scholarly journals Dual-Channel Spectral Domain Optical Coherence Tomography Based on a Single Spectrometer Using Compressive Sensing

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 4006 ◽  
Author(s):  
Luying Yi ◽  
Liqun Sun ◽  
Mingli Zou ◽  
Bo Hou
Keyword(s):  
Optical Coherence Tomography ◽  
Compressive Sensing ◽  
Spectral Resolution ◽  
Single Channel ◽  
Optical Coherence ◽  
Channel System ◽  
Dual Channel ◽  
Imaging Depth ◽  
Imaging Speed ◽  
Sd Oct

Dual-channel spectral domain optical coherence tomography (SD-OCT) is one of the effective methods for improving imaging depth and imaging speed. In this paper, we design a dual-channel SD-OCT system based on a single spectrometer that can operate in two modes: (1) Increasing imaging speed and (2) expanding imaging depth. An optical path offset is preintroduced between the two channels to separate the two-channel data. However, this offset increases the requirement for the spectral resolution of the spectrometer in mode (1), so compressive sensing (CS) technology is used herein to overcome this problem. Consequently, in mode (1), when the spectral resolution of the spectrometer is the same as that used in the single-channel system, we use a dual-channel SD-OCT system combined with CS technology to double the imaging speed. In mode (2), when the spectral resolution of the spectrometer is only half of that used in a single-channel system, the imaging depth can be nearly doubled. We demonstrate the feasibility and effectiveness of the method proposed in this work by imaging a mirror, a fish fin, a fish eye, and an onion.

scholarly journals Spectral Domain Optical Coherence Tomography Imaging Performance Improvement Based on Field Curvature Aberration-Corrected Spectrometer

2020 ◽  
Vol 10 (10) ◽  
pp. 3657
Author(s):  
Seung Seok Lee ◽  
Woosub Song ◽  
Eun Seo Choi
Keyword(s):  
Optical Coherence Tomography ◽  
Spectral Domain ◽  
Optical Coherence ◽  
Modulation Transfer ◽  
Field Curvature ◽  
Spatial Frequencies ◽  
Oct Imaging ◽  
Imaging Depth ◽  
Imaging Performance ◽  
Sd Oct

We designed and fabricated a telecentric f-theta imaging lens (TFL) to improve the imaging performance of spectral domain optical coherence tomography (SD-OCT). By tailoring the field curvature aberration of the TFL, the flattened focal surface was well matched to the detector plane. Simulation results showed that the spot in the focal plane fitted well within a single pixel and the modulation transfer function at high spatial frequencies showed higher values compared with those of an achromatic doublet imaging lens, which are commonly used in SD-OCT spectrometers. The spectrometer using the TFL had an axial resolution of 7.8 μm, which was similar to the theoretical value of 6.2 μm. The spectrometer was constructed so that the achromatic doublet lens was replaced by the TFL. As a result, the SD-OCT imaging depth was improved by 13% (1.85 mm) on a 10 dB basis in the roll-off curve and showed better sensitivity at the same depth. The SD-OCT images of a multi-layered tape and a human palm proved that the TFL was able to achieve deeper imaging depth and better contrast. This feature was seen very clearly in the depth profile of the image. SD-OCT imaging performance can be improved simply by changing the spectrometer’s imaging lens. By optimizing the imaging lens, deeper SD-OCT imaging can be achieved with improved sensitivity.

scholarly journals Spectral-domain optical coherence tomography for evaluating palisades of Vogt in ocular surface disorders with limbal involvement

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ying-Yi Chen ◽  
Yi-Chen Sun ◽  
Chia-Ying Tsai ◽  
Hsiao-Sang Chu ◽  
Jo-Hsuan Wu ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Ocular Surface ◽  
Spectral Domain ◽  
Optical Coherence ◽  
Slit Lamp ◽  
Ocular Rosacea ◽  
Unilateral Disease ◽  
Healthy Eyes ◽  
Slit Lamp Biomicroscopy ◽  
Sd Oct

