Kim Kyeong Hwan, Mian Shahzad I
aDepartment of Ophthalmology, Inje University College of Medicine; and Haeundae Paik Hospital, Busan, South Korea bDepartment of Ophthalmology and Vision Science, W. K. Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, USA.
Curr Opin Ophthalmol. 2017 Jul;28(4):355-362. doi: 10.1097/ICU.0000000000000387.
A state of limbal stem cell deficiency (LSCD) can be secondary to a number of etiologies, resulting in either a reduction in the total number of limbal stem cells or an abnormality in stem cell function. Initially, the epithelium becomes irregular and hazy; however, this condition may progress to persistent corneal epithelial defects, stromal scarring, ulceration, and even perforation. Since LSCD secondary to a variety of etiologies may be reversible, and various factors are prognostic of disease progression, timely diagnosis is important. This review will describe current knowledge of diagnostic techniques for LSCD and understanding of epithelial stem cell function.
Conjunctivalization, regarded as the most reliable clinical finding diagnostically, can be identified as late staining of epithelium with fluorescein. While identifying loss of the palisades of Vogt by slit-lamp examination, can provide a high suspicion of LSCD, but this is not diagnostic. Impression cytology is a simple, noninvasive technique that aids in the diagnosis of LSCD, but a negative result also cannot rule out the diagnosis. Recent findings have also shown that imaging techniques including in-vivo confocal microscope and optical coherent tomography can also aid in diagnosing LSCD; however, several challenges remain before these techniques become standard diagnostic methods in clinical practice. Meanwhile, determination of the absence of limbal epithelial crypts and focal stromal projections using image reconstruction techniques may assist in the diagnosis of LSCD. Furthermore, histologic markers may help not only to improve sensitivity and specificity of conventional techniques in diagnosis of LSCD, but also to identify human limbal stem cells and determine their number and function in LSCD.
Efforts to develop and improve techniques for diagnosing LSCD are ongoing. Increased knowledge of limbal stem cells and components of their niches may not only help in understanding the pathogenesis of LSCD but may improve its diagnosis, thereby ameliorating the prognosis of patients with this devastating disease.
角膜缘干细胞缺乏（LSCD）状态可能继发于多种病因，导致角膜缘干细胞总数减少或干细胞功能异常。起初，上皮会变得不规则且模糊；然而，这种情况可能进展为持续性角膜上皮缺损、基质瘢痕形成、溃疡，甚至穿孔。由于继发于多种病因的LSCD可能是可逆的，且多种因素可预测疾病进展，因此及时诊断很重要。本综述将描述目前关于LSCD诊断技术的知识以及对上皮干细胞功能的理解。
结膜化被认为是诊断中最可靠的临床发现，可表现为上皮细胞对荧光素的晚期染色。通过裂隙灯检查发现Vogt栅栏消失，虽可高度怀疑LSCD，但不能确诊。印迹细胞学检查是一种简单的非侵入性技术，有助于LSCD的诊断，但阴性结果也不能排除诊断。最新研究结果还表明，包括活体共聚焦显微镜和光学相干断层扫描在内的成像技术也有助于诊断LSCD；然而，在这些技术成为临床实践中的标准诊断方法之前，仍存在一些挑战。同时，利用图像重建技术确定角膜缘上皮隐窝缺失和局灶性基质突起可能有助于LSCD的诊断。此外，组织学标志物不仅有助于提高传统技术在LSCD诊断中的敏感性和特异性，还可用于识别人类角膜缘干细胞并确定其在LSCD中的数量和功能。
目前正在努力开发和改进LSCD的诊断技术。对角膜缘干细胞及其微环境成分的深入了解不仅有助于理解LSCD的发病机制，还可能改善其诊断，从而改善这种毁灭性疾病患者的预后。
