Singh Ajay K, Verma Shilpa
Consultant and Anterior Segment Surgeon, Department of Ophthalmology, Asian Institute of Medical Sciences, Faridabad, Haryana, India.
WNS Global Services Pvt. Ltd., Gurugram, Haryana, India.
Indian J Ophthalmol. 2020 Apr;68(4):555-561. doi: 10.4103/ijo.IJO_999_19.
Alzheimer's disease (AD) is the most common neurodegenerative disease worldwide which unfortunately has no known effective cure to date. Despite many clinical trials indicating the effectiveness of preclinical treatment, a sensitive tool for screening of AD is yet to be developed. Due to multiple similarities between ocular and the brain tissue, the eye is being explored by researchers for this purpose, with utmost attention focused on the retinal tissue. Besides visual functional impairment, neuronal degeneration and apoptosis, retinal nerve fiber degeneration, increase in the cup-to-disc ratio, and retinal vascular thinning and tortuosity are the changes observed in the retinal tissue which are related to AD. Studies have shown that targeting these changes in the retina is an effective way of reducing the degeneration of retinal neuronal tissue. Similar mechanisms of neurodegeneration have been demonstrated in the brain and the eyes of AD patients. Multiple studies are underway to investigate the potential of diagnosing AD and detection of amyloid-β (Aβ) levels in the retinal tissue. Since the tissues in the anterior segment of the eye are more accessible for in vivo imaging and examination, they have more potential as screening biomarkers. This article provides a concise review of available literature on the ocular biomarkers in anterior and posterior segments of the eye including the cornea, aqueous humour (AH), crystalline lens, and retina in AD. This review will also highlight the newer technological tools available for the detection of potential biomarkers in the eye for early diagnosis of AD.
阿尔茨海默病（AD）是全球最常见的神经退行性疾病，遗憾的是，迄今为止尚无已知的有效治愈方法。尽管许多临床试验表明临床前治疗有效，但尚未开发出一种用于筛查AD的敏感工具。由于眼组织与脑组织之间存在多种相似性，研究人员正为此探索眼睛，其中视网膜组织受到了极大关注。除了视觉功能障碍、神经元变性和凋亡外，视网膜神经纤维变性、杯盘比增加以及视网膜血管变细和迂曲是在视网膜组织中观察到的与AD相关的变化。研究表明，针对视网膜中的这些变化是减少视网膜神经元组织变性的有效方法。在AD患者的大脑和眼睛中已证明存在类似的神经变性机制。多项研究正在进行中，以调查在视网膜组织中诊断AD和检测淀粉样β蛋白（Aβ）水平的潜力。由于眼前节组织更便于进行体内成像和检查，它们作为筛查生物标志物具有更大的潜力。本文简要综述了有关AD患者眼前后节包括角膜、房水（AH）、晶状体和视网膜中眼部生物标志物的现有文献。本综述还将重点介绍可用于检测眼中潜在生物标志物以早期诊断AD的更新技术工具。
