Plateau Iris

In a minority of eyes that develop primary angle-closure glaucoma, the anterior chamber does not appear as shallow as we are accustomed to associate with angle-closure glaucoma, and the front surface of the iris lacks the overall convex curvature that usually involves the whole iris from pupil to angle. In angle-closure glaucoma associated with the so-called plateau iris or flat iris plane, the surface of the iris extending from the pupil toward the angle may appear nearly flat centrally; it may be convex only in the far periphery, where it conforms to the curvature of the angle wall and closes the angle. The profile of such an iris, if it could be seen in cross-section, can be conceived as resembling a plateau, as pointed out by Tornquist in 1958. ¹.