Reproducibility and repeatability of foveal avascular zone measurements in healthy subjects by optical coherence tomography angiography

Macular Ischemia Changes in Patients with Diabetic Macular Edema Treated with Aflibercept and Ranibizumab

Τhis study aims to assess changes in the fovea avascular zone (FAZ) in treatment naïve patients receiving aflibercept or ranibizumab injections for diabetic macular edema (DME). Best corrected visual acuity (BCVA) testing, OCT, and OCT-angiography imaging were performed at baseline and 1 month after each injection. Injections of either aflibercept or ranibizumab were administered monthly for 6 consecutive months. FAZ in the superficial (SCP) and the deep capillary plexus (DCP) using OCT angiography was recorded for each visit. Fifty eyes from fifty patients with a mean age of 67.0 ± 10.7 years were included in the study. Twenty-five patients received aflibercept and twenty-five received ranibizumab. BCVA was 40.8 ± 10.0 and increased to 52.1 ± 7.9 ETDRS letters at the last visit (p < 0.001). CRT was 295.6 ± 34.0 at baseline and 247.9 ± 29.7 at the last study visit (p < 0.001). SCP FAZ was 350.6 ± 79.5 μm2 at baseline and 339.0 ± 71.3 μm2 after sox monthly injections (p = 0.132). DCP FAZ was 558.6 ± 199.0 μm2 at baseline and 459.5 ± 156.1 μm2 after six monthly injections (p < 0.001). There was no effect of the choice of ranibizumab or aflibercept on DCP FAZ change (p = 0.277). In conclusion, treatment with 6 monthly injections of ranibizumab and aflibercept led to an increase in BCVA and a decrease in CRT and DCP FAZ area. Both drugs led to an improvement in DCP ischemia.

CHANGES IN OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY MEASURES THROUGHOUT THE DAY: Diurnal Variation or Test-Retest Variability?

PURPOSE

To evaluate the repeatability and diurnal variation of the retinal vessel density and foveal avascular zone parameters using optical coherence tomography angiography.

METHODS

Forty-one healthy individuals were measured twice in the morning and once in the evening. Foveal avascular zone area, perimetry, foveal density; superficial and deep capillary plexus (superficial capillary plexus, deep capillary plexus) vessel density, and central macular thickness were evaluated with the intraclass correlation coefficient, coefficient of repeatability, and Bland-Altman plots.

RESULTS

Repeatability was evaluated with two consecutive scans taken in the morning. The coefficient of repeatabilities (%) was 5.4; 4.3, and 8.8 for the foveal avascular zone area, perimetry, and foveal density, respectively, with excellent intraclass correlation coefficients. Intraclass correlation coefficient was poor for parafovea (0.33), whereas excellent for fovea (0.97) in superficial capillary plexus-vessel density. Coefficient of repeatability for fovea and parafovea was 19.19% and 10.43%, respectively. Intraclass correlation coefficient values were poor (0.3-0.4) with 10% to 16% measurement differences in deep capillary plexus-vessel density parameters. Coefficient of repeatabilities for central macular thickness was between 1% and 2% with excellent intraclass correlation coefficient. The analysis on diurnal variation yielded comparable results.

CONCLUSION

Except for the parafoveal vessel density, optical coherence tomography angiography is a highly reproducible device for measuring foveal avascular zone and vessel density using 6 × 6 scans with undilated pupils. However, variation in optical coherence tomography angiography parameters observed throughout the day could be attributed to test-retest variation rather than diurnal rhythm.

Central and Peripheral Changes in Retinal Vein Occlusion and Fellow Eyes in Ultra-Widefield Optical Coherence Tomography Angiography

Purpose

To explore the central and peripheral retinal and choroidal changes in retinal vein occlusion (RVO) and fellow eyes using ultra-widefield swept-source optical coherence tomography angiography (UWF-SS-OCTA).

Methods

Fifteen ischemic central RVO (CRVO), 15 branch RVO (BRVO), and 15 age-matched healthy controls were prospectively recruited. Retinal and choroidal parameters, including retinal vessel flow density (VFD) and vessel linear density (VLD), choroidal vascularity volume (CVV), choroidal vascularity index (CVI), and VFD in the large and medium choroidal vessels (LMCV-VFD), were measured in the central and peripheral regions of the 24 × 20-mm UWF-SS-OCTA images.

