scholarly journals Eye tracking-based estimation and compensation of chromatic offsets for multi-wavelength retinal microstimulation with foveal cone precision

2019 ◽  
Author(s):  
Niklas Domdei ◽  
Michael Linden ◽  
Jenny L. Reiniger ◽  
Frank G. Holz ◽  
Wolf M. Harmening
Keyword(s):  
Adaptive Optics ◽  
Imaging System ◽  
Chromatic Dispersion ◽  
Photoreceptor Cells ◽  
Chromatic Aberration ◽  
Eye Position ◽  
Calibration Data ◽  
Multi Wavelength ◽  
In Vivo Testing

AbstractMulti-wavelength ophthalmic imaging and stimulation of photoreceptor cells requires consideration of chromatic dispersion of the eye, manifesting in longitudinal and transverse chromatic aberrations. Current image-based techniques to measure and correct transverse chromatic aberration (TCA) and the resulting transverse chromatic offset (TCO) in an adaptive optics retinal imaging system are precise, but lack compensation of small but significant shifts in eye position occurring during in vivo testing. Here we present a method that requires only a single measurement of TCO during controlled movements of the eye to map retinal chromatic image shifts to the image space of a pupil camera. After such calibration, TCO can be compensated by continuously monitoring eye position during experimentation and by interpolating correction vectors from a linear fit to the calibration data. The average change rate of TCO per head shift and the correlation between Kappa and the individual foveal TCA are close to the expectations based on a chromatic eye model. Our solution enables continuous correction of TCO with high spatial precision and avoids high light intensities required for re-measuring TCO after eye position changes, which is necessary for foveal cone-targeted psychophysical experimentation.

scholarly journals Statistical analysis of ocular monochromatic aberrations in Chinese population for adaptive optics ophthalmoscope design

2017 ◽  
Vol 10 (01) ◽  
pp. 1650038 ◽  
Author(s):  
Junlei Zhao ◽  
Fei Xiao ◽  
Jian Kang ◽  
Haoxin Zhao ◽  
Yun Dai ◽  
...  
Keyword(s):  
High Resolution ◽  
Adaptive Optics ◽  
Chinese Population ◽  
Imaging System ◽  
Retinal Imaging ◽  
Clinical Environment ◽  
Monochromatic Aberrations ◽  
Imaging System Design ◽  
Healthy Eyes

It is necessary to know the distribution of the Chinese eye’s aberrations in clinical environment to guide high-resolution retinal imaging system design for large Chinese population application. We collected the monochromatic wave aberration of 332 healthy eyes and 344 diseased eyes in Chinese population across a 6.0-mm pupil. The aberration statistics of Chinese eyes including healthy eyes and diseased eyes were analyzed, and some differences of aberrations between the Chinese and European race were concluded. On this basis, the requirement for adaptive optics (AO) correction of the Chinese eye’s monochromatic aberrations was analyzed. The result showed that a stroke of 20[Formula: see text][Formula: see text]m and ability to correct aberrations up to the 8th Zernike order were needed for reflective wavefront correctors to achieve near diffraction-limited imaging in both groups for a reference wavelength of 550[Formula: see text]nm and a pupil diameter of 6.0[Formula: see text]mm. To verify the analysis mentioned above, an AO flood-illumination system was established, and high-resolution retinal imaging in vivo was achieved for Chinese eye including both healthy and diseased eyes.

scholarly journals Emulated retinal image capture (ERICA) to test, train and validate processing of retinal images

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Laura K. Young ◽  
Hannah E. Smithson
Keyword(s):  
Adaptive Optics ◽  
Retinal Image ◽  
Imaging System ◽  
Ground Truth ◽  
Learning Approaches ◽  
Image Capture ◽  
Ground Truth Data ◽  
Cone Mosaic ◽  
Synthetic Images

AbstractHigh resolution retinal imaging systems, such as adaptive optics scanning laser ophthalmoscopes (AOSLO), are increasingly being used for clinical research and fundamental studies in neuroscience. These systems offer unprecedented spatial and temporal resolution of retinal structures in vivo. However, a major challenge is the development of robust and automated methods for processing and analysing these images. We present ERICA (Emulated Retinal Image CApture), a simulation tool that generates realistic synthetic images of the human cone mosaic, mimicking images that would be captured by an AOSLO, with specified image quality and with corresponding ground-truth data. The simulation includes a self-organising mosaic of photoreceptors, the eye movements an observer might make during image capture, and data capture through a real system incorporating diffraction, residual optical aberrations and noise. The retinal photoreceptor mosaics generated by ERICA have a similar packing geometry to human retina, as determined by expert labelling of AOSLO images of real eyes. In the current implementation ERICA outputs convincingly realistic en face images of the cone photoreceptor mosaic but extensions to other imaging modalities and structures are also discussed. These images and associated ground-truth data can be used to develop, test and validate image processing and analysis algorithms or to train and validate machine learning approaches. The use of synthetic images has the advantage that neither access to an imaging system, nor to human participants is necessary for development.

scholarly journals High-resolution two-photon transcranial imaging of brain using direct wavefront sensing

