METHODS: A prospective, randomized, controlled study. From October 2018 to June 2019, a total of 47 eyes of 47 patients with PDR were selected in the Department of Ophthalmology, People's Hospital of Guangxi Zhuang Autonomous Region. The patients were randomly divided into two groups: the patients who received IVC 2-3d before PPV as group A(26 eyes of 26 patients); and the patients who received IVC 7-8d before PPV as group B(21 eyes of 21 patients). The analysis included the operation time, the number of intraoperative bleeding, electrocoagulation, iatrogenic retinal tears, omental incision eyes, silicone oil-filled eyes. All patients were followed up 6mo, the best corrected visual acuity(BCVA)and the postoperative complications of the two groups were ducumented by the observers.

RESULTS: The BCVA measured 6mo after PPV were significantly better than that measured before PPV in both groups(P<0.05), there was no significant difference in BCVA between the two groups(1.37±0.83 vs 1.18±0.98, P>0.05). The average operation time of group A was lower than that of group B(73.19±22.78min vs 91.00±31.36min, P<0.05), there were no significant difference in the number of intraoperative bleeding, electrocoagulation, iatrogenic retinal tears, omental incision eyes, silicone oil-filled eyes between the two groups(P>0.05). One week after PPV, the incidence of high intraocular pressure in group B was higher than that in group A(group B: 43% vs group A: 15%, P<0.05). 6mo postoperative follow up, no recurrent vitreous hemorrhage occurred in either group, there were no significant difference in the incidence of secondary glaucoma and recurrent retinal detachment between the two groups(P>0.05).

CONCLUSION: PDR patients who received IVC 2-3d prior to PPV had shorter operation time than patients who received IVC 7-8d prior to PPV. Both groups can improve postoperative visual acuity, and the long-term clinical efficacy and safety are basically the same.