This study aimed to report anatomic and visual acuity outcomes and complications after 1000-centistoke silicone oil was used as a retinal tamponade for the treatment of complex retinal detachments. Prospective observational multicenter study conducted at community and university-based ophthalmology clinics. The study cohort consisted of 2439 patients (2573 eyes) treated for complex retinal detachments associated with cytomegalovirus (CMV) necrotizing retinitis or a non-CMV etiology, including proliferative diabetic retinopathy, giant retinal tears, proliferative vitreoretinopathy, or ocular trauma. Vitrectomy surgery was performed for complex retinal detachment with 1000-centistoke silicone oil as the retinal tamponade. Anatomic outcomes were complete retinal attachment and macular attachment. Visual acuity outcomes were ambulatory vision (> or = 4/200) and preservation of preoperative visual acuity. Complications were rates of secondary intraocular pressure elevation (> or = 30 mmHg), hypotony (< or = 5 mmHg), corneal opacification (including band keratopathy, corneal edema, and corneal abrasions), oil emulsification, and cataract. Outcomes were assessed 6, 12, and 24 months after surgery. At the 6-month examination, the retina was completely attached in 178 (78%) of 228 CMV eyes and in 855 (70%) of 1219 non-CMV eyes. The macula was attached in 216 (95%) of 228 and 1062 (89%) of 1189 CMV and non-CMV eyes, respectively. Ambulatory vision was noted in 151 (65%) of 234 CMV eyes and in 480 (38%) of 1251 non-CMV eyes. Visual acuity was preserved in 106 (46%) of 230 and 1035 (84%) of 1229 CMV and non-CMV eyes, respectively. The corresponding rates of complications for CMV and non-CMV eyes were: elevated intraocular pressure, 0 (0%) of 196 and 35 (3%) of 1196; hypotony, 11 (6%) of 196 and 228 (19%) of 1196; corneal opacity, 13 (6%) of 229 and 326 (26%) of 1248; emulsification, 3 (1%) of 211 and 29 (3%) of 959; and cataract in phakic eyes, 118 (64%) of 185 and 50 (63%) of 80. Retinal reattachment was achieved in the majority of eyes using vitrectomy and silicone oil retinal tamponade. Complication rates generally were less frequent in CMV eyes, but follow-up was shorter in this group of patients, largely because of reduced life expectancy. Cataract frequently developed in phakic eyes of study patients. Use of 1000-centistoke silicone oil can be considered in the management of complex retinal detachments associated with multiple etiologies.