In Vivo Assessment of Macular Vascular Density in Healthy Human Eyes Using Optical Coherence Tomography Angiography

PURPOSE. To investigate the macular quantitative parameters interchangeability of three different optical coherence tomography angiography (OCT-A) angiocubes (i.e., 3 3 3, 6 3 6, and 12 3 12 mm) on healthy subjects and patients affected by diabetic retinopathy (DR) and to assess the interrater reliability of such indices across the different scan protocols. METHODS.Retrospective study involving 20 eyes of healthy subjects and 20 eyes with DR. All eyes underwent swept-source OCT-A with 3 3 3-, 6 3 6-, and 12 3 12-mm angiocubes centered on the fovea. Foveal avascular zone (FAZ) area and vessel density on 3 3 3-, 6 3 6-, and 12 3 12-mm macular scans were calculated by three independent operators at all retina, superficial, deep, and choriocapillary vascular layers. Interchangeability and interrater reliabilities were estimated using intraclass correlation coefficient (ICC).RESULTS. Interscan reproducibility of FAZ area was very strong (ICC > 0.85) at every plexus. On the contrary, vessel density values significantly varied across different scan sizes (ICC < 0.51). Intrascan interrater reliability was high for all retina and superficial FAZ areas, while it was satisfactory at deep capillary plexus only for 3 3 3-mm scan.CONCLUSIONS. FAZ area at all plexuses is a robust parameter even if calculated on angiocubes with different size. However, interrater reliability is higher when measured in smaller scans. Conversely, vessel density results depend on the size of angiocube, although their interrater reliability is extremely high. Studies involving OCT-A should take into consideration that scan size may influence macular perfusion parameters and interrater reliability.

Section: Discussionmentioning

confidence: 99%

Macular Perfusion Parameters in Different Angiocube Sizes: Does The Size Matter in Quantitative Optical Coherence Tomography Angiography?

Rabiolo

Gelormini

Marchese

et al. 2018

“…This approach uses differences between B-scans to generate contrast associated with the motion of red blood cells (RBCs) through the microvasculature at various locations in the eye. 8,9 OCTA therefore enables detailed and reproducible images of the retinal microvasculature networks to be obtained with a high level of resolution. 10 The foveal avascular zone (FAZ) is the round, capillary-free zone within the macula.…”

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confidence: 99%

“…Measurements of FAZ size (area and perimeter) using OCTA have been shown to be highly reproducible in patients with microcirculatory deficiency involving the macula, such as diabetic retinopathy, as well as in healthy individuals. 9,11 Using OCTA images of the superficial vascular network, our group has previously reported an enlarged FAZ area in the perifoveal region, which was spatially correlated with central visual field (CVF) loss in glaucoma patients. 12 Furthermore, our subsequent study demonstrated that the FAZ area and perimeter showed significant diagnostic value in discriminating glaucomatous eyes with CVF defects from normal eyes.…”

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confidence: 99%

An Optical Coherence Tomography Angiography Study of the Relationship Between Foveal Avascular Zone Size and Retinal Vessel Density

Kwon

Choi²,

Shin

et al. 2018

PURPOSE. To assess the relationship between the size of the foveal avascular zone (FAZ; area and perimeter) and vessel density (VD) at various retinal regions using optical coherence tomography angiography (OCTA) in patients with open-angle glaucoma (OAG).METHODS. In this retrospective cross-sectional study, OAG eyes were grouped according to the presence/absence of central visual field (CVF) defects. A control group of normal eyes was also included. OCTA images were obtained from the optic nerve (4.5 3 4.5 mm 2 ) and macular (3 3 3 mm 2 ) area, in which VDs were measured in the circumpapilla, parafovea, and fovea regions. Partial correlation analyses between FAZ parameters representing size and VDs at different retinal regions were performed. The correlation between FAZ parameters and macular ganglion cell-inner plexiform layer thickness (mGCIPLT) and CVF mean sensitivity (MS) was also assessed. For spatial correspondence, correlations between FAZ parameters and corresponding VD, mGCIPLT, and CVF-MS measurements were assessed at each hemiretina. RESULTS.A total of 126 OAG eyes and 40 controls were reviewed. Overall, FAZ parameters showed statistically significant correlations with VDs measured at the fovea, parafovea, and circumpapilla (FAZ area: r ¼ À0.603, À0.385, À0.256; P < 0.001, < 0.001, and 0.003, respectively). These correlations were observed regardless of the presence of CVF defects (all P < 0.05). FAZ size showed significant spatial correlations with VD, mGCIPLT, and CVF-MS measurements at each hemiretina.CONCLUSIONS. OCTA-derived FAZ area and perimeter showed statistically significant correlations with VDs measured at various retinal locations with spatial correspondence in OAG.

“…Since macular capillaries are the primary site of injury in radiation maculopathy, OCTA is a powerful tool to investigate these pathologic changes. Moreover, the recent adjunction of quantitative tools to OCTA provides access to retinal microcirculatory metrics, such as foveal avascular zone (FAZ) dimensions, 5,6 capillary density, 7,8 and capillary network fractal dimension, 9 at the level of both plexuses. Fractal dimension is a promising endpoint to measure vascular network disorganization in OCTA images, which has been used successfully in diabetic retinopathy [10][11][12] and posterior uveitis.…”

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confidence: 99%

Radiation Maculopathy After Proton Beam Therapy for Uveal Melanoma: Optical Coherence Tomography Angiography Alterations Influencing Visual Acuity

Matet

Daruich

Zografos

2017

PURPOSE. To analyze microvascular and structural changes in radiation maculopathy and their influence on visual acuity (VA), using optical coherence tomography (OCT) and OCT angiography (OCTA).METHODS. This was a retrospective analysis of consecutive patients with radiation maculopathy, 12 months or more after proton-beam irradiation for uveal melanoma, imaged with fluorescein angiography, OCT, and OCTA. Clinical parameters potentially affecting VA were recorded, including OCTA-derived metrics: foveal avascular zone (FAZ) area, vascular density, and local fractal dimension of the superficial (SCP) and deep capillary plexuses (DCP). Nonirradiated fellow eyes served as controls. RESULTS.Ninety-three patients were included. FAZ was larger, while SCP/DCP capillary density and local fractal dimension were lower in the 35 irradiated than in the 35 fellow eyes (P < 0.0001). Microvascular alterations graded on fluorescein angiography (minimally damaged/ disrupted/disorganized) were correlated to FAZ area and SCP/DCP density on OCTA (P < 0.01). By univariate analysis, worse VA was associated to macular detachment at presentation (P ¼ 0.024), total macular irradiation (P ¼ 0.0008), higher central macular thickness (CMT) (P ¼ 0.019), higher absolute CMT variation (P < 0.0001), cystoid edema (P ¼ 0.030), ellipsoid zone disruption (P ¼ 0.002), larger FAZ (P < 0.0001), lower SCP (P ¼ 0.001) and DCP capillary density (P < 0.0001), and lower SCP (P ¼ 0.009) and DCP local fractal dimension (P < 0.0001). Two multivariate models with either capillary density or fractal dimension as covariate showed that younger age (P ¼ 0.014/0.017), ellipsoid zone disruption (P ¼ 0.034/0.019), larger FAZ (P ¼ 0.0006/0.002), and lower DCP density (P ¼ 0.008) or DCP fractal dimension (P ¼ 0.012), respectively, were associated with worse VA.CONCLUSIONS. VA of eyes with radiation maculopathy is influenced by structural and microvascular factors identified with OCTA, including FAZ area and DCP integrity.