scholarly journals Five-Frame Variable Phase-Shifting Method for Full-Range Spectral-Domain Optical Coherence Tomography

2018 ◽  
Vol 8 (9) ◽  
pp. 1580
Author(s):  
Jiewen Lin ◽  
Shuncong Zhong ◽  
Qiukun Zhang ◽  
Weiqiang Chen
Keyword(s):  
Optical Coherence Tomography ◽  
Full Range ◽  
Anterior Segment ◽  
Phase Shifts ◽  
Phase Shifting ◽  
Spectral Domain ◽  
Complex Conjugate ◽  
Optical Coherence ◽  
Variable Phase ◽  
Sd Oct

In order to achieve a better complex conjugate artifacts (CCA) suppression, we propose a five-frame variable phase-shifting (FVP) method for spectral domain optical coherence tomography (SD-OCT). The traditional five-frame invariant phase-shifting (FIP) method employs five phase shifts correlate with the center wavelength. However, due to the effects of polychromatic errors, the FIP method cannot get excellent CCA suppression. In the present work, we employ FVP method using variable phase shifts which is dependent on all the wavelengths and therefore, theoretically, the system would have no effects of polychromatic errors. This is the reason why the FVP method would achieve better CCA suppression than the FIP method. Comparative studies between FIP and FVP methods are investigated in the work. Subsequently, we develop a homemade SD-OCT system involving a homemade spectrometer, by which the anterior segment of a rat’s eyeball is measured. The experimental results demonstrate that the quality of OCT images is significantly improved by using FVP method with an increase by a factor of 1.7 on the CCA suppression of SD-OCT. FVP provides a new strategy for complex conjugate artifacts suppression for spectral domain optical coherence tomography.

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.

scholarly journals Parabolic BM-scan technique for full range Doppler spectral domain optical coherence tomography

2010 ◽  
Vol 18 (2) ◽  
pp. 1358 ◽  
Author(s):  
Franck Jaillon ◽  
Shuichi Makita ◽  
Masaki Yabusaki ◽  
Yoshiaki Yasuno
Keyword(s):  
Optical Coherence Tomography ◽  
Full Range ◽  
Spectral Domain ◽  
Optical Coherence
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