Plateau iris is defined as persistent iridotrabecular apposition after the placement of a peripheral iridotomy. On clinical examination, the anterior chamber may be deeper than is usual in angle-closure, and a characteristic “double hump sign” is seen on gonioscopy, with the proximal hump being due to the lens rise, and the distal hump being caused by the underlying and anteriorly located ciliary body. Plateau iris has the following characteristic findings on ultrasound biomicroscopy: an absent iridociliary sulcus, an anteriorly located ciliary body, and a centrally flat iris plane that is steep and narrow in the periphery where iridotrabecular contact is seen.¹
 
In general, plateau iris is found in 32% of primary angle-closure suspect eyes that undergo peripheral laser iridotomy.¹ Plateau iris tends to occur in younger people, it tends to cluster in families, and it tends to occur more frequently in atypical angle-closure suspects (e.g., pseudophakic and nearsighted eyes).^2-4 While a presumed diagnosis of plateau iris can be made clinically based upon persistent iridotrabecular trabecular apposition (not synechiae) after laser iridotomy, ultrasound biomicroscopy is ideally suited to confirm the diagnosis.
 
What is one to do when the angle remains closed after the placement of a laser iridotomy in the plateau iris? If the intraocular pressure is normal, the optic nerve is healthy, and the visual field is full, I would argue that nothing should be done, other than routine monitoring.
 
Laser iridoplasty is the placement of peripheral iris contraction burns (lower power, large spot size, longer duration) with the intention of opening up the drainage angle in plateau iris. While the intent of laser iridoplasty is to pull the angle open by contracting the peripheral iris, it has been suggested that the angle opening is simply created by thinning of the peripheral iris stroma with the contraction burns.⁵
 
We do not have prospective randomized trials demonstrating the efficacy of peripheral iridoplasty, although a recent case series did suggest that, in markedly elevated intraocular pressures with the plateau iris, iridoplasty can be associated with significant intraocular pressure reduction.⁶
 
Laser iridoplasty is generally well tolerated, but can be associated with prolonged inflammation and even pupillary abnormalities, including Urrets-Zavalia.⁷ It is controversial whether cataract extraction opens the angle in plateau iris. It has been reported that it does not; however, in one study, the presence of plateau iris was associated with better intraocular pressure reduction after cataract extraction in angle closure.^8,9
 
In summary, we have much to learn about plateau iris.