5. The subject is determined to need a PPV because of reduced BCSVA principally from a non-clearing vitreous hemorrhage, TRD, fibrous proliferation, or a combination of the three. When non-clearing vitreous hemorrhage is the principal reason for PPV, the hemorrhage must have been present by subjective history for at least 3 months. When TRD is the principal reason for PPV, the TRD must be threatening (within one disc diameter) or involving the fovea. When fibrovascular proliferation is the principal reason for PPV, it must be extensive (>3 clock hours) and threatening (within one disc diameter) or involving the fovea.