Eye diseases have always been a threat to public health worldwide. Many people suffer from various eye diseases, but there are not enough skilled ophthalmologists to meet the demand for medical care. Thus, finding a method to perform ophthalmic examinations automatically and conveniently is necessary. Although many well-designed ophthalmic diagnosis systems have been proposed to diagnose ophthalmic disorders using artificial intelligence algorithms, they tend to depend on high-quality anterior segment images to perform appropriately. In order to capture high-quality anterior segment images simply with a smartphone, we proposed a system including a semantic segmentation model and an image quality assessment method for anterior segment images. Our proposed segmentation model, namely the multi-task anterior segment image semantic segmentation (MT-ASISS) model, has a designed multitask learning network structure and achieves an accuracy of 92.63% in Dice and a processing speed of 138ms per frame on smartphones. Our anterior segment image quality assessment method, namely Mixed-Parameters Quality Assessment (MPQA) method, has an accuracy of 92.6% in mean average precision (mAP). The system can help reduce the demand for professional image collecting equipment, share the burden of choosing satisfactory images manually and improve the efficiency of acquiring anterior segment images.
Regenerative therapies such as stem cell therapies are an area of active investigation that will likely play an important role in the future to improve vision loss from retinal diseases including macular degeneration and retinitis pigmentosa. It is important to visualize these cells after administration to determine their fate and effect. In this study, an advanced non-invasive photoacoustic microscopy (PAM) and optical coherence tomography (OCT) imaging system was developed to monitor cells in vivo. To boost the sensitivity of PAM and OCT, novel ultrapure functionalized chain-like gold nanoparticle (CGNP) clusters were synthesized and cultured into a precursor human retinal pigment epithelial cell line with differentiated properties (ARPE-19) cells. The fabricated CGNP clusters have redshifted plasmonic peak absorption from 520nm to 650nm, resulting in reduced background signal from hemoglobin. The position of cells following subretinal injection into the rabbit retina having laser injury is selectively tracked longitudinally in vivo using integrated photoacoustic microscopy (PAM) and OCT over 3 months in 3 rabbits. PAM images obtained at two different optical wavelengths of 578 nm and 650 nm were overlaid on the same image plane and on the OCT image allowed to distinguish transplanted cells from the adjacent native choroidal vessels and track the migration of the cells over time. Quantification of PAM and OCT signals illustrated that the PAM signal increased by 30-fold, and OCT signal increased by 180 %. Histological analysis confirmed that ARPE-19 cells migrated to the injured sites and correlated with the location noted on the PAM/OCT imaging. This work provides a comprehensive imaging and nanoparticle system that could be used for labeling and tracking of cell-based regenerative therapies.
Photoacoustic microscopy (PAM) is a non-invasive and hybrid optical imaging technique that has a potential to visualize chorioretinal vasculature in vivo. The capability of PAM can be extended to better visualize the dynamic changes of the vasculature network in the retina when it is combined with another imaging modality such as fluorescence microscopy or OCT. In this study, an integrated PAM and OCT has been developed to identify the local tissue damage during laserinduced photocoagulation on major choroidal vessels. Choroidal lesion was induced using a high power green light laser at 532 nm with millisecond pulse duration in eight New Zealand rabbits. Each rabbit eye was irradiated for 0.5 s at a laser power of 750 mW and spot size of 100 μm. Six laser burn positions were created on each eye. At each laser burn, twenty shots of the laser were applied. Multimodal PAM, OCT, fundus, and FA were used to monitor thermal lesion at different time points (days 0, 1, 3, 5, 7, 14, 21, and 28) after photocoagulation. All thermal lesions were clearly identified with high resolution using PAM. In addition, the PAM images exhibited dynamic changes of density and morphology of choroidal vasculature. The OCT images provided visualization of the cross-sectional structure of retinal tissues and the location of thermal lesion. Multimodal PAM and OCT can provide a feasible tool for evaluation and monitoring of damaged tissues and the microvasculature of the retina.
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