Introduction: Plateau iris predisposes to the onset of an angle-closure glaucoma attack without pupillary block. This is a morphological anomaly of the iris characterized by anterior insertion, root thickness greater than the norm, and anterior rotation of the ciliary processes into the posterior chamber, pushing the base of the iris into the angle. Argon laser iridoplasty is useful to retract the peripheral iris using the thermal effect of the laser to widen the iridocorneal angle.
Materials and methods: The study investigated nine eyes of five patients who had had iridoplasty for iris plateau angle-closure glaucoma, diagnosed by dynamic gonioscopy (or indentation gonioscopy) and confirmed by ultrasound biomicroscopy (UBM). There were four females and one male, with a mean age of 42.2 years (range, 30-53 years). The mean intraocular pressure (IOP) before iridoplasty was 21.1 mmHg. The number of antiglaucoma treatments was 1 or 2, with all patients receiving miotic treatment. All patients had undergone argon laser iridotomy beforehand to remove the pupillary block frequently associated with iris plateau. Iridoplasty was done in two sessions with postoperative IOP-lowering treatment. The laser parameters used were: duration, 0.3 s; power, 500 mW; diameter, 300 microm.
Results: The postoperative IOP evaluated at 1 month was 14.4 mmHg with a reduction in the hypotensive treatment. No treatment was prescribed for four eyes, a single hypotensive treatment for four eyes, and two hypotensive medications for one eye.
Discussion: Pure iris plateau syndrome, leading to closure of the angle, is very rare compared to pupillary block, but these two mechanisms often co-exist. The physiopathology explains that the mechanism of isolated iris plateau is not modified by iridectomy. However, the advantage of argon laser iridoplasty, which retracts the periphery of the iris so as to widen the iridocorneal angle, must be emphasized. This technique can alleviate the need for high-risk filtering surgery, but longer follow-up is necessary to evaluate its duration and efficacy.