AIM: To investigate the rates of emulsification in silicone oil (SO) tamponades of differing viscosities used during pars plana vitrectomy (PPV) in the treatment of complicated vitreoretinal diseases. METHODS: This study was a prospective randomized clinical trial. Totally 290 cases with greater likelihoods of secondary detachment were included and randomly grouped into either Siluron 2000 (n=143) or Siluron 5000 (n=147) SO tamponades with 23-gauge PPV. Patient follow-ups and data analyses were conducted 1, 3, 6, and 12mo post-surgery. RESULTS: The time of the SO emulsification ranged from 1 to 17mo, with a mean of 7.3±4.2mo. The Siluron 5000 group showed a slower emulsification rate in comparison to the Siluron 2000 group. The Siluron 2000 group took a shorter time to show signs of emulsification, necessitating earlier SO removal. However, there were no significant differences in the occurrence of complications, including secondary retinal detachment, cataract, corneal abnormality, high intraocular pressure and hypotony. CONCLUSION: The Siluron 2000 SO tamponade shows a faster rate of emulsification than the Siluron 5000 SO, necessitating earlier removal. Both groups show similar results in terms of anatomical success and visual acuity outcome, and there is no significant difference between the SOs regarding the occurrence of complications.