Curran, barkan, and chandler: a history of pupillary obstruction and narrow angle glaucoma.

Edward J. Curran was the first to show that glaucoma could be caused by an impedance to the flow of aqueous through the pupil and that iridectomy removed the obstruction. He observed that full iridectomy was not necessary because the iris lay so heavily on the lens that forward flow could only occur at the periphery; so only a small peripheral hole was required. By gonioscopy, Barkan divided glaucoma into two types according to the site of mechanical block: (a) within the trabecular spaces (wide-angle) or (b) narrow angle blocked by iris against the trabecular spaces (narrow-angle or iris block glaucoma). Progress was slow, and not until 1951 in articles by Haas and Scheie, and by Chandler, were the full mechanisms of pupillary obstruction (narrow angle closure) peripheral iridectomy explained. Only later, with laser iridotomy, were all of Curran's goals achieved when no instruments had to enter the anterior chamber to relieve the pupil block and either prevent angle closure or allow angles to reopen.