Evaluation of Ranibizumab in Proliferative Diabetic Retinopathy (PDR) Requiring Vitrectomy

Inclusion Criteria: * Ability to provide written informed consent and comply with study assessments for the full duration of the study * Age \> 20 years * Best corrected visual acuity of 20/40 to 20/800 in the study eye * Very servere nonproliferative diabetic retinopathy (ETDRS level 53E) OR moderate proliferative diabetic retinopathy (ETDRS level 65) * Visual reduction attributable to diabetic vitreous hemorrhage or diabetic macular edema * Candidate for vitrectomy procedure Exclusion Criteria: * Pregnancy (positive Pregnancy test) or lactation * Premenopausal women not using adequate contraception. The following are considered effective means of contraception: surgical sterilization or use of oral contraceptives, barrier contraception with either a condom or diaphragm in conjunction with spermicidal gel, an IUD, or contraceptive hormone implant or patch. * Any other condition that the investigator believes would pose a significant hazard to the subject if the investigational therapy were initiated. * Participation in another simultaneous medical investigation or trial. * Visual impairment attributable to causes other than diabetic macular edema or diabetic vitreous hemorrhage. * Use of intraocular or periocular corticosteroids within 6 months. * History of panretinal photocoagulation * History of macular laser photocoagulation * History of pars plana vitrectomy * Prior or concomitant treatment with ranibizumab, bevacizumab, or pegaptanib sodium, either as part of an investigational study or as an off-label medication. * Current treatment of a systemic infection