Results

Ischemic CRVO and BRVO eyes showed increased foveal avascular zone area, perimeter, and acircularity index (AI) compared to their fellow eyes and healthy control eyes, and RVO fellow eyes also had larger AI values than controls (P < 0.05). For ischemic CRVO and BRVO eyes versus control eyes, VFD, VLD, CVV, CVI, and LMCV-VFD decreased, but retinal thickness and volume in the superficial capillary plexus, deep capillary plexus, and whole retina increased (P < 0.05). Moreover, RVO fellow eyes also showed significantly decreased retinal VFD, LMCV-VFD, and CVI, as well as increased retinal thickness and volume, compared with control eyes (P < 0.05). Alterations were not consistent throughout the retina, as they involved only the peripheral or central regions in some cases.

Conclusions

The affected and unaffected fellow eyes of RVO patients both demonstrated central and/or peripheral structural and vascular alterations in the retina and choroid. Because UWF-SS-OCTA enables visualization and evaluation of the vasculature outside the posterior pole, it presents a promising approach to more fully characterize vascular alterations in RVO.

OCT angiography and its retinal biomarkers [Invited]

Optical coherence tomography angiography (OCTA) is a high-resolution, depth-resolved imaging modality with important applications in ophthalmic practice. An extension of structural OCT, OCTA enables non-invasive, high-contrast imaging of retinal and choroidal vasculature that are amenable to quantification. As such, OCTA offers the capability to identify and characterize biomarkers important for clinical practice and therapeutic research. Here, we review new methods for analyzing biomarkers and discuss new insights provided by OCTA.

RHOMBUS DEFORMATION OF RETINAL LATERAL DISPLACEMENT AFTER EPIRETINAL MEMBRANE REMOVAL REVEALED BY DIFFEOMORPHIC IMAGE REGISTRATION

PURPOSE

To establish an analysis method using diffeomorphic image registration and evaluate microvascular displacement through epiretinal membrane (ERM) removal.

METHODS

Medical records of eyes that underwent vitreous surgery for ERM were reviewed. Postoperative optical coherence tomography angiography (OCTA) images were converted to the corresponding preoperative images according to a configured algorithm using diffeomorphism.

RESULTS

Thirty-seven eyes with ERM were examined. Measured changes in the foveal avascular zone (FAZ) area showed a significant negative correlation with central foveal thickness (CFT). The average amplitude of microvascular displacement calculated for each pixel was 69 ± 27 µ m in the nasal area, which was relatively smaller than that in other areas. The vector map, which included both the amplitude and the vector of microvasculature displacement, showed a unique vector flow pattern called the rhombus deformation sign in 17 eyes. Eyes with this deformation sign showed less surgery-induced changes in the FAZ area and CFT and a milder ERM stage than those without this sign.

CONCLUSION

The authors calculated and visualized microvascular displacement using diffeomorphism. The authors found a unique pattern (rhombus deformation) of retinal lateral displacement through ERM removal, which was significantly associated with the severity of ERM.

A Reliable Criterion for the Correct Delimitation of the Foveal Avascular Zone in Diabetic Patients

BACKGROUND

Manual segmentation of the Foveal Avascular Zone (FAZ) has a high level of variability. Research into retinas needs coherent segmentation sets with low variability.

METHODS

Retinal optical coherence tomography angiography (OCTA) images from type-1 diabetes mellitus (DM1), type-2 diabetes mellitus (DM2) and healthy patients were included. Superficial (SCP) and deep (DCP) capillary plexus FAZs were manually segmented by different observers. After comparing the results, a new criterion was established to reduce variability in the segmentations. The FAZ area and acircularity were also studied.

RESULTS

The new segmentation criterion produces smaller areas (closer to the real FAZ) with lower variability than the different criteria of the explorers in both plexuses for the three groups. This was particularly noticeable for the DM2 group with damaged retinas. The acircularity values were also slightly reduced with the final criterion in all groups. The FAZ areas with lower values showed slightly higher acircularity values. We also have a consistent and coherent set of segmentations with which to continue our research.

