ULTRASOUND BIOMICROSCOPIC FEATURES OF PIGMENTARY GLAUCOMA

We have developed a device capable of producing subsurface images in e yes at microscopic resolution. We call this method ''ultrasound biomic roscopy.'' We examined 19 patients with pigmentary glaucoma or pigment ary dispersion syndrome using ultrasound biomicroscopy. Ten patients w ere found to have concave irides with small distances between the back of the iris and the zonule. In these patients iris-lens contact was g reater than in patients without iris concavity and healthy patients. N ine patients did not show iris concavity or increased iris-lens contac t. The finding of iris concavity and increased iris-lens contact is co mpatible with a theory of reverse pupil block producing intermittent i ris-zonule touch, with a valve effect preventing posterior flow of aqu eous. This theory was supported by the loss of concavity following iri dotomy in three patients. The force that produces a reversal of the no rmal pressure gradient remains unclear, but recent evidence suggests t hat accommodation plays a major role. The patients who did not show ir is concavity and increased iris-lens contact may have been examined at a time when these forces were not acting or had ceased to act.