Refractive outcomes in eyes after vitrectomy vary as the timing of cataract surgery may influence the outcome when done as staged surgery after vitreoretinal (VR) surgery or at the same time as VR surgery. The authors aimed to determine the prediction error in the IOL power calculation using the SRK-II formula in children undergoing cataract surgery following pars plana vitrectomy (PPV). This was a retrospective review of 92 eyes of 90 patients. Twenty-four were excluded because of incomplete data, lack of follow-up and poor fundus visibility leaving 68 eyes of 66 children included for analysis: 64 unilateral and two bilateral. Mean age was 12.09 ±3.3 years, mean axial length of 24.85 ±1.9mm, calculated IOL power of 17.51 ±4.80D, IOL power implanted of 17.55 ±4.70D, postoperative spherical equivalent of -0.19 ±1.90D and absolute prediction error (APE) of 1.29 ±1.13D. APE was greater in the eyes of younger children (≤10 years), with average axial length (>22 to <24.5mm), with steeper corneas (K≥43.5), in those with silicone oil removal prior to cataract surgery and in the absence of scleral buckle and corneal suture. The authors defined desirable refractive outcome as a prediction error <0.50D and achieved this in 35%. The APE using the SRK II formula in this study was comparable to the reported literature for routine cataract surgery without PPV.