Primary angle closure glaucoma in Chinese and Western populations

目的：原发性闭角型青光眼的研究进展。方法：对近年来中国眼科学以及国外学在这方面的这方面的研究工作特别是对超声生物显微镜用于原发性闭角型青光眼研究后的研究工作及有关献进行了归纳和复习。结果：根据房角关闭，中国人的原发性闭角型青光眼可分为三种类型：1.多种机制共存型。2.单纯瞳孔阻滞型。3.非瞳孔阻滞型。由于多种机制共存型闭青的临床特点及对治疗的反应不同于其它类型闭青，除了要解除其瞳孔阻滞因素外，同时要针对性地处理共同存在的非瞳孔阻滞因素。结论：超声生物显微镜在闭青的研究、诊断以及对治疗效果的评价方面的应用促进了闭青的认识，随着这一技术的普及，将大大提高闭青的诊治水平。

Primary angle closure glaucoma in Chinese and Western populations

Objective To review the major progress in primary angle closure glaucoma (PACG).Methods Contents of this article were selected from the original papers or reviews related to primary angle closure glaucoma published in Chinese and foreign journals. A total of 76 articles were selected from several hundred original articles or reviews. The content of selected articles is in accordance with our purpose and the authors are authorized scientists in the study of glaucoma.Results Primary angle closure glaucoma is the most common type of glaucoma in the Sino Mongoloid population. PACG in Chinese can be classified into three types depending on the mechanism of angle closure: 1. Multimechanism: 54.8% of Chinese PACG is caused by co existing factors. The pattern of angle closure appears to mainly be creeping closure. After iridectomy, almost 40% of the cases still manifest a positive response to the darkroom provocative test and progressive synechial closure or recurrent angle closure may occur. Several mechanisms are involved in this form of PACG such as pupillary blocking component, iris crowding component and anterior positioned ciliary body. These factors can coexist in the follow patterns: pupillary blocking and iris crowding coexist; pupillary blocking and anterior positioned ciliary body coexist or three of them co exist. 2. Pupillary block: (38.1% of Chinese PACG) is caused by iris bombe due to pupillary block with acute or subacute attack. It responds well to iridectomy or laser iridotomy. 3. Non pupillary blocking: (7.8% of Chinese PACG). They usually have a deeper anterior chamber, and tend to be younger (below 40 years of age). Angle closure in this form of PACG is caused by: iris crowding mechanism or/and anteriorly positioned ciliary body against iris root to angle. It is critical to distinguish multi mechanism PACG from other types. The initial treatment for this type of PACG is also iridectomy, but after the pupillary block component is eliminated by iridectomy, the residual non pupillary blocking components should be highlighted by a diagnostic treatment procedure or by a ultrasound biomicroscopy (UBM) provocative test. Finally, the role of UBM in the observation and evaluation of the mechanism of angle closure is discussed and future research directions on PACG in Asians are proposed. Conclusion Chinese eyes have been recognized to be prone to the development of creeping angle closure. There is some direct evidence that creeping angle closure is caused by multiple mechanisms. Further study on this topic is needed.