AIM: To evaluate the postoperative refractive prediction error (PE) and determine the factors that affect the refractive outcomes of combined pars plana vitrectomy (PPV) or silicone oil removal (SOR) with cataract surgery. METHODS: The study is a retrospective, case-series study. Totally 301 eyes of 301 patients undergoing combined PPV/SOR with cataract surgery were enrolled. Eligible individuals were separated into four groups according to their preoperative diagnoses: silicone oil-filled eyes after PPV (group 1), epiretinal membrane (group 2), macular hole (group 3), and primary retinal detachment (RD; group 4). The variables affecting postoperative refractive outcomes were analyzed, including age, gender, preoperative best-corrected visual acuity (BCVA), axial length (AL), keratometry average, anterior chamber depth (ACD), intraocular tamponade, and vitreoretinal pathology. The outcome measurements include the mean refractive PE and the proportions of eyes with a PE within ±0.50 diopter (D) and ±1.00 D. RESULTS: For all patients, the mean PE was -0.04±1.17 D, and 50.17% of patients (eyes) had a PE within ±0.50 D. There was a significant difference in refractive outcomes among the four groups (P=0.028), with RD (group 4) showing the least favorable refractive outcome. In multivariate regression analysis, only AL, vitreoretinal pathology, and ACD were strongly associated with PE (all P<0.01). Univariate analysis revealed that longer eyes (AL>26 mm) and a deeper ACD were correlated with hyperopic PE, and shorter eyes (AL<26 mm) and a shallower ACD were correlated with myopic PE. CONCLUSION: RD patients have the least favorable refractive outcome. AL, vitreoretinal pathology, and ACD are strongly associated with PE in the combined surgery. These three factors affect refractive outcomes and thus can be used to predict a better postoperative refractive outcome in clinical practice.