Functional and structural outcomes and complications after pars plana vitrectomy for severe features of proliferative diabetic retinopathy in type 1 and type 2 diabetes mellitus

PURPOSE: To evaluate the functional and structural outcomes as well as postoperative complications after pars plana vitrectomy (PPV) for severe features of proliferative diabetic retinopathy (PDR) in type 1 and type 2 diabetes mellitus (DM) patients. METHODS: Twenty two eyes of type 1 diabetics (DM1 group) and 27 eyes of type 2 diabetics (DM2 group) were included. Best corrected visual acuity (BCVA), intraocular pressure (IOP), postoperative structural changes in optical coherence tomography (OCT) and postoperative complications such as recurrent vitreous haemorrhage, diabetic macular oedema, secondary glaucoma and persistent tractional retinal detachment (TRD) were assessed and compared between the two groups. RESULTS: Complete reattachment of retina was achieved in 88.9% from the DM1 group and in 95.5% from the DM2 group and remained attached in follow-up. BCVA in DM2 group was significantly lower preoperatively (p = 0.04). Mean postoperative BCVA significantly improved in both studied groups, but it was more evident in eyes of type 2 diabetics compared to type 1 diabetics. In eyes in the DM1 group there was perceptible stabilisation of BCVA. Poor visual acuity or lack of improvement in BCVA in the DM1 group was related to preoperative subretinal haemorrhage in macular region, and TRD involving macula, whereas in the DM2 group–to preoperative subretinal haemorrhage and neovascular glaucoma. The postoperative structural changes (disruption of EZ and ELM) were observed more often in DM2 group, but had the greatest impact on BCVA in eyes of type 1 DM. Complications after PPV for PDR were rare and hadn’t a significant influence on the final functional outcomes in both groups. CONCLUSIONS: Functional improvement after PPV for severe features of proliferative diabetic retinopathy were more noticeable in patients with type 2 DM. Postoperative structural changes had more negative impact on BCVA in type 1 diabetics.