Analysis of Imaging Performance of Optical Coherence Tomography Based on Differential Standard Deviation of Log-Scale Intensity

2018 ◽  
Vol 45 (4) ◽  
pp. 0407002
Author(s):  
张兰兰 Zhang Lanlan ◽  
高万荣 Gao Wanrong ◽  
史伟松 Shi Weisong
Keyword(s):  
Optical Coherence Tomography ◽  
Standard Deviation ◽  
Optical Coherence ◽  
Imaging Performance

scholarly journals Pterygia measurements are more accurate with anterior segment optical coherence tomography - A pilot study

1970 ◽  
Vol 3 (1) ◽  
pp. 9-12 ◽  
Author(s):  
MN Welch ◽  
CD Reilly ◽  
K Kalwerisky ◽  
A Johnson ◽  
SG Waller
Keyword(s):  
Optical Coherence Tomography ◽  
Standard Deviation ◽  
Pilot Study ◽  
Clinical Assessment ◽  
Anterior Segment ◽  
Optical Coherence ◽  
Slit Lamp ◽  
Significant Difference ◽  
The Mean ◽  
The Difference

Introduction: Slit-lamp beam measurements of a pterygium can be difficult to reproduce accurately. Purpose: To compare standard slit-lamp beam measurements of pterygia to computer caliper measurements of Anterior Segment Optical Coherence Tomography (OCT) images. Subjects and methods: Thirteen pterygia of ten patients were evaluated. Two physicians independently measured each pterygium using the slit lamp beam. Caliper measurements of two different OCT images of each pterygium were obtained. All measurements determined the distance from the limbus to the pterygium apex. Results: The difference in the slit lamp beam measurements of each pterygium was calculated and the mean of the differences was 0.3 and the standard deviation was 0.32. The difference in the two OCT measurements of each pterygium was also calculated and the mean of the differences was 0.1 and the standard deviation was 0.12. A two-tailed t-test demonstrated a statistically significant difference in these measurements (p = 0.0256). Conclusion: Anterior Segment Optical Coherence Tomography (OCT) gives significantly more reproducible results than the slit lamp beam for measurements of the distance of a pterygium’s apex from the limbus. This tool may provide more accurate clinical assessment of extension of pterygia onto the cornea and may be useful for research purposes. Key words: pterygium; pterygia; anterior segment optical coherence tomography; OCT DOI: 10.3126/nepjoph.v3i1.4271Nepal J Ophthalmol 2011;3(5):9-12

Optical coherence tomography angiography and arterial hypertension: A role in identifying subclinical microvascular damage?

2019 ◽  
pp. 112067211988039 ◽  
Author(s):  
Simone Donati ◽  
Andrea Maria Maresca ◽  
Jennifer Cattaneo ◽  
Alessandra Grossi ◽  
Marco Mazzola ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Standard Deviation ◽  
Arterial Hypertension ◽  
Healthy Subjects ◽  
Optical Coherence Tomography Angiography ◽  
Optical Coherence ◽  
Microvascular Damage ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

Introduction: To evaluate retinal microvasculature modifications by means of optical coherence tomography angiography in human subjects diagnosed with arterial hypertension and to assess potential clinical relevance for early diagnosis. Methods: A cross-sectional study of 30 subjects affected by arterial hypertension compared to a matched cohort of healthy patients was conducted. Patients were evaluated by the Outpatient Clinic for Hypertension and the Retina Center, University of Insubria, Varese, Italy. Patients were divided into three groups: Group 1—healthy subjects, Group 2—patients first diagnosed with hypertension, and Group 3—patients with treated hypertension. Optical coherence tomography angiography was performed applying different analysis protocols for macula and optic disk, using an AngioVue OCTA System on an Optovue device. Morphological data were compared to and correlated with clinical vascular parameters, to evaluate preclinical microvascular damage. Results: A significant reduction in deep vascular layer density (Group 1: 59.2% ± 1.5% standard deviation; Group 2: 59.2% ± 2.2% standard deviation; Group 3: 57.8% ± 2.6% standard deviation; p < 0.05) as well as an enlargement of the deep foveal avascular zone area (Group 1: 0.34 ± 0.09 mm2; Group 2: 0.36 ± 0.07 mm2; Group 3: 0.39 ± 0.1 mm2; p < 0.05) was measured in patients with first diagnosed hypertension and in treated patients compared to healthy subjects. We also observed a significant decrease in mean foveal choroidal thickness in affected patients compared to controls (Group 1: 319.68 ± 61.72 µm standard deviation; Group 2: 251.04 ± 63.1 µm standard deviation; Group 3: 262.65 ± 51.08 µm standard deviation; p < 0.05). Our preliminary data did not show a significant correlation with microalbuminuria levels. Discussion: Retinal vascular density showed pathological modifications between healthy subjects and hypertensive patients. These preliminary findings suggest that optical coherence tomography angiography may identify pathological markers of an early hypertensive damage and help monitor disease progression with potential therapeutic advantages.

scholarly journals Automatic intraoperative optical coherence tomography positioning

2020 ◽  
Vol 15 (5) ◽  
pp. 781-789 ◽  
Author(s):  
Matthias Grimm ◽  
Hessam Roodaki ◽  
Abouzar Eslami ◽  
Nassir Navab
Keyword(s):  
Optical Coherence Tomography ◽  
Standard Deviation ◽  
Ex Vivo ◽  
Anterior Segment ◽  
Semantic Segmentation ◽  
Recognition Algorithm ◽  
Optical Coherence ◽  
Cross Sectional ◽  
Intraoperative Optical Coherence Tomography ◽  
The Mean

