vaned type looks like a thin sheet rising up from the base over an oval-shaped optic disc. There are 25-30 thin folds extending out from the sheet. The folds are roughly trapezoidal, short on the top and long on the base. See Figure 507 for an example.

The pleated type looks like an accordion. The base is longer than the top. There is usually a ridge at the top called the "bridge", which keeps the accordion shorter at the top. If the pectan is cut off from the retina at the base, then its bridge is cut off, then it can be flattened to