OBJECTIVE To investigate whether intraocular silicone oil (SO) tamponade is associated with functional changes in patients with both macula-on and macula-off rhegmatogenous retinal detachments (RRDs). METHODS Prospective observational cohort study of patients with RRD treated by vitrectomy with gas or SO tamponade at the University Medical Center Utrecht. Outcome was best-corrected visual acuity (BCVA) and retinal sensitivity on microperimetry 2 months after surgery. RESULTS In total, 40 eyes were included. There are 10 eyes in each of the following groups: macula-on RRD and gas, macula-on RRD and SO, macula-off RRD and gas, and macula-off RRD and SO. Median retinal sensitivity on microperimetry was decreased following SO tamponade compared to gas tamponade for both macula-on and macula-off RRD (p < 0.037). CONCLUSIONS Foveal sensitivity was decreased in eyes after SO tamponade compared to gas tamponade. These effects were observed in patients with macula-on as well as macula-off RRD. Although further investigation is warranted to validate our results and to study underlying mechanisms, retinal surgeons need to be aware of these findings after the use of SO tamponade.