Hypotony due to loose suturing of the corneoscleral wound or hyperfiltration of a trabeculectomy may lead to a vicious cycle of anterior chamber shallowing, forward displacement of the iris-capsule diaphragm, and aqueous misdirection and further anterior chamber shallowing. The absence of a functioning iridectomy predisposing to relative pupillary block may be one of the initial phases in the spectrum of aqueous misdirection. The distinguishing feature is a subnormal IOP in the case of choroidal separation, while this is normal or elevated in pupillary block. Gonioscopy and tonometry evaluation of optic nerve head and visual fields may be performed. The management of pupillary block involves early recognition, relief of the pupillary block, medical treatment, and surgical treatment.
Medical treatment consists of intensive cycloplegia, mydriasis, and aqueous suppressants.
In very early cases, it may be possible to relieve the block by the vigorous use of strong mydriatics alone or with hyperosmotic agents. Posterior synechiae may be broken and herniation of a mushroomlike plug of vitreous may be relieved. Miotic agents are rarely successful and should be used with caution in patients with an abnormal retina. The length of time that the angle had remained closed is crucial in deciding the appropriate treatment. Usually, a peripheral iridotomy or incision of the hyaloid membrane is adequate to relieve the block.