Posterior vitreous detachment

Posterior vitreous detachment is a physical change that occurs when the gel that fills the eye separates from the retina.

Symptoms

• Floaters (moving blurry shadows that obstruct vision)
• Flashes (like fireworks, usually in peripheral vision)

These symptoms usually become less severe after several weeks. Most patients develop posterior vitreous detachment after the age of 60, once in each eye, and the condition is usually not eye-threatening, but occasionally affects vision more permanently in the event of complications, such as retinal detachment or epiretinal membrane.

Mild myopia in vision is normal, but a sudden increase is often the first symptom of posterior vitreous detachment.

During posterior vitreous detachment, myopia is often accompanied by flashes, which are more noticeable in dark environments. Most patients experience myopia and flashes during the first few weeks of a posterior vitreous detachment, but in some cases the symptoms are barely noticeable. If the posterior vitreous detachment is complicated by vitreous hemorrhage, retinal detachment, epichoroidal membrane, or macular hole, the flashes and myopia may be accompanied by reduced or distorted vision. Myopia is most bothersome when located near the center of vision and less bothersome when located in peripheral vision. They can look like spiders, dust, or a swarm of insects – or in the shape of a circle or oval, called a Weiss ring.

Causes

Over time, the gel that fills the eye liquefies and condenses (shrinks) due to age and related wear and tear. Eventually, it cannot fill the entire volume of the vitreous cavity of the eye (which remains the same size throughout adulthood), and so the gel separates from the retina at the back of the eye cavity.

Over the next 1 to 3 months, the vitreous thickens and the sides of the gel also separate from the retina until the posterior vitreous detachment is complete.

If the posterior vitreous detachment progresses gently, gradually, and evenly, symptoms are usually mild. However, if the separation forces are strong or concentrated in a specific part of the retina, or if there is an abnormal adhesion between the vitreous and the retina, the posterior vitreous detachment can cause a tear in the retina or a hemorrhage in a retinal blood vessel.

Risk factors

Posterior vitreous detachment is rare in people under 40 years of age and more common in older age.

Additional risk factors for posterior vitreous detachment include myopia, trauma, and recent eye surgery, such as cataract surgery. Patients who experience posterior vitreous detachment in one eye will often experience posterior vitreous detachment in the other eye within 1 year.

Diagnosis

Posterior vitreous detachment is usually diagnosed with fundoscopy. However, additional tests, such as optical coherence tomography (OCT) or ocular ultrasound, may be needed. 

Treatment and outcome

Posterior vitreous detachment usually has a good prognosis and symptoms resolve in the vast majority of patients. Most patients no longer experience flashes after 3 months and myopia tends to improve. No specific treatment is required for posterior vitreous detachment. Complications of posterior vitreous detachment are rare but can be serious and require emergency treatment, such as laser for retinal tears or surgery for retinal detachment. For this reason, one or more check-ups within 3 months of the onset of posterior vitreous detachment are recommended. In rare cases, floaters from posterior vitreous detachment persists and vitrectomy surgery may be required.