Background: Previous studies report that the thickness of the peripheral retinal nerve fiber layer (RNFL) in individuals with Alzheimer's disease (AD) and mild cognitive impairment (MCI) is significantly thinner than in normal controls (NC), but RNFL thickness in different quadrants of the optic nerve remains unclear.
Aim: Conduct a systematic review of studies that assess peripheral RNFL thickness in AD and MCI.
Methods: Based on pre-defined criteria, studies in English or Chinese were identified from PubMed, Embase, ISI web of knowledge, Ovid/Medline, Science Direct, Cochrane Library, Chinese National Knowledge Infrastructure (CNKI), Chongqing VIP database, WANFANG DATA, and the China BioMedical Literature Service System (SinoMed). Review Manager 5.3 was used for analysis.
Results: The 19 cross-sectional studies identified had a pooled sample of 1455 individuals. There was substantial heterogeneity between studies that compared RNFL in AD or MCI to normal controls, but this heterogeneity was primarily restricted to low-quality studies. Combining 6 high-quality studies (n=578) indicated that total RNFL thickness and the thickness of superior and inferior RNFL quadrants in AD were significantly thinner than in normal controls. Similarly, combining 5 high-quality studies (n=541) indicated significantly thinner total RNFL thickness in MCI than in controls. Six studies (n=589) found thinner RNFL in the superior and inferior quadrants in MCI than in controls;and 6 studies (n=487) found thinner RNFL in the temporal quadrant in MCI than in controls. Finally, 7 studies (n=432) indicated that total RNFL was thinner in AD than in MCI, and 6 studies (n=364) indicated thinner RNFL in the superior and inferior quadrants in AD than in MCI.
Conclusion: Much of the heterogeneity in results from previous studies may be due to poor methodology. Peripheral RNFL thicknesses, particularly in the superior and inferior quadrants, becomes progressively thinner as cognitive function declines, so this could be a candidate biomarker for early identification of AD. Methodologically rigorous studies in large population-based cohort studies that follow elderly individuals over time and that simultaneously collect information on potential mediating factors (such as blood pressure, blood glucose, and lipid levels) are needed to confirm or disprove the potential predictive value of RNFL.
背景: 既往研究发现阿尔茨海默病(Alzheimer's disease, AD)和轻度认知障碍(mild cognitive impairment, MCI)患者外周视神经纤维层(retinal nerve fiber layer, RNFL)厚度显著薄于正常对照组(normal control, NC), 但视神经RNFL在各个象限的具体厚度尚不清楚。.
目的: 运用系统综述综合评估AD和MCI患者的外周RNFL厚度。.
方法: 按照预先制定的纳入和排除标准, 从PubMed、EMBASE、ISI Web of Knowledge、Ovid/Medline、Science Direct、Cochrane Library、中国知识资源总库(CNKI)、重庆维普数据库、万方数据和中国生物医学文献服务系统(SinoMed)筛选中英文研究。采用Review Manager 5.3软件进行统计分析。.
结果: 共纳入19项横断面研究(含合并样本量1455例)。通过比较AD或MCI患者和正常对照的RNFL, 发现各研究间的异质性很大, 但这种异质性主要限于低质量研究。合并其中6项高质量研究(n=578)后发现AD患者总的RNFL和上、下方象限的RNFL厚度较正常对照明显变薄。类似地, 合并5项高质量研究(n=541)后发现MCI患者总的RNFL厚度显著薄于对照组。有6项研究(n=589)发现MCI患者的上、下象限RNFL比对照组薄;而另外6项研究(n=487)发现MCI患者颞象限RNFL比对照组薄。最后, 有7项研究(n=432)表明AD患者的总RNFL比MCI患者薄, 而有6项研究(n=364)显示AD患者的上、下象限RNFL比MCI患者薄。.
结论: 既往研究结果的大部分异质性可能是由于方法学的不足。外周RNFL的厚度, 特别是在上、下象限, 在认知功能下降的同时逐渐变薄, 所以这可以作为AD早期识别的候选辅助生物标记。我们需要进一步开展在方法学上更有说服力的、基于人群的队列研究来随访老年患者并同时收集潜在中介因素的信息(如血压、血糖和血脂水平), 从而证实或证伪RNFL潜在的预测价值。.
中文全文: 本文全文中文版从2016年2月26日起在http://dx.doi.org/10.11919/j.issn.1002-0829.215100可供免费阅览下载.
Keywords: Alzheimer’s disease; meta-analysis; mild cognitive impairment; retinal nerve fiber layer.