss ring formation: When the vitreous detaches from the optic nerve head, it creates a visible ring-shaped floater (Weiss ring) 1

2. Components of Floaters

Floaters may consist of:

• Condensations of vitreous collagen that clump together as the vitreous liquefies
• Blood from torn or avulsed retinal vessels during PVD
• Epipapillary glial tissue (Weiss ring) torn from the optic nerve head
• Pigmented cells in the vitreous, indicating possible retinal break 1

3. Risk Factors for Earlier PVD Development

• Myopia (nearsightedness)
• Trauma to the eye
• Prior ophthalmic surgical procedures
• Male gender (men develop PVD earlier than women) 1

Clinical Significance

Symptoms Associated with Floaters

• Visual perception: Spots, shadows, or cobweb-like structures in the visual field
• Movement: Floaters move with eye movement but lag slightly
• Light sensitivity: More noticeable against bright backgrounds
• Flashes (photopsias): Often accompany floaters during acute PVD, especially in dark environments 1, 2

Warning Signs

Floaters may indicate serious conditions requiring prompt evaluation:

• Sudden increase in number or size of floaters
• Floaters with flashes of light
• Vitreous hemorrhage: Blood in the vitreous significantly increases risk of retinal tears
• Shadow or curtain in peripheral vision (possible retinal detachment) 1

Complications and Associated Conditions

Retinal Tears and Detachment

• 8-22% of patients with acute PVD symptoms have a retinal tear at initial examination
• Direct correlation between amount of vitreous hemorrhage and likelihood of retinal tear
• 2-5% of patients without detected breaks at initial presentation may develop breaks in following weeks 1

Vitreomacular Traction (VMT)

• During PVD evolution, vitreous may remain adherent to the macula while detaching elsewhere
• This traction can cause macular thickening, distortion, cystoid changes, and even tractional detachment 1

Epiretinal Membrane (ERM)

• PVD can contribute to ERM formation
• ERMs may cause macular traction and similar visual symptoms to floaters 1

Management Considerations

Most floaters are benign and require only observation, but patients should be educated about warning signs requiring urgent evaluation:

• Sudden increase in floaters
• New flashes of light
• Loss of peripheral vision
• Decrease in visual acuity 1

For severely symptomatic patients with persistent floaters affecting quality of life, treatment options include:

• Pars plana vitrectomy: Most definitive treatment but carries risks of infection, cataract formation, and retinal detachment
• Nd:YAG vitreolysis: Less invasive alternative with variable success rates 2, 3

Key Takeaway

While floaters are often a normal age-related phenomenon caused by PVD, they can sometimes signal serious conditions like retinal tears or detachment. Any sudden increase in floaters, especially when accompanied by flashes or visual field defects, requires prompt ophthalmologic evaluation.