2020 ◽  
Author(s):  
Congping Chen ◽  
Zhongya Qin ◽  
Sicong He ◽  
Shaojun Liu ◽  
Shun-Fat Lau ◽  
...  
Keyword(s):  
High Resolution ◽  
Adaptive Optics ◽  
Pyramidal Neurons ◽  
Imaging System ◽  
Superficial Layer ◽  
Wavefront Sensing ◽  
Two Photon Microscopy ◽  
Two Photon ◽  
Transcranial Imaging

AbstractImaging of the brain in its native state at high resolution poses major challenges to visualization techniques. Two-photon microscopy integrated with the thinned-skull or optical clearing skull technique provides a minimally invasive tool for in vivo imaging of the cortex of mice without activating immune response and inducing brain injury. However, the imaging contrast and resolution are severely compromised by the optical heterogeneity of the skull, limiting the imaging depth to the superficial layer. Here, we develop adaptive optics two-photon microscopy for high-resolution transcranial imaging of layer 5 pyramidal neurons up to 700 μm below pia in living mice. In particular, an optimized configuration of imaging system and new wavefront sensing algorithm are proposed for accurate correction for the aberrations induced by the skull window and brain tissue. We investigated microglia-plaque interaction in living brain of Alzheimer’s disease and demonstrated high-precision laser dendrotomy and single-spine ablation.

A High-resolution Multi-wavelength Simultaneous Imaging System with Solar Adaptive Optics

2017 ◽  
Vol 154 (4) ◽  
pp. 143 ◽  
Author(s):  
Changhui Rao ◽  
Lei Zhu ◽  
Naiting Gu ◽  
Xuejun Rao ◽  
Lanqiang Zhang ◽  
...  
Keyword(s):  
High Resolution ◽  
Adaptive Optics ◽  
Imaging System ◽  
Simultaneous Imaging ◽  
Multi Wavelength

scholarly journals Multi-wavelength fluorescence imaging with a da Vinci Firefly—a technical look behind the scenes

2020 ◽  
Author(s):  
Philippa Meershoek ◽  
Gijs H. KleinJan ◽  
Danny M. van Willigen ◽  
Kevin P. Bauwens ◽  
Silvia J. Spa ◽  
...  
Keyword(s):  
Fluorescence Imaging ◽  
Da Vinci ◽  
Imaging System ◽  
Photophysical Properties ◽  
Detection Sensitivity ◽  
Guided Surgery ◽  
Camera Systems ◽  
Multi Wavelength ◽  
Da Vinci Si

AbstractThe field of fluorescence-guided surgery builds on colored fluorescent tracers that have become available for different clinical applications. Combined use of complementary fluorescent emissions can allow visualization of different anatomical structures (e.g. tumor, lymphatics and nerves) in the same patient. With the aim to assess the requirements for multi-color fluorescence guidance under in vivo conditions, we thoroughly characterized two FDA-approved laparoscopic Firefly camera systems available on the da Vinci Si or da Vinci Xi surgical robot. In this process, we studied the cameras’ performance with respect to the photophysical properties of the FDA-approved dyes Fluorescein and ICG. Our findings indicate that multi-wavelength fluorescence imaging of Fluorescein and ICG is possible using clinical-grade fluorescence laparoscopes, but critical factors for success include the photophysical dye properties, imaging system performance and the amount of accumulated dye. When comparing the camera performance, the Xi system provided more effective excitation (adaptions in the light source) and higher detection sensitivity (chip-on-a-tip and/or enhanced image processing) for both Fluorescein and ICG. Both systems can readily be used for multi-wavelength fluorescence imaging of Fluorescein and ICG under clinically relevant conditions. With that, another step has been made towards the routine implementation of multi-wavelength image-guided surgery concepts.

scholarly journals ERICA: Emulated Retinal Image CApture - A tool for testing, training and validating retinal image processing methods

2021 ◽  
Author(s):  
Laura K Young ◽  
Hannah E Smithson
Keyword(s):  
Image Processing ◽  
Adaptive Optics ◽  
Retinal Image ◽  
Imaging System ◽  
Ground Truth ◽  
Learning Approaches ◽  
Image Capture ◽  
Ground Truth Data ◽  
Synthetic Images

ABSTRACTHigh resolution retinal imaging systems, such as adaptive optics scanning laser ophthalmoscopes (AOSLO), are increasingly being used for clinical and fundamental studies in neuroscience. These systems offer unprecedented spatial and temporal resolution of retinal structures in vivo. However, a major challenge is the development of robust and automated methods for processing and analysing these images. We present ERICA (Emulated Retinal Image CApture), a simulation tool that generates realistic synthetic images of the human cone mosaic, mimicking images that would be captured by an AOSLO, with specified image quality and with corresponding ground truth data. The simulation includes a self-organising mosaic of photoreceptors, the eye movements an observer might make during image capture, and data capture through a real system incorporating diffraction, residual optical aberrations and noise. The retinal photoreceptor mosaics generated by ERICA have a similar packing geometry to human retina, as determined by expert labelling of AOSLO images of real eyes. In the current implementation ERICA outputs convincingly realistic en face images of the cone photoreceptor mosaic but extensions to other imaging modalities and structures are also discussed. These images and associated ground-truth data can be used to develop, test and validate image processing and analysis algorithms or to train and validate machine learning approaches. The use of synthetic images has the advantage that neither access to an imaging system, nor to human participants is necessary for development.

