scholarly journals Optical coherence tomography with balanced signal strength across the depth for pearl inspection

OSA Continuum ◽  
2020 ◽  
Vol 3 (7) ◽  
pp. 1739
Author(s):  
Huade Mao ◽  
Pingping Feng ◽  
Yu-Xuan Ren ◽  
Jiqiang Kang ◽  
Kevin K. Tsia ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Signal Strength ◽  
Optical Coherence

Relationship between Retinal Nerve Fiber Layer Measurement and Signal Strength in Optical Coherence Tomography

Ophthalmology ◽  
2008 ◽  
Vol 115 (8) ◽  
pp. 1347-1351.e2 ◽  
Author(s):  
Carol Yim Lui Cheung ◽  
Christopher Kai Shun Leung ◽  
Dusheung Lin ◽  
Chi-Pui Pang ◽  
Dennis Shun Chiu Lam
Keyword(s):  
Optical Coherence Tomography ◽  
Nerve Fiber ◽  
Retinal Nerve Fiber Layer ◽  
Signal Strength ◽  
Optical Coherence ◽  
Fiber Layer ◽  
Nerve Fiber Layer ◽  
Retinal Nerve Fiber

Repeatability of vessel density measurements of optical coherence tomography angiography in normal and glaucoma eyes

2017 ◽  
Vol 102 (3) ◽  
pp. 352-357 ◽  
Author(s):  
Jayasree P Venugopal ◽  
Harsha L Rao ◽  
Robert N Weinreb ◽  
Zia S Pradhan ◽  
Srilakshmi Dasari ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Repeated Measures ◽  
Optical Coherence Tomography Angiography ◽  
Signal Strength ◽  
Cross Sectional Study ◽  
Vessel Density ◽  
Optical Coherence ◽  
Cross Sectional ◽  
Density Measurements ◽  
Density Values

AimsTo compare the intrasession repeatability of peripapillary and macular vessel density measurements of optical coherence tomography angiography (OCTA) in normal and glaucoma eyes, and to evaluate the effect of signal strength of OCTA scans on the repeatability.MethodsIn a cross-sectional study, three optic nerve head scans each of 65 eyes (30 normal, 35 glaucoma eyes) and three macular scans each of 69 eyes (35 normal, 34 glaucoma eyes) acquired in the same session with OCTA were analysed. Repeatability was assessed using within-subject coefficient of repeatability (CRw) and variation (CVw). Effect of signal strength index (SSI) on repeatability was evaluated with repeated-measures mixed-effects models.ResultsCRw (%) and CVw (%) of peripapillary measurements in normal eyes ranged between 3.3 and 7.0, and 2.5 and 4.4 respectively, and that in glaucoma eyes between 3.5 and 7.1, and 2.6 and 6.6. For the macular, these measurements ranged between 4.1 and 6.0, and 3.3 and 4.7 in normal eyes and 4.3 and 6.9, and 3.7 and 5.6 in glaucoma eyes. Repeatability estimates of most measurements were similar in normal and glaucoma eyes. Vessel densities of both peripapillary and macular regions significantly increased with increase in SSI of repeat scans (coefficients ranging from 0.15 to 0.38, p<0.01 for all associations).ConclusionsRepeatability estimates of OCTA measured peripapillary and macular vessel densities were similar in normal eyes and eyes with glaucoma. SSI values of the scans had a significant effect on the repeatability of OCTA with the vessel density values increasing in scans with higher SSI values.

scholarly journals Investigation of Light Parameters on Image Quality and Optical Coherence Tomography

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Boka Fikadu ◽  
Bulcha Bekele ◽  
Leta Tesfaye Jule ◽  
Anatol Degefa ◽  
N. Nagaprasad ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Image Quality ◽  
Time Domain ◽  
Glass Sample ◽  
Michelson Interferometer ◽  
Signal Strength ◽  
Optical Coherence ◽  
Time Domain Signal ◽  
Significant Difference ◽  
The Time Domain

In this work, image quality and optical coherence tomography were studied. The results of the study show that there is a very significant difference between ultrasound and optical coherence tomography to produce an image with a different wave. To understand this, we studied the basic principle of optical coherence tomography in the Michelson interferometer using monochromatic and broadband sources. Time-domain and spectral-domain measurements, which exist at the detector level, are briefly described using a glass sample. The time-domain signal strength of the Michelson interferometer using a broadband source is a Gaussian envelope.

scholarly journals Macular Structure and Microvasculature Changes in AIDS-Related Cytomegalovirus Retinitis Using Optical Coherence Tomography Angiography

2021 ◽  
Vol 8 ◽  
Author(s):  
Kui-Fang Du ◽  
Xiao-Jie Huang ◽  
Chao Chen ◽  
Wen-Jun Kong ◽  
Lian-Yong Xie ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Choroidal Thickness ◽  
Optical Coherence Tomography Angiography ◽  
Retinal Thickness ◽  
Signal Strength ◽  
Cytomegalovirus Retinitis ◽  
Foveal Avascular Zone ◽  
Control Group ◽  
Optical Coherence ◽  
Avascular Zone

