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

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.

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Contrast enhancement of optical coherence tomography images using least squares fitting and histogram matching

Optics Communications ◽

10.1016/j.optcom.2007.07.003 ◽

2007 ◽

Vol 279 (1) ◽

pp. 23-26 ◽

Cited By ~ 10

Author(s):

Yiheng Liu ◽

Yanmei Liang ◽

Zhengrong Tong ◽

Xiaonong Zhu ◽

Guoguang Mu

Keyword(s):

Optical Coherence Tomography ◽

Least Squares ◽

Contrast Enhancement ◽

Optical Coherence ◽

Least Squares Fitting ◽

Histogram Matching

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Investigation of Light Parameters on Image Quality and Optical Coherence Tomography

International Journal of Optics ◽

10.1155/2021/2322858 ◽

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.

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

OSA Continuum ◽

10.1364/osac.394157 ◽

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

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

Frontiers in Medicine ◽

10.3389/fmed.2021.696447 ◽

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 < 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 < 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.

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