Pregnancy induces retinal microvascular changes indicating cardio-metabolic stress.

We performed longitudinal examinations of the arterial retinal microvasculature using Adaptive Optics Retinal Imaging in a 30-year-old healthy woman with twin pregnancy from the 23rd week of gestation (wog) to three days postpartum. Two blinded graders recorded the average wall-to-lumen ratio (WLR) of the examined retinal artery. There was a significant increase in the mean WLR over the course of pregnancy followed by a decreasing WLR from the 37th wog.

Assessment of retinal vein pulsation through video-ophthalmoscopy and simultaneous biosignals acquisition.

The phenomenon of retinal vein pulsation is still not a deeply understood topic in retinal hemodynamics. In this paper, we present a novel hardware solution for recording retinal video sequences and physiological signals using synchronized acquisition, we apply the photoplethysmographic principle for the semi-automatic processing of retinal video sequences and we analyse the timing of the vein collapse within the cardiac cycle using of an electrocardiographic signal (ECG). We measured the left eyes of healthy subjects and determined the phases of vein collapse within the cardiac cycle using a principle of photoplethysmography and a semi-automatic image processing approach.

Comprehensive automatic processing and analysis of adaptive optics flood illumination retinal images on healthy subjects.

This work presents a novel fully automated method for retinal analysis in images acquired with a flood illuminated adaptive optics retinal camera (AO-FIO). The proposed processing pipeline consists of several steps: First, we register single AO-FIO images in a montage image capturing a larger retinal area. The registration is performed by combination of phase correlation and the scale-invariant feature transform method.

Multispectral retinal video-ophthalmoscope with fiber optic illumination.

Multispectral imaging is used in various applications including astronomy, industry and agriculture. In retinal imaging, the single-shot multispectral image stack is typically acquired and analyzed. This multispectral analysis can provide information on various structural or metabolic properties.

Tuneable in-situ nanoCT workflow using FIB/SEM.

Inspired by the standard computed tomography, a new method of 3D X-ray imaging embedded in FIB-SEM microscope is proposed. The unique combination of TEM-like specimen stage enabling in lens STEM detection (referred to as CompuStage), nanomanipulator (referred to as EasyLift) facilitating in-situ sample transfer from bulk sample to TEM-like stage and pixelated in-situ Timepix X-ray detector in Helios G4 FX FIB-SEM system offers an unprecedented workflow. Motivated by common circular CT scan known from microCT world, the object under study is placed on CompuStage rod which enables two possible rotation (in TEM/SEM terminology called tilt) movements - α-tilt - rotation of the CompuStage rod around its axis, and β-tilt - rotation around axis perpendicular to CompuStage rod.

Estimation of Time Delay Between Artery and Vein Pulsation using Experimental Video-Ophthalmoscope.

The fundus observation by ophthalmoscope is a non-invasive approach for diagnosis of various retinal diseases. The vein and artery pulsation are usually clearly apparent on fundus and might be also important for medical practice. Thus our method focuses on these changes and analyzes the time delay between the pulsation signal detected in the vein and the artery region.