Background: Cytomegalovirus retinitis (CMVR) is a crucial blind-causing disease of AIDS-related ocular opportunistic infection. The CMVR lesions produced retinal necrosis. It is not entirely clear whether CMVR eyes without macular-involved necrotic lesions may have subtle macular damage. In this study, we conducted a cross-sectional study using optical coherence tomography angiography (OCTA) to evaluate macular microvasculature and structure in eyes with AIDS-related CMVR.Methods: Acquired immune deficiency syndrome (AIDS)-related CMVR patients (active and inactive CMVR) and healthy controls treated in the Department of Ophthalmology, Beijing Youan Hospital, Capital Medical University between August 25, 2019, and October 18, 2019, were recruited. All OCTA parameters, including the foveal avascular zone (FAZ), retinal vessel density (VD), choroidal vascularity index (CVI), retinal thickness, and choroidal thickness, were compared between groups after the signal strength was corrected.Results: Signal strength in the 3 × 3 and 6 × 6 mm scan patterns was significantly weaker in the inactive CMVR group than in the control group (both p &lt; 0.001). After adjusting for signal strength, heterogeneity in the central fovea and parafoveal quadrants was present with a shift toward lower macular chorioretinal vasculature, decreased full choroidal thickness, and thicker retinal thickness in the active and inactive CMVR groups. The retinal nerve fiber layer (RNFL) and inner nuclear layer (INL) were significantly thicker in the active and inactive CMVR groups than in the control group (all p &lt; 0.05). For photoreceptor-retinal pigment epithelium (PR-RPE) thickness, no significant differences were found in any quadrant between groups. Foveal avascular zone areas were not significantly different among the three groups (p = 0.053).Conclusions: Subtle macular structure and microvasculature damage still existed in CMVR eyes without macular-involved necrotic lesions. The results of our study are helpful for a deep understanding of the damage caused by CMVR.

scholarly journals Histogram Matching Extends Acceptable Signal Strength Range on Optical Coherence Tomography Images

2015 ◽  
Vol 56 (6) ◽  
pp. 3810 ◽  
Author(s):  
Chieh-Li Chen ◽  
Hiroshi Ishikawa ◽  
Gadi Wollstein ◽  
Richard A. Bilonick ◽  
Ian A. Sigal ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Signal Strength ◽  
Optical Coherence ◽  
Histogram Matching

Effect of algorithms and covariates in glaucoma diagnosis with optical coherence tomography angiography

2021 ◽  
pp. bjophthalmol-2020-318677
Author(s):  
Qi Sheng You ◽  
Ou Tan ◽  
Shaohua Pi ◽  
Liang Liu ◽  
Ping Wei ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Diagnostic Accuracy ◽  
Nerve Fibre ◽  
Optical Coherence Tomography Angiography ◽  
Signal Strength ◽  
Vessel Density ◽  
Optical Coherence ◽  
Glaucoma Diagnosis ◽  
Nerve Fibre Layer ◽  
Normal Controls

PurposeTo assess the effects of algorithms and covariates in glaucoma diagnosis with optical coherence tomography angiography (OCTA).MethodsIn this prospective cross-sectional study, one eye each of 36 normal controls and 64 patients with glaucoma underwent 4.5 mm disc-centred and 6 mm macula-centred OCTA scans. The peripapillary nerve fibre layer plexus capillary density (NFLP-CD) and macular superficial vascular complex vessel density (SVC-VD) were measured using both a commercial algorithm (AngioAnalytics) and a custom algorithm (Center for Ophthalmic Optics & Lasers Angiography Reading Toolkit (COOL-ART)). The nerve fibre layer and ganglion cell complex thicknesses were measured on structural OCT.ResultsThe overall peripapillary NFLP-CD and macular SVC-VD measured with the two algorithms were highly correlated but poorly agreed. Among the normal controls, the perfusion measurements made by both algorithms were significantly correlated with age. AngioAnalytics measurements were also correlated with signal strength index, while COOL-ART measurements were not. These covariates were adjusted. The diagnostic accuracy, measured as the area under the receiver operating characteristic curve for glaucoma detection, was not significantly different between algorithms, between structural and perfusion parameters and between the peripapillary and macular regions (All p>0.05). The macular SVC-VD in the 6 mm square had a significantly higher diagnostic accuracy than that of the central 3 mm square area (p=0.005).ConclusionsAngioAnalytics and COOL-ART vessel density measurements are not interchangeable but potentially interconvertible. Age and signal strength are significant covariates that need to be considered. Both algorithms and both peripapillary and macular perfusion parameters have similarly good diagnostic accuracy comparable to structural OCT. A larger macular analytic area provides higher diagnostic accuracy.

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