Patency of small laser iridotomy evaluated using anterior-segment optical coherence tomography
A 49-year-old Japanese man presented with blurred vision in both eyes. Intraocular pressure (IOP) was 42 mmHg in the right eye and 70 mmHg in the left eye. Slit-lamp examination showed a cloudy cornea, and gonioscopy showed anterior chamber angle closure in both eyes. The patient was diagnosed with bilateral acute angle-closure glaucoma, and neodymium-doped yttrium aluminum garnet (Nd:YAG) laser iridotomy was performed to eliminate pupillary block in both eyes. After the procedure, IOP decreased to a normal level.\nOne month later, however, the patient presented with blurred vision in the right eye. Best-corrected visual acuity was 20/16 bilaterally. IOP was 70 mmHg in the right eye and 23 mmHg in the left eye. Slit-lamp examination of the right eye showed a cloudy cornea. Despite its small size, the previous laser iridotomy was observed at the 10 o’clock position in the iris (). Transillumination through the opening was also observed. Gonioscopy showed angle closure in all four quadrants. Following compression, gonioscopy showed that the closure was partially appositional, and more than half of the angle had synechiae. Based on the sudden IOP elevation associated with a cloudy cornea and blurred vision, we suspected recurrent acute angle-closure glaucoma in this patient, although the initial iridotomy appeared open on slit-lamp examination.\nTo further evaluate the precise condition of the initial laser iridotomy, we referred to cross-sectional images obtained using AS-OCT (CASIA SS-1000; Tomey Corporation, Nagoya, Japan). The angle mode was used for evaluation. The images showed a membrane that was not observed by slit-lamp examination, with an anterior bowing configuration at the base of the iridotomy (), suggesting increased fluid pressure in the posterior chamber. This observation indicated that pupillary block was the causative mechanism of the increased IOP in our patient, and retreatment with Nd:YAG laser iridotomy was performed at the same site.\nAfter the procedure, the IOP decreased to 9 mmHg. The anterior lens capsule was observed through the opening by slit-lamp examination (). A cross-sectional image showed a completely penetrated iridotomy with widening of the anterior chamber angle and straightening of the iris ().