What causes eye floaters?

What Causes Eye Floaters?

Eye floaters are primarily caused by posterior vitreous detachment (PVD), an age-related process where the vitreous gel naturally separates from the retina, typically occurring between ages 45-65. 1

Primary Mechanisms

Age-Related Vitreous Changes:

• Vitreous syneresis is the fundamental age-related liquefaction of vitreous gel that causes condensation of collagen fibers, which then cast shadows on the retina that patients perceive as floaters 1, 2
• PVD accounts for approximately 83% of cases presenting with sudden onset floaters 3
• In patients 50 years or older, acute PVD is responsible for 95% of floater symptoms 3

Specific Anatomic Sources:

• Prepapillary glial tissue on the posterior hyaloid membrane is a primary cause of floaters in eyes with PVD 3
• In eyes without PVD, fiber-like opacities on plicated membranes of Cloquet's canal or associated with gel liquefaction cause symptoms 3

Sight-Threatening Causes Requiring Urgent Evaluation

Retinal Pathology:

• Retinal tears are present in 8-22% of patients with acute PVD symptoms at initial examination 1, 4
• Vitreous hemorrhage appears as a sudden shower of new floaters or "smoke" in vision, with direct correlation between hemorrhage amount and likelihood of retinal tear 1, 4
• Retinal detachment manifests as floaters accompanied by peripheral visual field loss 1, 2
• Vitreoretinal traction occurs when vitreous partially separates but remains adherent to portions of the macula, causing macular thickening and distortion 1

Secondary Causes

Systemic and Ocular Disease:

• Diabetic retinopathy can lead to vitreous hemorrhage causing floaters 1, 2
• Retinal vascular disease, including venous occlusions, contributes to floaters through associated epiretinal membrane formation 1
• Inflammatory eye diseases cause cellular debris accumulation in the vitreous 1, 2
• Trauma-related blunt or penetrating eye injuries can precipitate PVD, with symptoms appearing immediately or up to 6 weeks post-trauma 1

Critical Red Flags

Immediate ophthalmologic evaluation is mandatory when floaters present with:

• New-onset flashes of light (photopsias), indicating vitreoretinal traction 1, 4, 2
• Peripheral visual field loss, suggesting possible retinal detachment 1, 4, 2
• Sudden decrease in visual acuity 4
• Shower of new floaters or "smoke" appearance, indicating vitreous hemorrhage 1, 4

Important Clinical Pitfall

Even patients with initially normal examination have a 2-5% chance of developing retinal breaks within 6 weeks 1, 4. Approximately 80% of patients who later develop breaks had either pigmented cells, hemorrhage, or new symptoms prompting return visit 1, 4. Therefore, all patients with acute PVD symptoms require follow-up examination within 6 weeks, even if the initial examination is normal 1, 4.

Essential Examination Requirements

All patients with new floaters must undergo:

• Thorough peripheral fundus examination with scleral depression by an ophthalmologist skilled in binocular indirect ophthalmoscopy 1, 4
• Visual acuity measurement 1
• Vitreous evaluation for pigment, hemorrhage, or syneresis 1
• B-scan ultrasonography if media opacity or patient cooperation precludes adequate peripheral retina examination 4