Fig. 29. Anterior proliferative vitreoretinopathy. Top left. Anteroposterior traction with the posterior border of the vitreous base displaced toward its anterior insertion, creating a trough or concavity. Top right. Anteroposterior traction with the posterior border to the vitreous base adherent to the pars plicata. Bottom left. Anteroposterior traction with the posterior border of the vitreous adherent to the posterior iris surface. Note the posterior retraction of the iris. Bottom right. Anteroposterior traction with the posterior border of the vitreous base adherent to the pupillary margin. Note the marked posterior retraction of the iris. (Lewis H, Aaberg TM: Anterior proliferative vitreoretinopathy. Am J Ophthalmol 1988;105:277)