In general, membranes identified as PVR had many more Ki-67-positive cells in comparison to those in the other three categories, with the average number of Ki-67-positive cells identified per mm2 of tissue being 20.9 for proliferative diabetic retinopathy, 138.3 for PVR, 12.2 for post–retinal detachment, and 19.3 for idiopathic ERM. This evidence concerns the gene MKI67 and proliferative diabetic retinopathy.