[Focusing on the functional dry eye].

Dry eye is one of the most common eye diseases characterized by disturbance of tear film homeostasis and a series of ocular discomforts. Discrepancy of ocular subjective symptoms and objective signs, especially unexplained severe symptoms without visible signs has been a long-time confusion for ophthalmologists. Functional disorder is a medical condition that impairs normal functioning of bodily processes due to autonomic nervous dysfunction caused by cerebral cortical dysfunction, but at the exterior, there is no appearance of abnormality. Clinical manifestations are the disease symptoms with a lack of exact physical signs and examination results to confirm the diagnosis. According to the definition and characteristics of functional disorder, we put forward the concept of functional dry eye. We assume that those patients with dry eye symptoms but without detectable signs could be classified into such a functional dry eye subtype. The possible mechanism, clinical manifestations, and treatment strategies are further discussed. (Chin J Ophthalmol, 2019, 55: 885-890).干眼是最常见的眼科疾病，以泪膜稳态失衡为主要特征，并伴有眼部不适症状。但在临床工作中，部分干眼患者眼部有明显症状而无体征，给干眼的临床诊治带来困扰。功能性疾病是指由于大脑皮层功能失调导致自主神经功能紊乱而产生一系列临床症状，但组织结构未发生改变的一类非器质性疾病，临床表现为具有疾病的症状但缺乏确切体征及异常检查结果以明确诊断。根据功能性疾病的特点，本文提出"功能性干眼"的概念，并对其可能的机制、临床表现、处理以及目前存在的问题进行阐述，以期眼科医师共同关注并进行深入研究和探讨。（中华眼科杂志，2019，55：885-890）.