AbstractSpectral-domain optical coherence tomography (SD-OCT) has been used to observe the morphology of the palisades of Vogt (POV) with satisfactory resolutions. In this study, we used SD-OCT to examine the microstructure of the POV in ocular surface disorders with limbal involvement. We detect subclinical limbal pathologies based on five parameters, including (1) decreased epithelial thickness, (2) loss of the sharp stromal tip, (3) loss of the smooth epithelial-stromal interface, (4) dilated stromal vessels, and (5) decreased POV density. Eighteen eyes of 10 patients with advancing wavelike epitheliopathy (AWE) and 15 eyes of 9 patients with phlyctenular keratitis/ocular rosacea were recruited. SD-OCT could detect abnormal changes in the POV in 100% of the lesion sites. In presumed-healthy areas of the diseased eyes diagnosed by slit-lamp biomicroscopy, SD-OCT detected abnormal changes in the POV in 100% of the eyes in both groups. In patients with unilateral disease, abnormal changes in the POV were detected by SD-OCT in 50% and 100% of presumed-healthy eyes diagnosed by slit-lamp biomicroscopy in the AWE group and phlyctenular keratitis/ocular rosacea group, respectively. SD-OCT is powerful in detecting POV changes in ocular surface disorders and can provide useful information that cannot be provided by slit-lamp biomicroscopy.

scholarly journals Design and Implementation Guidelines for a Modular Spectral-Domain Optical Coherence Tomography Scanner

2018 ◽  
Vol 2018 ◽  
pp. 1-22 ◽  
Author(s):  
Farid Atry ◽  
Israel Jacob De La Rosa ◽  
Kevin R. Rarick ◽  
Ramin Pashaie
Keyword(s):  
Optical Coherence Tomography ◽  
Imaging System ◽  
Optical Design ◽  
Spectral Domain ◽  
Design Parameters ◽  
Optical Coherence ◽  
Custom Made ◽  
Essential Knowledge ◽  
Sd Oct

In the past decades, spectral-domain optical coherence tomography (SD-OCT) has transformed into a widely popular imaging technology which is used in many research and clinical applications. Despite such fast growth in the field, the technology has not been readily accessible to many research laboratories either due to the cost or inflexibility of the commercially available systems or due to the lack of essential knowledge in the field of optics to develop custom-made scanners that suit specific applications. This paper aims to provide a detailed discussion on the design and development process of a typical SD-OCT scanner. The effects of multiple design parameters, for the main optical and optomechanical components, on the overall performance of the imaging system are analyzed and discussions are provided to serve as a guideline for the development of a custom SD-OCT system. While this article can be generalized for different applications, we will demonstrate the design of a SD-OCT system and representative results for in vivo brain imaging. We explain procedures to measure the axial and transversal resolutions and field of view of the system and to understand the discrepancies between the experimental and theoretical values. The specific aim of this piece is to facilitate the process of constructing custom-made SD-OCT scanners for research groups with minimum understanding of concepts in optical design and medical imaging.

scholarly journals External limiting membrane: retinal structural barrier in diabetic macular edema

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Sandeep Saxena ◽  
Levent Akduman ◽  
Carsten H. Meyer
Keyword(s):  
Optical Coherence Tomography ◽  
Macular Edema ◽  
Diabetic Macular Edema ◽  
Spectral Domain ◽  
Optical Coherence ◽  
Barrier Effect ◽  
External Limiting Membrane ◽  
Ellipsoid Zone ◽  
Structural Barrier ◽  
Sd Oct

AbstractAdvances in spectral-domain optical coherence tomography (SD-OCT) technology have enhanced the understanding of external limiting membrane (ELM) and ellipsoid zone (EZ) in diabetic macular edema. An increase in VEGF has been demonstrated to be associated with sequential ELM and EZ disruption on SD-OCT. An intact ELM is a prerequisite for an intact EZ in DME. Anti-VEGF therapy leads to restoration of barrier effect of ELM. The ELM restores first followed by EZ restoration.

