Background
The most common reason for loss of vision in patients with diabetes is swelling of the retina, also known as macular edema. When macular edema develops laser treatment is usually indicated. Laser treatment can often slow or stop the vision loss due to macular edema. Unfortunately, laser treatment is ineffective in some patients.

The eye is filled with a substance called the vitreous gel. In a diabetic it is possible for the vitreous gel to contract and cause macular edema. Macular edema caused by the vitreous gel irritating the retina is less likely to respond to standard laser treatment. Removing the vitreous gel can result in a reduction in macular edema and a stabilization or improvement in vision.

Evidence
Many small studies have shown that macular edema can be reduced by removing the vitreous gel from the eye. Reducing macular edema can result in stabilization or improvement in vision. In a study of 55 eyes which underwent vitrectomy for macular edema, 94% had significant resolution of their macular edema. The average vision before surgery was 20/160, and improved to 20/80 after the surgery.¹

Procedure
Vitrectomy is a surgical procedure in which the vitreous gel and any membraneous attachments to the retina are removed. A vitrectomy is performed under local anesthesia using the operating microscope. Microscopic forceps are used to grasp the membrane and peel it off the retinal surface.

Risks
Risks of the procedure include hemorrhage, infection, retinal detachment or cataract formation. Complications related to the underlying diabetic retinopathy may occur despite vitrectomy.

Comment
Vitrectomy is effective in reducing diabetic macular edema. For patients who have lost vision due to macular edema, and who do not respond well to laser treatment, vitrectomy may be a reasonable alternative to observation alone.