Optical Coherence Tomography Angiography Evaluation of the Parafoveal Vasculature and Its Relationship With Ocular Factors

Tan, Colin S.; Lim, Louis W.; Chow, Vernon S.; Chay, Isaac W.; Tan, Seng C.; Cheong, Kai Xiong; Tan, Gabriel T.; Sadda, Srinivas R

doi:10.1167/iovs.15-18869

Cited by 144 publications

(143 citation statements)

References 41 publications

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“…Consistent with previous reports in normal eyes, we also found that an inverse association between FAZ area on the superficially capillary plexus and central subfield macular thickness, suggesting that a thinner foveal thickness is characterized by less compact and a larger degree of separation of the inner retinal layers over the foveolar center, and hence a larger FAZ 24,29,30 . We did not observe any statistically significant associations between OCT-A metrics and the presence of DME on the superficially capillary plexus.…”

Section: Discussionsupporting

confidence: 92%

“…Recent OCT-A studies have further found that enlarged FAZ is correlated with reduced VA 8,17,22 . Nevertheless, it is noted that size of FAZ varies among individuals and thus it is not easy to assess possible pathologic FAZ enlargement in the setting of retinal diseases 23,24 . Furthermore, AL had a significant influence on FAZ area measurement as shown in our study which is possibly due to ocular magnification, similar to other OCT measurements 25,26 .…”

Section: Discussionmentioning

confidence: 99%

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Determinants of Quantitative Optical Coherence Tomography Angiography Metrics in Patients with Diabetes

Tang

Lam

et al. 2017

Sci Rep

171

172

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Early microvascular damage in diabetes (e.g. capillary nonperfusion and ischemia) can now be assessed and quantified with optical coherence tomography-angiography (OCT-A). The morphology of vascular tissue is indeed affected by different factors; however, there is a paucity of data examining whether OCT-A metrics are influenced by ocular, systemic and demographic variables in subjects with diabetes. We conducted an observational cross-sectional study and included 434 eyes from 286 patients with diabetes. Foveal avascular zone (FAZ) area, FAZ circularity, total and parafoveal vessel density (VD), fractal dimension (FD), and vessel diameter index (VDI) from the superficial capillary plexus OCT-angiogram were measured by a customized automated image analysis program. We found that diabetic retinopathy (DR) severity was associated with increased FAZ area, decreased FAZ circularity, lower VD, lower FD, and increased VDI. Enlarged FAZ area was correlated with shorter axial length and thinner central subfield macular thickness. Decreased FAZ circularity was correlated with a reduction in visual function. Decreased VD was correlated with thinner macular ganglion-cell inner plexiform layer. Increased VDI was correlated with higher fasting glucose level. We concluded that the effects of ocular and systemic factors in diabetics should be taken into consideration when assessing microvascular alterations via OCT-A.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Determinants of Quantitative Optical Coherence Tomography Angiography Metrics in Patients with Diabetes

Tang

Lam

et al. 2017

Sci Rep

171

172

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“…The FAZ surface area in the SCP, as well as DCP, was significantly smaller in boys than in girls. These findings are consistent with previous studies on adults [7-9]. The study by Zhang et al [13], which examined Chinese children aged 8–16 years also showed a smaller FAZ surface area in boys in the SCP.…”

Section: Discussionsupporting

confidence: 93%

“…As a result, no recognised norms exist for paediatric OCTA parameters. Recently, in adults, differences have been shown between sexes in the foveal avascular zone (FAZ) surface area [7-9]. Similarly, no reference parameters exist for structural OCT in children, although the norms are likely to be different from adults due to the known differences in choroidal thickness with age [10-12].…”

