Fig. 3. A. In a vitrectomized eye, the surfaces available for cellular proliferation posteriorly remain unchanged. Anteriorly, however, the residual vitreous base (and lens remnants if aphakic) can act as scaffolds for cells to proliferate on Cellular contraction results in the vitreous base being drawn anteriorly (black arrows) and circumferentially (thin black arrows). Note that with this anterior proliferation the retina posterior to the vitreous base is drawn into radial folds and the anterior retina is straightened. B. Because the retina is attached at the ora serrata, cellular contraction results in anterior displacement of the posterior vitreous base resulting in a peripheral trough whose depth and width is dependent on the anterior membrane attachments (e.g., ciliary body, posterior iris surface, pupillary margin).