This is the posterior pupillary block. The block impedes the forward movement of the aqueous to the anterior chamber leading to iris bomb , obstruction of the angle, and possible formation of peripheral anterior synechiae. A similar mechanism of pupillary block is seen with phacomorphic glaucoma and is referred to as anterior aqueous misdirection perilenticular. The aqueous humor accumulates around and behind the crystalline lens leading to lens-iris contact and the obstruction of anterior aqueous movement. The absence of an iridectomy facilitates the development of a pupillary block.
Many cases are asymptomatic and are only recognized during routine examination.
The time of presentation is variable. Pupillary block may present in the immediate postoperative period but has been described even weeks to years after surgery. Anterior chamber Overall shallowing of the anterior chamber with a normal or elevated IOP is the usual presenting sign of pupillary block. The disparity between the central and the peripheral anterior chamber depth, with a deeper central depth is a result of posterior synechiae. The presence of inflammatory debris or blood may cause an unevenness in the anterior chamber depth.