Zhang Pengfei, Goswami Mayank, Zam Azhar, Pugh Edward N, Zawadzki Robert J
Opt Lett. 2015 Dec 15;40(24):5830-3. doi: 10.1364/OL.40.005830.
Scanning laser ophthalmoscopy (SLO) employs the eye's optics as a microscope objective for retinal imaging in vivo. The mouse retina has become an increasingly important object for investigation of ocular disease and physiology with optogenetic probes. SLO imaging of the mouse eye, in principle, can achieve submicron lateral resolution thanks to a numerical aperture (NA) of ∼0.5, about 2.5 times larger than that of the human eye. In the absence of adaptive optics, however, natural ocular aberrations limit the available optical resolution. The use of a contact lens, in principle, can correct many aberrations, permitting the use of a wider scanning beam and, thus, achieving greater resolution then would otherwise be possible. In this Letter, using an SLO equipped with a rigid contact lens, we report the effect of scanning beam size on the lateral resolution of mouse retinal imaging. Theory predicts that the maximum beam size full width at half-maximum (FWHM) that can be used without any deteriorating effects of aberrations is ∼0.6 mm. However, increasing the beam size up to the diameter of the dilated pupil is predicted to improve lateral resolution, though not to the diffraction limit. To test these predictions, the dendrites of a retinal ganglion cell expressing YFP were imaged, and transverse scans were analyzed to quantify the SLO system resolution. The results confirmed that lateral resolution increases with the beam size as predicted. With a 1.3 mm scanning beam and no high-order aberration correction, the lateral resolution is ∼1.15 μm, superior to that achievable by most human AO-SLO systems. Advantages of this approach include stabilization of the mouse eye and simplified optical design.
扫描激光检眼镜（SLO）利用眼睛的光学系统作为显微镜物镜，用于体内视网膜成像。小鼠视网膜已成为使用光遗传学探针研究眼部疾病和生理学的一个越来越重要的对象。原则上，由于约0.5的数值孔径（NA），小鼠眼睛的SLO成像可以实现亚微米级的横向分辨率，这大约是人眼数值孔径的2.5倍。然而，在没有自适应光学的情况下，自然的眼部像差会限制可用的光学分辨率。原则上，使用隐形眼镜可以校正许多像差，允许使用更宽的扫描光束，从而实现比其他情况下更高的分辨率。在本信函中，我们使用配备刚性隐形眼镜的SLO，报告了扫描光束大小对小鼠视网膜成像横向分辨率的影响。理论预测，在没有像差恶化影响的情况下可以使用的最大光束大小，即半高全宽（FWHM）约为0.6毫米。然而，预计将光束大小增加到散瞳直径，虽然不会达到衍射极限，但会提高横向分辨率。为了验证这些预测，对表达黄色荧光蛋白（YFP）的视网膜神经节细胞的树突进行成像，并分析横向扫描以量化SLO系统分辨率。结果证实，横向分辨率如预测的那样随着光束大小的增加而提高。使用1.3毫米的扫描光束且不进行高阶像差校正时，横向分辨率约为1.15微米，优于大多数人眼自适应光学扫描激光检眼镜（AO-SLO）系统所能达到的分辨率。这种方法的优点包括稳定小鼠眼睛和简化光学设计。
