Rhegmatogenous retinal detachment (RRD) is a separation of neurosensory retina from the underlying retinal pigment epithelium. It is caused by retinal tears, which let fluid pass from the vitreous cavity to the subretinal space. Pars plana vitrectomy (PPV), scleral buckling surgery and pneumatic retinopexy are three accepted management strategies whose efficacy remains controversial. Pneumatic retinopexy is considered in a separate Cochrane Review. The primary objective of this review was to assess the efficacy of PPV versus scleral buckling for the treatment of simple RRD (primary RRD of any extension with up to two clock hours large break(s) regardless of their anterior/posterior localisation) in people with (phakia) or without (aphakia) a natural lens in the eye, or with an artificial lens (pseudophakia). A secondary objective was to assess any data on economic and quality-of-life measures. We searched CENTRAL, which contains the Cochrane Eyes and Vision Trials Register; MEDLINE; Embase; LILACS; the ISRCTN registry; ClinicalTrials.gov and the WHO ICTRP. The date of the search was 5 December 2018. We included randomised controlled trials (RCTs) comparing PPV versus scleral buckling surgery with at least three months of follow-up. We used standard Cochrane methodology. Two review authors independently extracted the data and study characteristics from the studies identified as eligible after initial screening. We considered the following outcomes: primary retinal reattachment, postoperative visual acuity, final anatomical success, recurrence of retinal detachment, number of interventions needed to achieve final anatomical success, quality of life and adverse effects. We assessed the certainty of evidence using GRADE. This review included 10 RCTs (1307 eyes of 1307 participants) from Europe, India, Iran, Japan and Mexico, which compared PPV and scleral buckling for RRD repair. Two of these 10 studies compared PPV combined with scleral buckling with scleral buckling alone (54 participants). All studies were high or unclear risk of bias on at least one domain. Five studies were funded by non-commercial sources, while the other five studies did not report source of funding.There was little or no difference in the proportion of participants who achieved retinal reattachment at least 3 months after the operation in the PPV group compared to those in the scleral buckling group (risk ratio (RR) 1.07, 95% confidence intervals (CI) 0.98 to 1.16; 9 RCTs, 1261 participants, low-certainty evidence). Approximately 67 in every 100 people treated with scleral buckling had retinal reattachment by 3 to 12 months. Treatment with PPV may result in 4 more people with retinal reattachment in every 100 people treated (95% confidence interval (CI) 2 fewer to 11 more).There was no evidence of any important difference in postoperative visual acuity between participants in the PPV group compared to those in the scleral buckling group (mean difference (MD) 0.00 logMAR, 95% CI -0.09 to 0.10, 6 RCTs, 1138 participants, low-certainty evidence).There was little or no difference in final anatomical success between participants in the PPV group and scleral buckling group (RR 1.01, 95% CI 0.99 to 1.04, 9 RCTs, 1235 participants, low-certainty evidence). There were 94 out of 100 people treated with control (scleral buckling) that achieved final anatomical success compared to 96 out of 100 in the PPV group.Retinal redetachment was reported in fewer participants in the PPV group compared to the scleral buckling group (RR 0.75 (95% CI 0.59 to 0.96, 9 RCTs, 1320 participants, low-certainty evidence). Approximately 28 in every 100 people treated with scleral buckling had retinal detachment by 3 to 36 months. Treatment with PPV may result in seven fewer people with retinal detachment in every 100 people treated (95% CI 1 to 11 fewer).Participants treated with PPV on average needed fewer interventions to achieve final anatomical success but the difference was small and data were skewed (MD -0.20, 95% CI -0.34 to -0.06, 2 RCTs, 682 participants, very low-certainty evidence).Very low-certainty evidence on quality of life suggested that more people in the PPV group were "satisfied with vision" compared with the scleral buckling group (RR 6.22, 95% CI 0.88 to 44.09, 1 RCT, 32 participants).All included studies reported adverse effects, however, it was not always clear whether they were reported as number of participants or number of adverse effects. Cataract development or progression was more prevalent in the PPV group (RR 1.71, 95% CI 1.45 to 2.01), choroidal detachment was more prevalent in the scleral buckling group (RR 0.19, 95% CI 0.06 to 0.65) and new/iatrogenic breaks were observed only in the PPV group (RR 8.21, 95% CI 1.91 to 35.21). Estimates of the relative frequency of other adverse effects, including postoperative proliferative vitreoretinopathy, postoperative increase in intraocular pressure, development of cystoid macular oedema, macular pucker and strabismus were imprecise. Evidence for adverse effects was low-certainty evidence. Low- or very low-certainty evidence indicates that there may be little or no difference between PPV and scleral buckling in terms of primary success rate, visual acuity gain and final anatomical success in treating primary RRD. Low-certainty evidence suggests that there may be less retinal redetachment in the PPV group. Some adverse events appeared to be more common in the PPV group, such as cataract progression and new iatrogenic breaks, whereas others were more commonly seen in the scleral buckling group such as choroidal detachment.