Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Diabetic Retinopathy ?
    ### Response:
    If you have a lot of blood in the center of the eye, or vitreous gel, you may need a vitrectomy to restore your sight. If you need vitrectomies in both eyes, they are usually done several weeks apart. A vitrectomy is performed under either local or general anesthesia.
    