Section: Introductionmentioning

confidence: 99%

Sex-Related Variations of Retinal and Choroidal Thickness and Foveal Avascular Zone in Healthy and Diabetic Children Assessed by Optical Coherence Tomography Imaging

et al. 2019

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Purpose of the Study: The aim of this study was to investigate the presence of gender differences in the chorioretinal microvasculature of children with and without vascular pathology. Methods: Healthy and type 1 diabetic children without diabetic retinopathy underwent optical coherence tomography angiography (OCTA) and structural OCT. We measured the foveal avascular zone (FAZ) area in the superficial capillary plexus (SCP) and deep CP (DCP), central retina, and choroid thickness. Results: OCTA examination was conducted in 112 diabetic and 30 healthy children, and structural OCT in 121 diabetic children and 32 controls. DCP FAZ area in boys was significantly smaller than in girls both in diabetics (p = 0.0010) and healthy children (p = 0.0302). In diabetics, SCP FAZ area was significantly smaller in boys (p = 0.0006), analogically to controls (p = 0.0870). Central retinal thickness was significantly greater in boys compared with girls in diabetics (p = 0.0001) and controls (p = 0.1008). Conclusion: Significant differences exist in the FAZ area and retinal thickness between sexes, likely representing physiological differences. Different norms must be used for boys and girls regardless of diabetic status.

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“…Across a number of studies, mean area of the superficial FAZ using OCT-A ranges from 0.24 to 0.30 mm 2 in healthy eyes. 11,14,15 However, as with other OCT-based measurements (such as retinal nerve fiber layer [RNFL] thickness, foveal morphology, and retinal thickness), it is critical to evaluate factors affecting the accuracy and reliability of FAZ measurements.…”

Section: Introductionmentioning

confidence: 99%

Assessing the Accuracy of Foveal Avascular Zone Measurements Using Optical Coherence Tomography Angiography: Segmentation and Scaling

Linderman

Salmon

Strampe

et al. 2017

Trans. Vis. Sci. Tech.

109

112

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PurposeThe foveal avascular zone (FAZ) is altered in numerous diseases. We assessed factors (axial length, segmentation method, age, sex) impacting FAZ measurements from optical coherence tomography (OCT) angiography images.MethodsWe recruited 116 Caucasian subjects without ocular disease, and acquired two 3 × 3 mm AngioVue scans per each right eye (232 total scans). In images of the superficial plexus, the FAZ was segmented using the AngioVue semiautomatic nonflow measurement tool and ImageJ manual segmentation. In images from the full retinal thickness, the FAZ was segmented using the AngioAnalytics automatic FAZ tool. Repeatability, reliability, and reproducibility were calculated for FAZ measurements (acircularity, area).ResultsFAZ area (mean ± SD) for manual segmentation was 0.257 ± 0.104 mm2, greater than both semiautomatic (0.231 ± 0.0939 mm2) and automatic (0.234 ± 0.0933 mm2) segmentation (P < 0.05). Not correcting for axial length introduced errors up to 31% in FAZ area. Manual area segmentation had better repeatability (0.022 mm2) than semiautomatic (0.046 mm2) or automatic (0.060 mm2). FAZ acircularity had better repeatability with automatic than manual segmentation (0.086 vs. 0.114). Reliability of all area measurements was excellent (intraclass correlation coefficient [ICC] = 0.994 manual, 0.969 semiautomatic, 0.948 automatic). Reliability of acircularity measurements was 0.879 for manual and 0.606 for automatic.ConclusionWe identified numerous factors affecting FAZ measurements. These errors confound comparisons across studies and studies examining factors that may correlate with FAZ measures.Translational RelevanceUsing FAZ measurements as biomarkers for disease progression requires assessing and controlling for different sources of error. Not correcting for ocular magnification can result in significant inaccuracy in FAZ measurements, while choice of segmentation method affects both repeatability and accuracy.

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Optical Coherence Tomography Angiography Evaluation of the Parafoveal Vasculature and Its Relationship With Ocular Factors

Abstract: The superficial and deep FAZ areas varied significantly among healthy eyes. Factors such as CRT, sex, SE, AL, and choroidal thickness influence the size of the FAZ.

Cited by 144 publications

References 41 publications

Determinants of Quantitative Optical Coherence Tomography Angiography Metrics in Patients with Diabetes

Determinants of Quantitative Optical Coherence Tomography Angiography Metrics in Patients with Diabetes

Sex-Related Variations of Retinal and Choroidal Thickness and Foveal Avascular Zone in Healthy and Diabetic Children Assessed by Optical Coherence Tomography Imaging

Assessing the Accuracy of Foveal Avascular Zone Measurements Using Optical Coherence Tomography Angiography: Segmentation and Scaling

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