Double Hump Sign in Indentation Gonioscopy is Correlated With Presence of Plateau Iris Configuration Regardless of Patent Iridotomy

Abstract

A double hump sign observed on indentation gonioscopy is strongly correlated with the presence of a plateau iris, and therefore a useful indicator of a plateau iris configuration regardless of the patency of a laser iridotomy. Thus, a plateau iris configuration can be detected without using a UBM in many cases.

Peripheral laser iridoplasty opens angle in plateau iris by thinning the cross-sectional tissues

“…Anterior segment imaging is a useful adjunct tool to gonioscopy for the evaluation of angles 2,5–8. SD-OCT is a noncontact imaging test that is relatively easy to perform.…”

“…It is commonly caused by anteriorly positioned ciliary processes that push the peripheral iris forward, resulting in angle closure. The diagnosis is always based on gonioscopic findings 1,2. Argon laser peripheral iridoplasty (ALPI) has been suggested to be useful in treating this condition by “stretching” the peripheral iris 3,4.…”

Plateau Iris and Ultrasound Biomicroscopy

“…In contrast, only 1 eye of 10 eyes without a double hump sign showed this UBM image. 3 We think that the gonioscopic appearance and UBM image generally agree regarding the iris configuration, as well as angle width. 4 Nevertheless, we agree that a study that fulfills the original diagnostic criteria should be conducted on normal patients to understand this iris configuration.…”

Laser Iridoplasty Techniques for Narrow Angles and Plateau Iris Syndrome

“…Dark room prone provocative testing involves having a patient sitting in a chair in a dark room with their head down for a duration of 1 h. An IOP elevation at the end of this time greater than 8 mmHg indicates a positive result. 39,40 The sensitivity and specificity of dark room testing, however, has not been validated in the literature; one consideration being the lability of IOP can be a function of POAG and unrelated to angle closure. 41 Pharmacologic testing utilizes a weak mydriatic such as cyclopentolate or phenylepineprhine.…”

“…Dynamic gonioscopy will also assess for the presence of the "double hump" sign created by the anterior ciliary body processes in plateau iris configuration. 39 A light touch is useful in performing routine gonioscopy; putting pressure on the lens to create indentation is very useful, but the examiner needs to be cognizant of how the lens is being held. Central anterior chamber depth will be relatively normal in plateau iris configuration.…”