Pupillary Block, Aphakic Clinical Presentation

Symptoms of aphakic pupillary block may include the following:

• Painful red eye
• Blurry vision or acute decrease in vision
• Headache
• Nausea
• Vomiting

Slit lamp examination findings for aphakic pupillary block may include the following:

• Cornea: Epithelial and stromal edema may be seen.
• Anterior chamber

  • Overall shallowing of the anterior chamber with a normal or elevated IOP is the usual presenting sign of pupillary block. However, iris bombé is the classic presentation.
  • 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.
• Pupil

  • Seclusio pupillae or posterior synechiae may be seen.
  • A mushroomlike plug of vitreous protruding through the pupil may be seen.
• Gonioscopy

  • Forward bowing and convexity of the iris periphery is seen on gonioscopic evaluation.
  • Shallowing and then flattening of the anterior chamber results in the loss of view of the iridocorneal angle structures.
  • Initially, an appositional closure can be present, which may lead to permanent angle closure at a later stage.
  • PAS are evidence of chronicity.

A number of conditions predispose to the development of aphakic pupillary block, to include the following:

• Wound leakage can result in shallowing of the anterior chamber and can be associated with hypotony. This may be exaggerated by the rotation of the ciliary body and displacement of the vitreous, which can promote blockage of the pupillary aperture.
• Complete adhesion along the pupillary margin (seclusio pupillae) may result from any cause of severe postoperative inflammation (eg, retained lens material).
• Inadequate postoperative mydriasis
• Air bubble

  • Injection of air into the anterior chamber of a hypotonic eye following cataract extraction has been shown to be potentially hazardous.
  • Preoperatively, some eyes are rendered hypotonus by osmotic agents (eg, mannitol, glycerol), and these eyes may accept a considerable amount of air at the end of the surgery.
  • With resumption of normal fluid volume, the air will be compressed and forced into the posterior chamber, causing the iris to move forward leading to pupillary block. This condition is usually self-limited with resorption of the air bubble.
• Gas bubble

  • In an aphakic eye, a gas bubble anterior or posterior to the iris may interfere temporarily with the passage of aqueous humor across the pupil and predispose to pupillary block.
  • Pupillary block arises if the volume is of substantial amount as in the case of expanding gases (eg, sulfur hexafluoride [SF₆], octafluoropropane [C₃ F₈]) used in retinal reattachment surgery. Following expansion, these gases may occupy the entire vitreous cavity and displace the iris forward, subsequently blocking the pupil.
  • Kumar et al described a case of aphakic pupillary block following the use of perfluoropropane (or octafluoropropane) (C₃ F₈) at a nonexpansile concentration of 14%.^[1]
• Vitreous plugging

  • Vitreous gel has been recognized as an etiology of pupillary block by many authors. After intracapsular cataract extraction without sector iridectomy, the intact anterior hyaloid molds itself into the pupillary aperture leading to a secondary angle closure.
  • In some cases, even in the presence of small peripheral iridectomy, the vitreous can plug the openings and lead to angle closure. Shaffer observed that posterior vitreous detachment predisposed to such pupillary block.^[2]
  • Pupillary block by the vitreous has been described following surgical discission of posterior capsule as well as Nd:YAG laser posterior capsulotomy.
  • Posner has described 3 stages of pupillary block by the vitreous, as follows:^[3] (1) An early stage characterized by relative block due to decreased permeability of the hyaloid face. (2) A moderate stage with adhesions between the vitreous and sphincter pupillae referred to as sphincteric pupillary block. (3) The irido-hyloidal stage with extensive adhesions between the anterior hyaloid face and the entire posterior iris surface.
• Silicone oil

  • Pupillary block has been described in aphakic eyes after retinal reattachment surgery with silicone oil injection, both in the immediate and long-term postoperative periods.
  • Pars plana vitrectomy with silicone oil injection is being performed with increasing frequency in proliferative vitreoretinopathy. Because of the cohesive forces, the silicone oil takes a smooth spherical form within the aqueous in the vitrectomized posterior segment. Since silicone oil is lighter than aqueous humor, it settles superiorly behind the iris. Thus, a superiorly placed peripheral iridectomy may become blocked. In addition, if the silicone oil fills the vitreous cavity as the aqueous is being produced, it may force the silicone oil through the pupil. If the silicone oil completely fills the vitreous cavity, the pupillary space, and the entire anterior chamber, the IOP may rise further as aqueous humor may have no access to the trabecular meshwork.