Abstract Purpose Intraoperative optical coherence tomography (iOCT) was recently introduced as a new modality for ophthalmic surgeries. It provides real-time cross-sectional information at a very high resolution. However, properly positioning the scan location during surgery is cumbersome and time-consuming, as a surgeon needs both his hands for surgery. The goal of the present study is to present a method to automatically position an iOCT scan on an anatomy of interest in the context of anterior segment surgeries. Methods First, a voice recognition algorithm using a context-free grammar is used to obtain the desired pose from the surgeon. Then, the limbus circle is detected in the microscope image and the iOCT scan is placed accordingly in the X–Y plane. Next, an iOCT sweep in Z direction is conducted and the scan is placed to centre the topmost structure. Finally, the position is fine-tuned using semantic segmentation and a rule-based system. Results The logic to position the scan location on various anatomies was evaluated on ex vivo porcine eyes (10 eyes for corneal apex and 7 eyes for cornea, sclera and iris). The mean euclidean distances (± standard deviation) was 76.7 (± 59.2) pixels and 0.298 (± 0.229) mm. The mean execution time (± standard deviation) in seconds for the four anatomies was 15 (± 1.2). The scans have a size of 1024 by 1024 pixels. The method was implemented on a Carl Zeiss OPMI LUMERA 700 with RESCAN 700. Conclusion The present study introduces a method to fully automatically position an iOCT scanner. Providing the possibility of changing the OCT scan location via voice commands removes the burden of manual device manipulation from surgeons. This in turn allows them to keep their focus on the surgical task at hand and therefore increase the acceptance of iOCT in the operating room.

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 Potential Imaging Capability of Optical Coherence Tomography as Dental Optical Probe: A Mini-Review

2021 ◽  
Vol 11 (22) ◽  
pp. 11025
Author(s):  
Ramadhan Hardani Putra ◽  
Nobuhiro Yoda ◽  
Eha Renwi Astuti ◽  
Keiichi Sasaki
Keyword(s):  
Optical Coherence Tomography ◽  
Soft Tissues ◽  
Optical Probe ◽  
Periodontal Pocket ◽  
Optical Coherence ◽  
Imaging Capability ◽  
Online Searches ◽  
Imaging Performance ◽  
Clinical Experiments ◽  
Further Development

Optical coherence tomography (OCT) has been emerging in the dental field as an alternative diagnostic imaging for “optical probes” owing to its micro-meter resolution and non-invasiveness. This review aims to answer the following question: what is the imaging capability of OCT to visualize the subgingival area? Online searches were performed on PubMed and SPIE digital library databases, followed by a manual screening of references listed in relevant studies. The feasibility and imaging performance of OCT to visualize the subgingival area, including the periodontal, peri-implant, and crown margins, are discussed. All of the literature reviewed in this study demonstrated that OCT has the ability to visualize periodontal, including hard and soft tissues, and peri-implant conditions with high resolution. Gingival sulcus depth, periodontal pocket, and calculus deposition can also be depicted. However, clinical evidence that support the imaging capability of OCT as a dental optical probe to visualize subgingival area is lacking. Limited availability, portability, and usability of OCT for clinical experiments in dentistry, particularly for the subgingival area, might be contributed to its limitations. Hence, further development of handheld OCT systems and controlled clinical trials are needed to confirm the imaging capability of OCT reported in this review.

New visual field indices of disharmony for early diagnosis of glaucoma, alone or associated with conventional parameters

2018 ◽  
Vol 28 (5) ◽  
pp. 590-597
Author(s):  
Rodrigo Abreu-Gonzalez ◽  
Marta Gonzalez-Hernandez ◽  
Cristina Pena-Betancor ◽  
Paloma Rodriguez-Esteve ◽  
Manuel Gonzalez De La Rosa
Keyword(s):  
Optical Coherence Tomography ◽  
Standard Deviation ◽  
Visual Field ◽  
Early Diagnosis ◽  
Structural Data ◽  
Cross Sectional Study ◽  
University Hospital ◽  
Mean Deviation ◽  
Optical Coherence ◽  
Cross Sectional

Purpose: To evaluate the specificity of new perimetric indices based on harmony, alone and in combination with structural data, for glaucoma detection. Methods: In this prospective observational cross-sectional study, one eye of 105 healthy subjects and 97 early and suspect glaucomas were sequentially included and examined with Cirrus optical coherence tomography, twice with OCULUS Smartfield perimeter (SPARK strategy) and twice with Humphrey Analyzer (24-2 SITA-Fast) at the Ophthalmology Department from the University Hospital La Candelaria. Disharmony in the visual field was evaluated including vertical threshold symmetry, threshold rank), and homogeneity (threshold standard deviation from its maximum) using the patient himself/herself as a reference. We also evaluated disharmony in combination with the mean deviation and the pattern standard deviation in a single index (mismatch) and various combinations of morphological and functional indices. Combinations used a new score based on values above certain critical cut-off levels of each index. Results: For 95% specificity, the highest sensitivities were as follows: vertical cup/disc ratio: 28.9%; SPARK threshold rank: 29.9%; and SITA-Fast threshold standard deviation: 28.9%. For the combined indices and 100% specificity, they were 5 SPARK indices mismatch: 10.3%; 5 SITA-Fast indices mismatch: 11.3%; 8 optical coherence tomography indices: 21.9%; 13 SPARK and optical coherence tomography indices: 27.8%; and 13 SITA-Fast and optical coherence tomography indices: 32.0%. Conclusion: Disharmony combined with normative value-based indices and/or optical coherence tomography indices is useful for very specific early diagnosis of glaucoma.

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