[Multiple patterns of angle closure mechanisms in primary angle closure glaucoma in Chinese]

Abstract

Objective: The mechanism of primary angle closure glaucoma (PACG) in Chinese is studied to establish a new classification system based on the etiology and mechanism of angle closure.

Methods: The anterior chamber angle's configuration and the anatomic structures related to the angle in 126 cases with PACG were observed with ultrasound biomicroscope (UBM), and the mechanisms of angle closure were analyzed by diagnostic treatment.

Results: Based on the configuration of the angle and anatomic structures related to the angle as well as the mechanisms of angle closure, PACG could be divided into following subtypes: pure pupillary block angle closure glaucoma [PPB, 48 cases (38.1%)]; pure non-pupillary angle closure glaucoma [PNP, 9 cases (7.1%)]; multiple mechanism angle closure glaucoma [MM, 69 cases (54.8%)]. PPB manifested that the relative position of pupillary margin was located anteriorly, the peripheral iris bombé was due to the pupillary block, and the angle closure was not related to the location and shape of the peripheral iris and ciliary body. PNP showed that the relative position of pupil margin was located posteriorly, the angle closure was not caused by the pupillary block, but caused by anterior located ciliary body and/or thick and anterior located peripheral iris. MM pattern was caused by both pupillary block and non-pupilary block, and most of the cases manifested creeping angle closure.

Conclusions: The angle closure mechanisms of PACG in Chinese are of multiple patterns. Based on the different mechanisms of angle closure in PACG, a new classification system should be established to improve the diagnosis and treatment of PACG.