Severe proliferative diabetic retinopathy treated with vitrectomy or panretinal photocoagulation: a monocenter randomized controlled clinical trial

Objective: Visual and anatomic results of pars plana vitrectomy were compared with panretinal photocoagulation in cases of severe proliferative diabetic retinopathy. Design: Monocenter randomized controlled clinical trial; randomization and allocation to trial group were carried out by a central computer system. Participants: We studied 180 eyes of 180 patients with severe proliferative diabetic retinopathy, half with tractional retinal detachment not involving the macula (n = 90). Some were treated by pars plana vitrectomy (n = 90) and some by panretinal photocoagulation (n = 90). Methods: Eyes were randomly divided into 2 groups. Group 1 was treated with pars plana vitrectomy, membrane and internal limited membrane peeling, panretinal photocoagulation, and focal or grid macular laser. Group 2 was treated with panretinal photocoagulation and focal or grid macular laser. Follow-up was at least 12 months. Results: Mean preoperative visual acuities and ophthalmic fundus characteristics were compared across groups. A year postoperation, visual acuity (the primary endpoint) in group 1 improved in 30 eyes (33%); was unchanged in 22 eyes (25%); and decreased in 38 eyes (42%). In group 2, visual acuity improved in 32 eyes (35%); was unchanged in 42 eyes (47%); and decreased in 16 eyes (18%). The percentage of improvement in the 2 groups was not statistically significant (p = 0.75), whereas the stabilized (p = 0.002) and worsened eyes (p = 0.0003) in group 1 and group 2 were significantly different. Conclusion: In cases of severe proliferative diabetic retinopathy, even with tractional retinal detachment not involving macula, it is best to defer vitrectomy unless definite progression that threatens the vascular center is documented.