Aphakia means absence of the crystalline lens. It may occur as a result of trauma, lens subluxation, or dislocation and surgical management of visually significant cataract. Aphakia was especially common during the intracapsular cataract extraction era. Pupillary block is a complication of cataract surgery with or without lens implantation. This is also possible with round-pupil cataract extraction if an iridectomy was performed but was small and placed in the extreme periphery.
Pupillary block is the most common mechanism of angle closure after cataract extraction.
This mechanism can be divided into 2 types namely, anterior and posterior pupillary block. A firm apposition between the pupillary margin and other surfaces anterior or posterior to the iris may lead to a pupillary block. The pupillary aperture may be obstructed by the anterior hyaloid surface, the intraocular lens, or the posterior capsule. A postoperative inflammation following an intracapsular cataract extraction may cause complete posterior synechiae between the iris and the intact anterior hyaloid membrane. A shallow anterior chamber favors formation of these adhesions.