CONCLUSIONS

Manual segmentations of FAZ are generally carried out with little attention to the consistency of the measurements. A novel criterion for segmenting the FAZ allows segmentations made by different observers to be more similar.

Evaluation of retinal microvasculature in exotropia with abnormal binocular vision by optical coherence tomography angiography

BACKGROUND

To explore the retinal microvasculature in large-angle concomitant exotropia patients with abnormal binocular vision using optical coherence tomography angiography (OCTA) analysis.

METHODS

OCTA images of 52 healthy and 100 strabismic eyes were analyzed to quantify the retinal thickness (RT), superficial capillary plexus (SCP), deep capillary plexus (DCP), and foveal avascular zone (FAZ). Paired t-tests were performed to compare differences between the two groups, the dominant eye and the deviated eye in the exotropia group, respectively. A p-value < 0.01 was considered significant.

RESULTS

The mean angle of deviation was 79.38 [± 25.64] (prism diopters, PD). There were significant differences in the DCP in deviated eyes between the exotropia group and the control group (fovea: p = 0.007; temporal: p = 0.014; nasal: p = 0.028; inferior: p = 0.013). The temporal SCP in the exotropia group was significantly higher than in the control group in deviated eyes (p = 0.020). No significant difference was found between dominant eyes and strabismic eyes (p > 0.01).

CONCLUSIONS

The study showed that OCTA revealed subnormal DCP in patients with large-angle exotropia and abnormal binocularity which may be related to retinal suppression. Changes in the macular microvasculature may provide valuable insights into the development of strabismus. Further studies are needed to determine the clinical relevance of this finding.

TRIAL REGISTRATION

This trial is registered as ChiCTR2100052577 at www.Chictr.org.cn .

Macular Vascularity and Ganglion Cell Complex Parameters in the Young Adults with Myopia and Progressive Myopia

Purpose

The purpose of this study is to determine the relationships between foveal avascular zone (FAZ), foveal vascular density (FD) and GCC (ganglion cell complex) parameters in a healthy myopic population using optical coherence tomography angiography (angio-OCT).

Patients and Methods

Three hundred and eighty-one eyes of 381 healthy participants were included into this study and assigned to three groups according to their spherical equivalent (SE) values and an additional progressive myopia group. One randomly chosen eye from each patient was analyzed. GCC mean thickness, focal loss of volume (FLV), global loss of volume (GLV), FAZ area, FAZ perimeter, and FD parameters were obtained with the RTVue AngioOCT device.

Results

FAZ area and its perimeter were strongly correlated with the belonging spherical equivalent group (p = 0.0001, p = 0.0008 accordingly), being the largest in progressive myopia subgroup (mean size 0.42mm²). Other factors that were significantly higher in myopic eyes were FLV (p = 0.0023), GLV (p = 0.0020). There were no differences in FD between groups. In the myopic and progressive myopia groups, there was a significant relationship between FAZ area and FLV, GLV, and GCC thickness. We found that in myopic eyes with AXL exceeding 26.6 mm, FAZ becomes negatively correlated to mean GCC thickness.

Conclusion

In myopia, compared to non-myopic groups, there is a greater loss of neural tissue represented by a thinner GCC layer, greater FLV and GLV parameters, and worse blood supply represented by a larger FAZ area. Eye axial length of 26.6 mm is a breaking point, where the negative FAZ area to GCC thickness relationship curve is getting significantly steeper.

Foveal avascular zone in normal human eyes by optical coherence tomography angiography

OBJECTIVE

To analyze the influence factors of the area of superficial plexus foveal avascular zone (FAZ) and related indexes of fovea measured with optical coherence tomography angiography (OCT-A) in normal subjects.

METHODS

This was a cross-sectional study from November 2020 to May 2021 in the Inner Mongolia Autonomous Region, China. Each subject received related eye examination. The correlation between all the factors and superficial plexus FAZ were analyzed under univariable and multivariable linear regression analysis.