scholarly journals Cone photoreceptor dysfunction in retinitis pigmentosa revealed by optoretinography

2021 ◽  
Vol 118 (47) ◽  
pp. e2107444118
Author(s):  
Ayoub Lassoued ◽  
Furu Zhang ◽  
Kazuhiro Kurokawa ◽  
Yan Liu ◽  
Marcel T. Bernucci ◽  
...  
Keyword(s):  
Retinitis Pigmentosa ◽  
Adaptive Optics ◽  
Vision Loss ◽  
Photoreceptor Cells ◽  
Segment Length ◽  
Cone Photoreceptor ◽  
Cone Cells ◽  
Common Group ◽  
Cone Density

Retinitis pigmentosa (RP) is the most common group of inherited retinal degenerative diseases, whose most debilitating phase is cone photoreceptor death. Perimetric and electroretinographic methods are the gold standards for diagnosing and monitoring RP and assessing cone function. However, these methods lack the spatial resolution and sensitivity to assess disease progression at the level of individual photoreceptor cells, where the disease originates and whose degradation causes vision loss. High-resolution retinal imaging methods permit visualization of human cone cells in vivo but have only recently achieved sufficient sensitivity to observe their function as manifested in the cone optoretinogram. By imaging with phase-sensitive adaptive optics optical coherence tomography, we identify a biomarker in the cone optoretinogram that characterizes individual cone dysfunction by stimulating cone cells with flashes of light and measuring nanometer-scale changes in their outer segments. We find that cone optoretinographic responses decrease with increasing RP severity and that even in areas where cone density appears normal, cones can respond differently than those in controls. Unexpectedly, in the most severely diseased patches examined, we find isolated cones that respond normally. Short-wavelength–sensitive cones are found to be more vulnerable to RP than medium- and long-wavelength–sensitive cones. We find that decreases in cone response and cone outer-segment length arise earlier in RP than changes in cone density but that decreases in response and length are not necessarily correlated within single cones.

New Aspects in the Design of Electron Optical Magnification Systems

1972 ◽  
Vol 30 ◽  
pp. 606-607
Author(s):  
Willem H.J. Andersen
Keyword(s):  
Electron Microscope ◽  
Imaging System ◽  
Chromatic Aberration ◽  
Research Tool ◽  
Energy Losses ◽  
Objective Lens ◽  
Theoretical Limit ◽  
Optical Magnification ◽  
Chromatic Aberrations ◽  
High Degree

Electron microscope design, and particularly the design of the imaging system, has reached a high degree of perfection. Present objective lenses perform up to their theoretical limit, while the whole imaging system, consisting of three or four lenses, provides very wide ranges of magnification and diffraction camera length with virtually no distortion of the image. Evolution of the electron microscope in to a routine research tool in which objects of steadily increasing thickness are investigated, has made it necessary for the designer to pay special attention to the chromatic aberrations of the magnification system (as distinct from the chromatic aberration of the objective lens). These chromatic aberrations cause edge un-sharpness of the image due to electrons which have suffered energy losses in the object.There exist two kinds of chromatic aberration of the magnification system; the chromatic change of magnification, characterized by the coefficient Cm, and the chromatic change of rotation given by Cp.

Multi-mode light microscopy of microtubule assembly dynamics and chromosome movement in vivo and In vitro

1996 ◽  
Vol 54 ◽  
pp. 730-731
Author(s):  
E. D. Salmon ◽  
J. C. Waters ◽  
C. Waterman-Storer
Keyword(s):  
Imaging System ◽  
Ccd Camera ◽  
Transmitted Light ◽  
Microtubule Assembly ◽  
Live Cells ◽  
Optical Efficiency ◽  
Multiple Band ◽  
Multi Mode

We have developed a multi-mode digital imaging system which acquires images with a cooled CCD camera (Figure 1). A multiple band pass dichromatic mirror and robotically controlled filter wheels provide wavelength selection for epi-fluorescence. Shutters select illumination either by epi-fluorescence or by transmitted light for phase contrast or DIC. Many of our experiments involve investigations of spindle assembly dynamics and chromosome movements in live cells or unfixed reconstituted preparations in vitro in which photodamage and phototoxicity are major concerns. As a consequence, a major factor in the design was optical efficiency: achieving the highest image quality with the least number of illumination photons. This principle applies to both epi-fluorescence and transmitted light imaging modes. In living cells and extracts, microtubules are visualized using X-rhodamine labeled tubulin. Photoactivation of C2CF-fluorescein labeled tubulin is used to locally mark microtubules in studies of microtubule dynamics and translocation. Chromosomes are labeled with DAPI or Hoechst DNA intercalating dyes.

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