The purpose of this study is to assess the efficacy of intravitreous injections of Vitrase to induce posterior vitreous detachment(PVD) in subjects with moderate to severe non-proliferative diabetic retinopathy.

Inclusion Criteria:

• Moderately severe to severe non-proliferative diabetic retinopathy
• Best Corrected Visual Acuity (BCVA) in Early Treatment Diabetic Retinopathy Study (ETDRS) with pinhole of 20/320 or better in study eye & 20/50 or better in non-study eye.

Exclusion Criteria:

• Contraindications or hypersensitivities to Vitrase or anesthesia
• Any significant illness that could be expected to interfere with trial
• Prior Vitrase therapy
• Either a past diagnosis of clinically significant macular edema (CME) in study eye that required treatment or current CME that may require focal laser treatment within the next 30 days
• For either eye: ongoing ocular infection, inflammation or history of herpetic corneal lesion; an intravitreous injection within 30 days; glaucoma; intraocular pressure (IOP) of less than 5mmHg; retinal detachment or ocular tumors
• For study eye: vascular occlusive disease of fundus; corneal, lenticular or ocular media abnormalities; a significant ocular trauma within 6 months; previous vitrectomy; any prior laser treatment, cryo-retinopexy or any intraocular surgery; either a partial or complete posterior vitreous detachment (PVD); myopia of 6 or more spherical diopters and/or axial length exceeding 26mm; significant retinal pathology