Morgan Jessica I W, Dubra Alfredo, Wolfe Robert, Merigan William H, Williams David R
University of Rochester, Center for Visual Science, Rochester, New York 14627, USA.
Invest Ophthalmol Vis Sci. 2009 Mar;50(3):1350-9. doi: 10.1167/iovs.08-2618. Epub 2008 Oct 24.
Retinal pigment epithelial (RPE) cells are critical for the health of the retina, especially the photoreceptors. A recent study demonstrated that individual RPE cells could be imaged in macaque in vivo by detecting autofluorescence with an adaptive optics scanning laser ophthalmoscope (AOSLO). The current study extended this method to image RPE cells in fixating humans in vivo and to quantify the RPE mosaic characteristics in the central retina of normal humans and macaques.
The retina was imaged simultaneously with two light channels in a fluorescence AOSLO; one channel was used for reflectance imaging of the cones while the other detected RPE autofluorescence. The excitation light was 568 nm, and emission was detected over a 40-nm range centered at 624 nm. Reflectance frames were registered to determine interframe eye motion, the motion was corrected in the simultaneously recorded autofluorescence frames, and the autofluorescence frames were averaged to give the final RPE mosaic image.
In vivo imaging demonstrated that with increasing eccentricity, RPE cell density, and mosaic regularity decreased, whereas RPE cell size and spacing increased. Repeat measurements of the same retinal location 42 days apart showed the same RPE cells and distribution.
The RPE cell mosaic has been resolved for the first time in alert fixating human subjects in vivo using AOSLO. Mosaic analysis provides a quantitative database for studying normal and diseased RPE in vivo. This technique will allow longitudinal studies to track disease progression and assess treatment efficacy in patients and animal models of retinal disease.
视网膜色素上皮（RPE）细胞对视网膜尤其是光感受器的健康至关重要。最近一项研究表明，通过自适应光学扫描激光检眼镜（AOSLO）检测自发荧光，可在猕猴体内对单个RPE细胞进行成像。本研究将该方法扩展至对注视状态下的人类活体RPE细胞进行成像，并量化正常人和猕猴中央视网膜的RPE镶嵌特征。
在荧光AOSLO中用两个光通道同时对视网膜成像；一个通道用于视锥细胞的反射成像，另一个通道检测RPE自发荧光。激发光为568nm，在以624nm为中心的40nm范围内检测发射光。配准反射图像帧以确定帧间眼动，在同时记录的自发荧光图像帧中校正该运动，并对自发荧光图像帧求平均值以得到最终的RPE镶嵌图像。
活体成像显示，随着偏心度增加，RPE细胞密度和镶嵌规则性降低，而RPE细胞大小和间距增加。相隔42天对同一视网膜位置进行的重复测量显示RPE细胞及其分布相同。
首次使用AOSLO在清醒注视的人类受试者体内解析了RPE细胞镶嵌。镶嵌分析为体内研究正常和患病RPE提供了定量数据库。该技术将允许进行纵向研究以跟踪疾病进展并评估视网膜疾病患者和动物模型的治疗效果。