RESULTS

Finally, 239 subjects with sufficient data were recruited in the study, including 108 males and 131 females, aged 27.41±4.63 years. The area of superficial plexus FAZ was 0.33±0.16 mm². In the univariate regression, gender (β = 41.702, 95%CI: 9.152 to 74.253, P = 0.012), drinking (β = -66.074, 95%CI: -99.197 to -32.951, P = 0.001) and axial length (β = -15.874, 95%CI: -29.562 to -2.185, P = 0.023) were associated with superficial plexus FAZ area. In multivariate regression analysis results, drinking (β = -42.410, 95%CI = -79.388 to -5.432, P = 0.025) was significantly correlated with superficial plexus FAZ area.

CONCLUSION

The area of superficial plexus FAZ was not affected by age, gender, systematical and biochemical indicators, but related to the status of drinking.

Methods to measure blood flow and vascular reactivity in the retina

Disturbances of retinal perfusion are involved in the onset and maintenance of several ocular diseases, including diabetic retinopathy, glaucoma, and retinal vascular occlusion. Hence, knowledge on ocular vascular anatomy and function is highly relevant for basic research studies and for clinical judgment and treatment. The retinal vasculature is composed of the superficial, intermediate, and deep vascular layer. Detection of changes in blood flow and vascular diameter especially in smaller vessels is essential to understand and to analyze vascular diseases. Several methods to evaluate blood flow regulation in the retina have been described so far, but no gold standard has been established. For highly reliable assessment of retinal blood flow, exact determination of vessel diameter is necessary. Several measurement methods have already been reported in humans. But for further analysis of retinal vascular diseases, studies in laboratory animals, including genetically modified mice, are important. As for mice, the small vessel size is challenging requiring devices with high optic resolution. In this review, we recapitulate different methods for retinal blood flow and vessel diameter measurement. Moreover, studies in humans and in experimental animals are described.

A Deep Learning System Using Optical Coherence Tomography Angiography to Detect Glaucoma and Anterior Ischemic Optic Neuropathy

INTRODUCTION

Glaucoma and non-arteritic anterior ischemic optic neuropathy (NAION) are optic neuropathies that can both lead to irreversible blindness. Several studies have compared optical coherence tomography angiography (OCTA) findings in glaucoma and NAION in the presence of similar functional and structural damages with contradictory results. The goal of this study was to use a deep learning system to differentiate OCTA in glaucoma and NAION.

MATERIAL AND METHODS

Sixty eyes with glaucoma (including primary open angle glaucoma, angle-closure glaucoma, normal tension glaucoma, pigmentary glaucoma, pseudoexfoliative glaucoma and juvenile glaucoma), thirty eyes with atrophic NAION and forty control eyes (NC) were included. All patients underwent OCTA imaging and automatic segmentation was used to analyze the macular superficial capillary plexus (SCP) and the radial peripapillary capillary (RPC) plexus. We used the classic convolutional neural network (CNN) architecture of ResNet50. Attribution maps were obtained using the "Integrated Gradients" method.

RESULTS

The best performances were obtained with the SCP + RPC model achieving a mean area under the receiver operating characteristics curve (ROC AUC) of 0.94 (95% CI 0.92-0.96) for glaucoma, 0.90 (95% CI 0.86-0.94) for NAION and 0.96 (95% CI 0.96-0.97) for NC.

CONCLUSION

This study shows that deep learning architecture can classify NAION, glaucoma and normal OCTA images with a good diagnostic performance and may outperform the specialist assessment.

Quantitative approaches in multimodal fundus imaging: State of the art and future perspectives

When it first appeared, multimodal fundus imaging revolutionized the diagnostic workup and provided extremely useful new insights into the pathogenesis of fundus diseases. The recent addition of quantitative approaches has further expanded the amount of information that can be obtained. In spite of the growing interest in advanced quantitative metrics, the scientific community has not reached a stable consensus on repeatable, standardized quantitative techniques to process and analyze the images. Furthermore, imaging artifacts may considerably affect the processing and interpretation of quantitative data, potentially affecting their reliability. The aim of this survey is to provide a comprehensive summary of the main multimodal imaging techniques, covering their limitations as well as their strengths. We also offer a thorough analysis of current quantitative imaging metrics, looking into their technical features, limitations, and interpretation. In addition, we describe the main imaging artifacts and their potential impact on imaging quality and reliability. The prospect of increasing reliance on artificial intelligence-based analyses suggests there is a need to develop more sophisticated quantitative metrics and to improve imaging technologies, incorporating clear, standardized, post-processing procedures. These measures are becoming urgent if these analyses are to cross the threshold from a research context to real-life clinical practice.

