Intraoperative Modified Peripheral Panretinal Photocoagulation in Proliferative Diabetic Retinopathy

This study aimed to compare the outcomes of intraoperative conventional panretinal photocoagulation (CPRP) with the modified peripheral panretinal photocoagulation (PPRP) technique in pars plana vitrectomy (PPV) in patients with proliferative diabetic retinopathy (PDR).

Sixty-three eyes of 56 patients with PDR were retrospectively studied. Patients with very severe proliferation were excluded in this study. Twenty-six patients (30 eyes) received CPRP and 30 patients (33 eyes) received modified PPRP in PPV. Preoperative and postoperative ophthalmologic examinations were performed. Best corrected visual acuity (BCVA) was performed at baseline and 3 months after surgery. Central macular thickness (CMT) was measured at 1 week and 3 months after surgery. Postoperative inflammation was examined at 1 day and 3 months after surgery. Other postoperative complications were also analyzed at 3 months after surgery.

Of all the included eyes, 24 eyes (38.1%) were diagnosed with neovascularization elsewhere (NVE) and/or neovascularization of the disc (NVD) and 39 eyes (61.9%) were diagnosed with tractional retinal detachment (TRD) preoperatively. The number of laser spots in the CPRP group ranged from 858 to 2245, with an average of 1232 (1048,1369) spots. The number of laser spots in the PPRP group ranged from 394 to 992, with an average of 673 (579, 798) spots. The mean logMAR BCVA before surgery was 1.71 ± 0.57 in the CPRP group and 1.57 ± 0.64 in the modified PPRP group, with no statistical difference between the two groups (P = 0.476). The mean logMAR BCVA was 1.15 ± 0.74 in the CPRP group and 0.77 ± 0.54 in the PPRP group at 3 months after surgery, showing that the PPRP group had more visual acuity improvement than the CPRP group (P = 0.037). There was a significant correlation between BCVA and the number of laser spots (P = 0.006). The difference of CMT between the two groups was statistically significant at 1 week after surgery (P = 0.02), but not at 3 months after surgery (P = 0.587). The postoperative inflammation in the CPRP group was significantly more severe than that in the PPRP group at the first day after surgery (P = 0.002). The postoperative inflammation in both groups was significantly reduced 3 months after surgery, with no statistical difference (P = 0.593). There was a significant correlation between the degree of inflammation and the number of laser spots at the first day after surgery (P = 0.016). There was no significant difference in the incidence of other complications between the two groups.

The modified PPRP technique was used during PPV in patients with PDR in this study, resulting in better BCVA, decreased CMT, and reduced early postoperative inflammation without increasing the incidence of adverse events in PDR.