Reliability of Corneal, Epithelial, and Stromal Thickness Mapping for a 9-mm Zone Using Spectral-Domain Optical Coherence Tomography

2021 ◽  
Author(s):  
Daniel Krause ◽  
Niklas Mohr ◽  
Mehdi Shajari ◽  
Wolfgang J. Mayer ◽  
Siegfried Priglinger ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Intraclass Correlation ◽  
Age Groups ◽  
Corneal Stroma ◽  
Correlation Coefficients ◽  
Spectral Domain ◽  
Optical Coherence ◽  
Noninvasive Technique ◽  
Intraclass Correlation Coefficients ◽  
Sd Oct

Abstract Purpose To evaluate the reliability of spectral-domain optical coherence tomography (SD-OCT; RTVue XR; Optovue, Inc., Fremont, CA, USA) for thickness mapping of the entire cornea (CT), corneal epithelium (ET). and corneal stroma (ST) over a 9-mm zone in healthy eyes. We sought to develop reference values for different age groups and elucidate potential sex- and age-dependent characteristics of corneal sublayer pachymetry maps. Methods Three consecutive SD-OCT scans were obtained in 166 healthy right eyes (mean age = 50 ± 20 years). The thickness maps contain 25 sectors over a 9-mm diameter zone. To test measurement reliability, intraclass correlation coefficients (ICC), coefficients of variation (CoV), and within-subject standard deviations (WSSD) were calculated. Results CT, ET, and ST ICCs ranged from 0.961 to 0.998, 0.896 to 0.945, and 0.955 to 0.998, respectively. CoV values for CT, ET, and ST ranged between 0.3 and 1.5%, 1.6 and 4.2%, and 0.4 and 1.7%, respectively. WSSD ranged from 6 to 41, 4 to 8, and 7 to 46 µm, respectively. A negative correlation was found between age and ET (p < 0.05) but not between age and ST or CT. No gender-related differences in CT, ET, or ST were detected. CoV of CT, ET, and ST measurements showed a positive correlation with age in 28, 64, and 28% of the sectors, respectively. Conclusion SD-OCT is a rapid and noninvasive technique that provides excellent reliability for corneal sublayer thickness measurements over a 9-mm zone. The reliability of the ET measurement seems to be negatively affected by age. Peripheral CT and global ET thin with age.

Compressive sensing for polarization sensitive optical coherence tomography

2021 ◽  
Author(s):  
Jianfeng Wang ◽  
Eric Chaney ◽  
Edita Aksamitiene ◽  
Marina Marjanovic ◽  
Stephen A Boppart
Keyword(s):  
Optical Coherence Tomography ◽  
Compressive Sensing ◽  
Optical Coherence

scholarly journals Spectral-Domain Optical Coherence Tomography-Based Morphofunctional Characterization of Dome-Shaped Maculopathy in Indian Population

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Naresh Babu Kannan ◽  
Sagnik Sen ◽  
Prithviraj Udaya ◽  
Obuli Ramachandran ◽  
Kim Ramasamy
Keyword(s):  
Optical Coherence Tomography ◽  
Indian Population ◽  
Subretinal Fluid ◽  
Cross Sectional Study ◽  
Spectral Domain ◽  
Dome Height ◽  
Optical Coherence ◽  
Cross Sectional ◽  
Sd Oct

Purpose. To study the clinicodemographic profile of dome-shaped maculopathy (DSM) eyes in the Indian population and characterization using spectral-domain optical coherence tomography (SD-OCT). Methods. This observational cross-sectional study included 25 eyes of 14 patients diagnosed with DSM. All eyes underwent SD-OCT for characterization of the dome profile and also to measure central macular thickness (CMT), subfoveal choroidal thickness (SFCT), and dome height (DH) and to detect the presence of subretinal fluid (SRF). Results. The mean age of patients was 48.36 ± 14.23 years (range, 28–65 years). Eleven patients had bilateral involvement. Mean axial length of all eyes was 24.25 ± 1.95 mm and mean spherical equivalent −4.23 ± 3.79 DS. Overall, 11/25 eyes (44%) had round domes, 9/25 eyes (36%) had horizontal domes, and 5/25 eyes (20%) had vertical domes, with a mean dome height at fovea of 500.54 ± 291.58 µm. Vertical domes had higher DH compared to horizontal or combined domes p = 0.02 . Six eyes (6/25, 24%) showed the presence of SRF; 60% of vertical domes had SRF, and 22.2% of horizontal domes had SRF. The eyes having SRF had significantly higher CMT p = 0.017 and DH p = 0.001 , especially in horizontal domes p = 0.023 . The eyes with thicker SFCT tended to have higher DH and poorer visual acuity. Conclusion. Indian DSM eyes may have relatively lesser amounts of myopia. Choroidal thickening may play a role in development of DSM and may also be related to development of subretinal fluid in such eyes.

