Polarization-sensitive optical coherence tomography as a tool to visualize the fiber direction of retinal nerves and peripapillary sclera

Polarization sensitive optical coherence tomography (PS-OCT) has been used to visualize the orientation of the nerves in the retinal nerve fiber layer (RNFL) and to visualize the orientation of the collagen fibers in peripapillary sclera in retinas of healthy volunteers. Optic axis orientation images clearly visualize the nerve fibers leaving the optic nerve head (ONH) in all radial directions. Sclera orientation images show that the sclera consist of two layers, an inner layer with an orientation parallel to the RNFL orientation, and a deeper layer where the collagen is circularly oriented

Polarization-sensitive optical coherence tomography as a tool to visualize the fiber direction of retinal nerves and peripapillary sclera

Polarization sensitive optical coherence tomography (PS-OCT) has been used to visualize the orientation of the nerves in the retinal nerve fiber layer (RNFL) and to visualize the orientation of the collagen fibers in peripapillary sclera in retinas of healthy volunteers. Optic axis orientation images clearly visualize the nerve fibers leaving the optic nerve head (ONH) in all radial directions. Sclera orientation images show that the sclera consist of two layers, an inner layer with an orientation parallel to the RNFL orientation, and a deeper layer where the collagen is circularly oriented

In vivo 3D determination of peripapillary scleral and retinal layer architecture using polarization-sensitive optical coherence tomography

Purpose: The purpose of this paper was to determine the architecture of the collagen fibers of the peripapillary sclera, the retinal nerve fiber layer (RNFL), and Henle’s fiber layer in vivo in 3D using polarization-sensitive optical coherence tomography (PS-OCT). Methods: Seven healthy volunteers were imaged with our in-house built PS-OCT system. PS-OCT imaging included intensity, local phase retardation, relative optic axis, and optic axis uniformity (OAxU). Differential Mueller matrix calculus was used for the first time in ocular tissues to visualize local orientations that varied with depth, incorpo-rating a correction method for the fiber orientation in preceding layers. Results: Scleral collagen fiber orientation images clearly showed an inner layer with an orientation parallel to the RNFL orientation, and a deeper layer where the collagen was circularly oriented. RNFL orientation images visualized the nerve fibers leaving the optic nerve head (ONH) in a radial pattern. The phase retardation and orientation of Henle’s fiber layer were visualized locally for the first time. Conclusions: PS-OCT successfully showed the orientation of the retinal nerve fibers, sclera, and Henle’s fiber layer, and is to the extent of our knowledge the only technique able to do so in 3D in vivo. Translational Relevance: In vivo 3D imaging of scleral collagen architecture and the retinal neural fibrous structures can improve our understanding of retinal biomechanics and structural alterations in different disease stages of myopia and glaucoma

Visualizing orientation of retinal nerves and depolarization in the choroid using polarization-sensitive optical coherence tomography (Conference Presentation)

Polarization sensitive optical coherence tomography (PS-OCT) has been used to visualize the orientation of the nerves in the retinal nerve fiber layer (RNFL) and to visualize depolarization in retinas of healthy volunteers and age-related macular degeneration (AMD) patients. Optic axis orientation images clearly visualize the nerve fibers leaving the optic nerve head (ONH) in all radial directions in healthy volunteers. Depolarization images show depolarization of the RPE and for some cases, highlight another depolarizing layer at the boundary of the choroid and sclera

Endoscopic polarization-sensitive optical coherence tomography in multiple lung diseases (Conference Presentation)

Polarization-sensitive optical coherence tomography (PS-OCT) has been used to extract polarization properties of four different diseased lungs ex vivo, including fibrotic sarcoidosis (FS), chronic obstructive pulmonary disease (COPD), fibrotic extrinsic allergic alveolitis (fibrotic EAA) and cystic fibrosis (CF). An increase in alveoli size has been observed in COPD lungs. Furthermore, an increase in birefringence signal was observed for FS and fibrotic EAA. In CF, a few areas with thick patches of birefringence occurred. The results show potential of in vivo assessment of lung fibrosis. Histology slides of all lungs were acquired, and will be used to further interpret the results

Multifunctional optical coherence tomography for endoscopic in-vivo imaging of lungs periphery in asthma patients (Conference Presentation)

We present a motorized distal scanning endoscope with an outer diameter of 1.35 mm and 52 fps rotation speed for in vivo imaging in the peripheral airways of lungs. Three lung segments of an asthma patient pre and post bronchial thermoplasty (BT) treatment were imaged. Optical coherence tomography (OCT) intensity images, attenuation coefficient (AC) images and polarization sensitive OCT (PS-OCT) images showing both birefringence, optic axis uniformity (OAxU) and optic axis (OA) orientation were extracted from the acquired data. PS-OCT endoscopy visualized airway smooth muscle layer thickness and location pre and post BT treatment as means to predict its effectiveness

Optic axis uniformity as a metric to improve the contrast of birefringent structures and analyze the retinal nerve fiber layer in polarization-sensitive optical coherence tomography

A new metric is used to improve the contrast of birefringent structures in biological tissue using polarization-sensitive optical coherence tomography. This metric, optic axis uniformity (OAxU), is based on the optic axis of birefringence and quantifies the uniformity of the optic axis direction. OAxU provides surprisingly strong contrast for fibrous structures such as muscle and the retinal nerve fiber layer (RNFL). We used OAxU for automatic segmentation of the RNFL in human eyes. From the segmentation, en face images of RNFL thickness and RNFL birefringence were created. The measured birefringence values are consistent with earlier reports