a ‘‘Kruckenberg spindle’’ (Fig. 6). The posterior surface of the iris rubs against the anterior lens zonules and releases pigment into the anterior chamber and trabecular meshwork. At the slit lamp, the examiner frequently can see a posteriorly directed concavity of the peripheral iris. Posterior bowing of the iris has been related to reverse pupillary block secondary to accommodation.10,11 The UBM can confirm this iris configuration.12

Synechiae

Peripheral anterior synechiae, or adhesions of the peripheral iris to the trabecular meshwork and other angle structures, may be visible at the slit lamp if the synechiae are high enough. Gonioscopy can establish the extent of synechial angle closure. The UBM shows a tenting of the peripheral iris to the peripheral cornea and trabecular meshwork (Fig. 7).

Iridocorneal Endothelial Syndromes

In the rare iridocorneal endothelial syndromes, abnormal epithelium grows over the iris surface

creating a range of clinical pictures. Chandler’s syndrome has a predominance of corneal endothelial findings. In Cogan Reese syndrome, marked iris changes occur with correctopia, iris tears, and polycoria. Iris nevus syndrome has the clinical appearance of multiple iris nevi on the surface of the iris. These are not true iris nevi but are isolated elevations of anterior iris stroma surrounded by abnormal epithelium. UBM scanning of the eye shows iris defects and surface abnormalities and the high peripheral anterior synechiae typically seen in this syndrome (Fig. 8). Glaucoma is a frequent sequel of the iridocorneal endothelial syndromes because of the angle closure caused by formation of extensive and high peripheral anterior synechiae.

Scleritis

Scleritis is an uncommon cause of angle-closure glaucoma. Anterior scleral edema pushes the ciliary body internally and anteriorly; the peripheral iris then can rotate into the angle, causing angle closure. UBM shows the absence of space between the peripheral cornea and iris and between the

peripheral posterior iris surface and the ciliary processes of the ciliary body. This form of angle closure usually does not respond to laser peripheral iridotomy. Topical cycloplegia with an

anticholinergic agent such as atropine 1% is the preferred management, but a laser peripheral iridoplasty may become necessary in some cases (see the article by Lowder, elsewhere in this issue).