Gas Tamponade for Prevention of Postoperative Vitreous Hemorrhage in Diabetics

Inclusion: 1. The patient has medically-managed type I or II diabetes mellitus. 2. The age of the patient is \> 18 years old, 3. Snellen best-corrected visual acuity is from 20/40 to hand motions at one foot in the subject's study eye 4. Proliferative diabetic retinopathy with a clinically evident vitreous hemorrhage of duration of at least one month by subjective history is present in the subject's study eye. 5. The vitreous hemorrhage is symptomatic and primarily responsible for the patient's reduced vision in the judgement of the examiner. 6. Grade 0 or I vitreoretinal adhesion according to the classification system described by Ahn et al \[@\] in the study eye is clinically present. * Ahn J, Woo SJ, Chung H, et al. The effect of adjunctive intravitreal bevacizumab for preventing postvitrectomy hemorrhage in proliferative diabetic retinopathy. Ophthalmology. 2011; 118: 2218-2226. Exclusion: 1. The subject's study eye previously underwent anterior or posterior vitrectomy. 2. A lens or cornea opacity is thought to be responsible for two or more lines of reduced visual acuity in the subject's study eye (cataract, corneal scar, ectasia, etc.). 3. Optic nerve or retina disease otherwise not related to diabetes mellitus is thought to be responsible for two or more lines of reduced visual acuity in the subject's study eye (optic neuritis, macular degeneration, glaucoma, epiretinal membrane, etc.). 4. A non-ocular cause (i.e. cerebrovascular accident) or amblyopia is thought to be responsible for two or more lines of reduced visual acuity in the subject's study eye 5. Neovascular glaucoma with a high intraocular pressure ( \> 30 mm Hg) is discovered in the subject's study eye. 6. Medically uncontrolled systemic hypertension (systolic \> 200 mmHg or diastolic \> 120 mmHg) is present.