Objective: In previous decades, glaucoma has been primarily attributed to elevated intraocular pressure (IOP), but this has gradually been replaced by the development of optic neuropathy as the central concept of glaucoma in developed countries. However, there still remain strong controversies in the definition of glaucoma in China. In this current review, we are going to discuss these controversies and elaborate on the historical transitions of the definition of glaucoma both in China and developed countries. Furthermore, we will briefly describe the "ocular-cranial pressure gradient" theory and discuss the relationship between glaucoma and degenerative diseases of the central nervous system (CNS) in order to show the complex pathogenesis of glaucoma and the importance for the modification to the definition of glaucoma.
Data sources: We performed a comprehensive search in both PubMed and SinoMed using the following keywords: (a) "primary glaucoma" and "guideline," (b) "ocular-cranial pressure gradient," and (c) "glaucoma," "Alzheimer's disease," and "Parkinson's disease." The literature search included the related articles with no restrictions on publication date.
Study selection: The primary references were Chinese and English articles including (a) original guidelines and expert consensuses of primary glaucoma, (b) reviews focusing on the differences between various versions of these guidelines and consensuses, and (c) papers about ocular-cranial pressure gradient theory and the relationship between glaucoma and CNS degenerative diseases.
Results: The definitions and classifications of both primary open-angle glaucoma and primary angle-closure glaucoma differ between Chinese glaucoma consensuses and international primary glaucoma guidelines. Chinese definitions and classifications put more emphasis on the IOP, while international guidelines put more emphasis on the presence of optic neuropathy. The ocular-cranial pressure gradient theory and the research on the relationship between glaucoma and CNS degenerative diseases have provided new directions for exploring the pathogenesis of glaucoma.
Conclusions: As regards the definition and classification of primary glaucoma, we find that there are still some discrepancies between Chinese expert consensuses and international guidelines. Glaucoma is a disease with complex etiologies, while its common characteristic is a specific optic neuropathy. The current definition and understanding of glaucoma is an ongoing and evolving process, reflecting our latest available evidence on its pathogenesis. Chinese ophthalmology community may need to update our guidelines, accommodating these latest developments.
原发性青光眼内涵演变与定义变迁 摘要 目的：近年来，“特征性的视神经损害”逐渐取代了“病理性高眼压”成为发达国家青光眼临床定义的核心内涵。然而，上述青光眼内涵演变与定义变迁在我国尚存在广泛争议。本文阐述了国内外原发性青光眼内涵演变与定义变迁的历史，尝试剖析其主要脉络，并且探讨了当前存在的主要争论以及亟待解决的问题。同时本文简述了眼颅压力梯度理论和青光眼与中枢神经系统变性疾病之间关系的新进展，以体现青光眼病因的复杂性以及更新对青光眼的定义和理解的重要性。 数据来源：在PubMed和SinoMed分别检索：（1）“原发性青光眼”和“指南”；（2）“眼颅压力梯度”；（3）“青光眼”，“Alzheimer's 病”和“Parkinson's 病”。检索年限不限。 研究选择：语言为中文和英文，文献为各版原发性青光眼指南和专家共识以及重点阐述各版本指南和专家共识之间差异的综述性文章，还有关于眼颅压力梯度理论及青光眼与中枢神经系统变性疾病之间关系的论文。 结果：国内原发性青光眼专家共识与国际上原发性青光眼指南在POAG和PACG的定义及分类上存在差异。在国内的定义和分类中，强调眼压的重要作用；国际指南中的定义和分类则强调青光眼的本质是一种视神经疾病。眼颅压力梯度理论的提出和青光眼与中枢神经系统变性疾病之间关系研究的新进展，为理解青光眼的病因提供了新的思路和研究方向。 结论：对于原发性青光眼的定义和分类，国内专家共识与国际指南之间尚存一定的差异。青光眼是一种由多种复杂病因造成的、以特异性视神经损害为特征的疾病。随着对青光眼病因研究的不断深入，我们对青光眼的理解和定义也将不断发展和更新。.
Keywords: Central Nervous System Degenerative Disease; Intraocular Pressure; Ocular-Cranial Pressure Gradient; Optic Neuropathy; Primary Glaucoma.