School of Optometry and Vision Science, University of New South Wales, Sydney, Australia.
Stats Central, Mark Wainwright Analytical Centre, University of New South Wales, Sydney, Australia.
Ophthalmic Physiol Opt. 2023 Mar;43(2):273-283. doi: 10.1111/opo.13087. Epub 2023 Jan 2.
Dendritic cells (DC) play a crucial role in ocular surface defence. DC can be visualised in vivo by confocal microscopy but have not yet been fully characterised in humans. This study investigated the diurnal variation, topographical distribution and repeatability of DC density and morphology measurements.
In vivo confocal microscopy (IVCM) was conducted on 20 healthy participants (mean age 32.7 ± 6.4 years, 50% female) at baseline and repeated after 30 minutes, 2, 6 and 24 h. Images were captured at the corneal centre, inferior whorl, corneal periphery, limbus and bulbar conjunctiva. DC were counted manually, and their morphology was assessed for cell body size, presence of dendrites, and presence of long and thick dendrites. Mixed-model analysis, non-parametric analyses, Bland and Altman plots, coefficient of repeatability (CoR) and kappa were used.
There were no significant changes in DC density (p ≥ 0.74) or morphology (p > 0.07) at any location over the 24-h period. The highest DC density was observed at the corneal limbus followed by the peripheral cornea (p < 0.001), with the lowest density at the corneal centre, inferior whorl and bulbar conjunctiva. Most DC at the corneal periphery, limbus and bulbar conjunctiva had larger cell bodies compared with the corneal centre (p ≤ 0.01), and the presence of long dendrites was observed mostly at non-central locations. Day-to-day CoR for DC density ranged from ±28.1 cells/mm at the corneal centre to ±56.4 cells/mm at the limbus. Day-to-day agreement of DC morphology determined by kappa ranged from 0.5 to 0.95 for cell body size, 0.60 to 0.95 for presence of dendrites, and 0.55 to 0.80 for the presence of long dendrites at various locations.
No diurnal changes are apparent in corneal or conjunctival DC. Substantial topographical differences exist in DC density and morphology. IVCM provides good repeatability of DC density and acceptable agreement of DC morphology.
树突状细胞（DC）在眼表防御中起着至关重要的作用。通过共聚焦显微镜可以在体内观察到 DC，但尚未在人类中对其进行充分的特征描述。本研究旨在调查 DC 密度和形态测量的昼夜变化、分布差异和重复性。
对 20 名健康受试者（平均年龄 32.7±6.4 岁，50%为女性）进行共聚焦显微镜检查，在基线和 30 分钟、2、6 和 24 小时后重复检查。图像采集于角膜中央、下穹窿、角膜周边、角膜缘和球结膜。手动计数 DC，并评估其细胞体大小、树突存在情况以及长而粗树突的存在情况。采用混合模型分析、非参数分析、Bland 和 Altman 图、重复性系数（CoR）和kappa 分析。
在 24 小时内，各部位的 DC 密度（p≥0.74）或形态（p>0.07）均无显著变化。角膜缘的 DC 密度最高，其次是周边角膜（p<0.001），角膜中央、下穹窿和球结膜的密度最低。与角膜中央相比，角膜周边、角膜缘和球结膜的大多数 DC 细胞体较大（p≤0.01），并且长树突主要出现在非中央位置。角膜中央的 DC 密度日间重复性 CoR 为±28.1 个/mm，而角膜缘的 CoR 为±56.4 个/mm。kappa 分析显示，各部位 DC 形态的日间一致性为细胞体大小 0.5 至 0.95，树突存在 0.60 至 0.95，长树突存在 0.55 至 0.80。
角膜和结膜的 DC 无昼夜变化。DC 密度和形态存在显著的地域差异。共聚焦显微镜可重复性好，对 DC 形态的一致性评估可接受。
