Plateau Iris Glaucoma Clinical Presentation

Updated: May 06, 2016
  • Author: Jim C Wang (王崇安), MD; Chief Editor: Hampton Roy, Sr, MD  more...
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Presentation

History

Patients with plateau iris tend to be female, in their 30-50s, hyperopic, and often have a family history of angle-closure glaucoma.

Patients may present with angle closure, either spontaneously or after pupillary dilation.

More commonly, the diagnosis of plateau iris configuration is made on routine examination.

Plateau iris syndrome usually is recognized in the postoperative period when the angle remains persistently narrow in an eye after iridotomy.

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Physical

Slit lamp examination of patients with plateau iris usually shows normal anterior chamber depth with a flat or slightly convex iris surface.

On gonioscopy, the angle is extremely narrowed or closed, with a sharp drop-off of the peripheral iris. When indentation gonioscopy is performed, the double-hump sign is seen. The more peripheral hump is determined by the ciliary body propping up the iris root, and the more central hump represents the central third of the iris resting over the anterior lens surface. The space between the humps represents the space between the ciliary processes and the endpoint of contact of the iris to the anterior lens capsule. More force often is needed to open the angle on indentation gonioscopy than on pupillary block angle closure.

Plateau iris syndrome is characterized by persistent angle occludability (spontaneous, in the dark, or after dilation) in an eye with a patent iridotomy. The level of the iris stroma in relation to the angle structures, referred to as the height of the plateau, differentiates the 2 subtypes of plateau iris syndrome.

In the complete syndrome, the angle is occluded to the upper trabecular meshwork or the Schwalbe line and intraocular pressure (IOP) rises.

Incomplete plateau occludes the angle to mid level, leaving the upper portion of the filtering meshwork open and IOP unchanged. This latter situation is far more common and is clinically important because these patients can develop peripheral anterior synechiae (PAS) and synechial angle closure years after a successful iridotomy. Therefore, patients with open angle after iridotomy should not be assumed to be cured. The angle can narrow further with age, and angle closure can occur years later.

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Causes

Plateau iris results from large or anteriorly positioned ciliary processes holding forward the peripheral iris and maintaining its apposition to the trabecular meshwork. The etiology underlying this anterior displacement of the pars plicata is unclear but probably represents an anatomic variant.

No indication exists of any abnormality of the ciliary body that would cause such forward rotation of the ciliary processes. The possibility that the lens-zonule apparatus is pulling the process forward is unlikely because of the observation that in pseudophakic patients the iris processes remain in a forward position, despite the posterior position of the posterior chamber lens.

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