To evaluate the efficacy of the pattern scan laser (PASCAL) in treating newly diagnosed high-risk proliferative diabetic retinopathy (PDR).

Retrospective comparative case series.

setting: Institutional. study population: Eighty-two consecutive eyes of the same number of patients with newly diagnosed high-risk PDR treated with panretinal photocoagulation (PRP) using either argon green laser (41 eyes treated before February 2007) or PASCAL (41 eyes treated February 2007 or thereafter), then followed for at least 6 months. procedure: Retrospective chart review with attention to main outcome measures, age, sex, race, follow-up interval, insulin dependence, hemoglobin A1c, and total number of lasers spots. main outcome measures: Persistence or recurrence of neovascularization, incidence of vitreous hemorrhage (VH), neovascularization of the iris (NVI), neovascular glaucoma (NVG), and need for vitrectomy.

Patients treated with the PASCAL and argon laser received a similar number of spots (1438 vs 1386; P = .59). Patients treated with the PASCAL were more likely to experience persistence or recurrence of neovascularization within 6 months of initial treatment (73% vs 34%; P < .0008). The study was not adequately powered to detect a significant difference in incidence of vitreous hemorrhage, NVI, NVG, or need for vitrectomy.

When using traditional laser settings, PRP performed with the PASCAL is less effective than that performed with traditional argon laser in effecting lasting regression of retinal neovascularization in the setting of previously untreated high-risk PDR. Physicians may need to change treatment parameters when using PASCAL pattern laser therapy for high-risk PDR.