Predictibility of the efficacy of peripheral iridotomy in primary angle closure: Utility of UBM

To assess the utility of UBM in the management of primary angle closure (PAC) and assessing the predictability of peripheral iridotomy (PI) in re-opening the closed angle.

Retrospective clinical study.

Patients with suspicion of PAC.

This study obtained the consent of all patients and adhered to the Declaration of Helsinki. It was conducted in two ocular imaging centers and based on patients with suspected PAC. Each patient underwent UBM and Visante OCT at each visit, before and after PI when PAC was confirmed.

Irido-corneal angle.

Out of 202 eyes (101 patients) with a mean age of 62 years and 69.3% female predominance, we found 186 eyes with PAC. In most cases (77.4%), the iridocorneal angle was open after a single PI at the second visit, and only 14% eyes remained closed at the third visit, regardless of any additional treatment performed (complementary PI, iridoplasty, surgical lens extraction). Mechanisms involved in persistent angle closure after PI were: imperforate PI (45.2% of eyes), iris plateau syndrome (8.6% of eyes), significant lens vaulting (30.9% of eyes) and mixed mechanisms (2.3% of eyes).

PI remains effective as a first-line treatment in most cases of PAC, even when associated with mechanisms other than pupillary block. Nevertheless, the PI must be completely patent, and UBM can help in understanding underlying mechanisms, hence guiding the treatment in these eyes.