Non-Distorted Imaging Depth of Optical Coherence Tomography System in Human Dental Tissues

2014 ◽  
Vol 34 (2) ◽  
pp. 0217001
Author(s):  
石博雅 Shi Boya ◽  
孟卓 Meng Zhuo ◽  
刘铁根 Liu Tiegen ◽  
王龙志 Wang Longzhi
Keyword(s):  
Optical Coherence Tomography ◽  
Optical Coherence ◽  
Optical Coherence Tomography System ◽  
Dental Tissues ◽  
Tomography System ◽  
Imaging Depth

scholarly journals Macular thickness measurements of healthy, naïve cynomolgus monkeys assessed with spectral-domain optical coherence tomography (SD-OCT)

PLoS ONE ◽  
2019 ◽  
Vol 14 (10) ◽  
pp. e0222850 ◽  
Author(s):  
Nora Denk ◽  
Peter Maloca ◽  
Guido Steiner ◽  
Christian Freichel ◽  
Simon Bassett ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Macular Thickness ◽  
Spectral Domain ◽  
Optical Coherence ◽  
Cynomolgus Monkeys ◽  
Thickness Measurements ◽  
Sd Oct

scholarly journals Early Detection of Incipient Retinal Pigment Epithelium Atrophy Overlying Drusen with Fundus Autofluorescence vs. Spectral Domain Optical Coherence Tomography

2020 ◽  
Vol 2020 ◽  
pp. 1-8 ◽  
Author(s):  
Anabel Rodríguez ◽  
Marc Biarnés ◽  
Rosa M. Coco-Martin ◽  
Anna Sala-Puigdollers ◽  
Jordi Monés
Keyword(s):  
Optical Coherence Tomography ◽  
Retinal Pigment Epithelium ◽  
Median Time ◽  
Pigment Epithelium ◽  
Fundus Autofluorescence ◽  
Retinal Pigment ◽  
Geographic Atrophy ◽  
Optical Coherence ◽  
Rpe Atrophy ◽  
Sd Oct

Purpose. This study aims to find out which tool, fundus autofluorescence (FAF) or spectral domain optical coherence tomography (SD-OCT), is more sensitive in detecting retinal pigment epithelium (RPE) demise overlying drusen and can, therefore, help predict geographic atrophy (GA) appearance in Age-Related Macular Degeneration (AMD). Methods. A single-site, retrospective, observational, longitudinal study was conducted. Patients with intermediate AMD (iAMD) (large (>125 μm) or intermediate (63–125 μm) drusen with hyper/hypopigmentation) with a minimum follow-up of 18 months were included. Drusen with overlying incipient RPE atrophy were identified on SD-OCT defined as choroidal hypertransmission or nascent geographic atrophy (nGA). These selected drusen were, then, traced backwards in time to determine if incipient RPE atrophy overlying drusen was observed on FAF (well-demarcated region of absence of autofluorescence) before, simultaneously, or after having detected the first signs of incipient RPE atrophy on SD-OCT. The number of drusen in which signs of incipient RPE atrophy was detected earlier using FAF or SD-OCT was compared. The time elapsed from the identification with the more sensitive method to the other was recorded and analyzed. Results. One hundred and thirty-three drusen in 22 eyes of 22 patients were included. Of these, 112 (84.2%) drusen showed choroidal hypertransmission and 21(15.8%) nGA. Early signs of atrophy overlying drusen were found simultaneously on SD-OCT and FAF in 52 cases (39.1%, 95% CI 30.8–47.9%), earliest on FAF in 51 (38.3%, 95% CI 30.0–47.2%) and first on SD-OCT in 30 (22.6%, 95% CI 15.8–30.6%; p<0.05). Statistically significant differences were found between both techniques (p=0.005), with FAF detecting it earlier than SD-OCT. When RPE atrophy was found first on FAF, the median time to diagnosis with SD-OCT was 6.6 months (95% CI 5.5 to 8.6), while if detection occurred earlier on SD-OCT, the median time until identification with FAF was 12.6 months (95% CI 6.0 to 23.4; p=0.0003). Conclusions. In iAMD cases in which early atrophy overlying drusen is not detected simultaneously in FAF and SD-OCT, FAF was significantly more sensitive. Nevertheless, a multimodal approach is recommended and required to evaluate these patients.

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