We present the first full-field optical coherence tomography (FFOCT) device capable of imaging of the human cornea. We obtained images of the epithelial structures, Bowman's layer, sub-basal nerve plexus (SNP), anterior and posterior stromal keratocytes, stromal nerves, Descemet's membrane and endothelial cells with visible nuclei. Images were acquired with a high lateral resolution of 1.7 µm and relatively large field-of-view of 1.26 mm x 1.26 mm - a combination, which, to the best of our knowledge, has not been possible with other human eye imaging methods. The latter together with a contactless operation, make FFOCT a promising candidate for becoming a new tool in ophthalmic diagnostics.

et al.. Probing dynamic processes in the eye at multiple spatial and temporal scales with multimodal full field OCT. Abstract:We describe recent technological progress in multimodal en face full-field optical coherence tomography that has allowed detection of slow and fast dynamic processes in the eye. We show that by combining static, dynamic and fluorescence contrasts we can achieve label-free high-resolution imaging of the retina and anterior eye with temporal resolution from milliseconds to several hours, allowing us to probe biological activity at subcellular scales inside 3D bulk tissue. Our setups combine high lateral resolution over a large field of view with acquisition at several hundreds of frames per second which make it a promising tool for clinical applications and biomedical studies. Its contactless and non-destructive nature is shown to be effective for both following in vitro sample evolution over long periods of time and for imaging of the human eye in vivo.

We show that with spatially incoherent illumination, the point spread function width of an imaging interferometer like that used in full-field optical coherence tomography (FFOCT) is almost insensitive to aberrations that mostly induce a reduction of the signal level without broadening. This is demonstrated by comparison with traditional scanning OCT and wide-field OCT with spatially coherent illuminations. Theoretical analysis, numerical calculation as well as experimental results are provided to show this specific merit of incoherent illumination in full-field OCT. To the best of our knowledge, this is the first time that such result has been demonstrated.

Bcakground：Meibography is a non-contact imaging technique used by ophthalmologists and eye care practitioners to acquire information on the characteristics of meibomian glands. One of its most important applications is to assist in the evaluation and diagnosis of meibomian gland dysfunction (MGD). While artificial qualitative analysis of meibography images could lead to low repeatability and efficiency, automated and quantitative evaluation would greatly benefit the image analysis process. Moreover, since the morphology and function of meibomian glands varies at different MGD stages, multi-parametric analysis offering more comprehensive information could help in discovering subtle changes of meibomian glands during MGD progression. Therefore, automated and multi-parametric objective analysis of meibography images is highly demanded. Methods:The algorithm is developed to perform multi-parametric analysis of meibography images with fully automatic and repeatable segmentation based on image contrast enhancement and noise reduction. The full architecture can be divided into three steps: (1) segmentation of the tarsal conjunctiva area as the region of interest (ROI); (2) segmentation and identification of glands within the ROI; and (3) quantitative multi-parametric analysis including newly defined gland diameter deformation index (DI), gland tortuosity index (TI), and glands signal index (SI). To evaluate the performance of the automated algorithm, the similarity index (𝑘) and the segmentation error including the false positive rate (𝑟 𝑃 ) and the false negative rate (𝑟 𝑁 ) are calculated between the manually defined ground truth and the automatic segmentations of both the ROI and meibomian glands of 15 typical meibography images. The feasibility of the algorithm is demonstrated in analyzing typical meibograhy images. Results:The results of the performance evaluation between the manually defined ground truth and the automatic segmentations are as following: for ROI segmentation, the similarity index 𝑘 = 0.94 ± 0.02, the false positive rate 𝑟 𝑃 = 6.02 ± 2.41%, and the false negative rate 𝑟 𝑁 = 6.43 ± 1.98%; for meibomian glands segmentation, the similarity index 𝑘 = 0.87 ± 0.01, the false positive rate 𝑟 𝑃 = 4.35% ± 1.50%, and the false negative rate 𝑟 𝑁 = 18.61% ± 1.54%.The algorithm has been successfully applied to process typical meibography images acquired from subjects at different meibomian gland healthy status, providing the glands area ratio GA, the gland length 𝐿, gland width 𝐷, gland diameter deformation index 𝐷𝐼, gland tortuosity index 𝑇𝐼 and glands signal index SI.Conclusions: A fully automated algorithm has been developed showing high similarity with moderate segmentation errors for meibography image segmentation compared with the manual approach, offering multiple parameters to quantify the morphology and function of meibomian glands for objective evaluation of meibography image.

As the lateral resolution of full-field optical coherence tomography (FFOCT) with spatially incoherent illumination has been shown to be insensitive to aberrations, we demonstrate high-resolution en face FFOCT retinal imaging without wavefront correction in the human eye in vivo for the first time, to our knowledge. A combination of FFOCT with spectraldomain OCT (SDOCT) is applied for real-time matching of the optical path lengths (OPLs) of FFOCT. Through the realtime cross-sectional SDOCT images, the OPL of the FFOCT reference arm is matched with different retinal layers in the FFOCT sample arm. Thus, diffraction-limited FFOCT images of multiple retinal layers are acquired at both the near periphery and the fovea. The en face FFOCT retinal images reveal information about various structures, such as the nerve fiber orientation, the blood vessel distribution, and the photoreceptor mosaic. During its 25 years of development, optical coherence tomography (OCT) has become a powerful imaging modality in biomedical and clinical studies [1,2]. It has achieved great success in ophthalmology [3], especially in retinal imaging for which it has been entitled the "virtual biopsy" for human retina [4]. Compared with typical retinal imaging modalities like fundus cameras [5] or scanning laser ophthalmoscopy (SLO) [6], in which axial resolution is limited by the finite size of the eye's pupil, OCT offers much higher axial sectioning, as the lateral and axial resolutions are decoupled. The high-resolution cross-sectional depth exploration of the retinal layers offers important information about pathologies for early diagnosis of disease and for tracing disease evolution [7][8][9]. While doctors are capable of interpreting crosssectional OCT slices, there is nevertheless a need for en face views, as shown by the continued use of en face techniques such as fundus cameras or SLO. Thanks to the speed improvement, OCT systems can provide en face retinal images by doing real-time 3Dimaging [10][11][12]. Nevertheless, due to the requirement of large depth of focus, low NA is typically used in traditional OCT, resulting in relatively low spatial resolution compared with high-NA systems. To ensure high transverse resolution, en face flying spot OCT has been applied for human retinal imaging, which achieves retinal en face images with transverse scanning [13,14]. To be able to realize close to diffraction-limited lateral resolution in OCT retinal imaging, complex hardware adaptive optics (AO) [15][16][17][18][19] or computational AO [20][21][22] would also be needed to correct the aberrations induced by the imperfections of the cornea and lens in the anterior chamber.Full-field OCT (FFOCT) is a kind of time-domain en face parallel OCT that takes images perpendicular to the optical axis without scanning. By using high-NA microscope objectives in a Linnik interferometer, FFOCT is able to achieve standard microscope spatial resolution [23]. With spatially incoherent illumination, cross talk is severely inhibited in FFOCT compared with wide-...