A vitrectomy is a surgical procedure to remove the vitreous (the gel at the center of the eye) when blood and buildup of scar tissue, or detachment of the retina, impair a patient’s vision. Removing this blockage restores transparency and allows light to travel to the retina. In many cases, this can significantly improve vision.

Blood and scar tissue are removed by making incisions in the sclera (the tough, white fibrous tissue covering the eye), then cutting and suctioning out the vitreous gel, which makes up about two-thirds of the eye’s volume.

Once the surgery occurs, a substance, usually a balanced salt solution, is inserted into the eye to replace the vitreous gel. This helps maintain the eye’s shape and restores normal pressure to the eye. As the eye heals over time it secretes aqueous and nutritive fluids, helping to replace the vitreous.

Vitrectomies are performed to:

• Clear the eye of blood and debris
• Remove scar tissue
• Alleviate strain on the retina 

The procedure is often necessary when symptoms related to these disorders become severe enough to obscure light as it passes through the vitreous to the retina. This blockage creates blurred vision for many patients. In some cases, the patient’s vision may be completely obscured.

Objects and substances that may be responsible for this blockage include:

• Blood
• Inflammatory cells
• Debris
• Scar tissue

The vitreous also may be removed when it pulls the retina from its normal position. This is known as a detached retina, and it can lead to permanent blindness if left untreated.

In people with diabetes, an eye disorder called diabetic retinopathy is the most common source of problems with the vitreous. This disease causes an abnormal growth of blood vessels in the retina. These vessels are weak and tend to hemorrhage blood into the vitreous. This blood and scar tissue combine to block the passage of light into the retina, which causes vision to become impaired or completely lost.  

Other conditions that affect the vitreous and can lead to a vitrectomy include:

• Macular hole. A hole in the macula, the tiny oval area made up of millions of nerve cells located at the center of the retina. The macula is the source of sharp, central vision.
  
  
• Preretinal membrane fibrosis (macular pucker). Scar tissue that has formed on the macula and obscures vision.
  
  
• Bleeding inside the eye (vitreous hemorrhage).
  
  
• Injury or infection.
  
  
• Certain problems related to previous eye surgery.

The success of vitrectomy varies. The earlier the surgery is performed for retinal detachments, the more likely it is to be successful. When the goal is to remove blood from the eye, the prognosis is excellent. However, vitrectomies performed to reattach a detached retina are successful only about half the time, according to the American Diabetes Association. In some patients with recent traction retinal detachment or vitreous hemorrhage, the procedure can restore vision, according to the U.S. Centers for Disease Control and Prevention (CDC).