Ultra-Widefield Swept-Source Optical Coherence Tomography Angiography in the Assessment of Choroidal Changes in Young Adults With Myopia

Purpose

To evaluate choroidal changes in young adults with myopia using ultra-widefield swept-source optical coherence tomography angiography (SS-OCTA).

Methods

This study enrolled 105 eyes of 105 participants who underwent SS-OCTA imaging (24 mm × 20 mm) centered on the fovea. Eyes were categorized as low myopia, moderate myopia, or high myopia. Choroidal thickness, choroidal capillary plexus (CCP) vessel density, and choroidal Sattler's and Haller's layer (CSHL) vessel density were analyzed in nine grids using built-in angiography analysis software.

Results

A significant decrease in choroidal thickness was found in most grids (P < 0.01) in high myopia. The CSHL vessel density also showed a significant decrease in most grids (P < 0.05) in high myopia. Choroidal thickness was negatively correlated with axial length in most grids (P < 0.05). Choroidal thinning was most evident in the macular grid (β = -22.55, P < 0.001). CSHL vessel density was negatively correlated with axial length in most grids (P < 0.05).

Conclusions

Choroidal changes could be quantified using ultra-widefield SS-OCTA. Choroidal thinning with increasing axial length indicated regional differences in eyes with myopia, which were most evident in the macular area. Decreased CSHL vessel density with increasing axial length also indicated regional differences in eyes with myopia.

Translational Relevance

This study explored choroidal changes with a wider field of view than has been currently available.

Comparison of widefield swept-source optical coherence tomography angiography with ultra-widefield fluorescein angiography for the evaluation of lesions in retinal vein occlusion

Background

To compare widefield swept-source optical coherence tomography angiography (SS-OCTA) with ultra-widefield fundus fluorescein angiography (UWF-FA) for detecting retinal vein occlusion (RVO) lesions.

Methods

Thirty-four eyes of 32 patients with treatment-naïve RVO were enrolled at Peking University People’s Hospital from September 2021 to March 2022. Patients were imaged with a UWF-FA (200°) and a widefield SS-OCTA using 24 × 20 mm scan single capture. Quantitative assessments of RVO lesions such as foveal avascular zone (FAZ) area and perimeter, non-perfusion areas (NPA), number of microaneurysms (MAs), capillary changes and collateral vessels were performed.

Results

The measurement of FAZ area and perimeter were comparable between SS-OCTA and UWF-FA (0.373 (range, 0.277–0.48) mm2 vs. 0.370 (range, 0.277–0.48) mm2, P = 0.818 and 2.480 (range, 2.011–2.998) vs. 2.330 (range, 2.027–2.807) mm, P = 0.536, respectively). Intraclass correlation coefficients (ICCs) of FAZ area and perimeter between SS-OCTA and UWF-FA was high (0.999, [0.997–0.999] and 0.996 [0.991–0.996], respectively), suggesting good agreement. The mean NPA area was larger on SS-OCTA than that on UWF-FA (89.977 ± 78.805 mm2vs. 87.944 ± 77.444 mm2, P = 0.037). The ICC of NPA area was also high (0.999, [0.999–1.000]). The median of total MA count was less on SS-OCTA than on UWF-FA (7 (range, 0–19) vs.12 (range, 0–23), P < 0.001). Agreement in detecting MAs between SS-OCTA and UWF-FA was found to be good (ICC = 0.920, [0.555–0.974]).The total capillary changes and collateral vessels count were less on UWF-FA than SS-OCTA (11 ± 9 vs 6 ± 7, P < 0.001 and 4 (range, 0–6) vs 0 (range, 0–0), P < 0.001, respectively). Agreement in detecting capillary changes and collateral vessels between OCTA and UWF-FA was found to be fair (ICC = 0.733, [0.081–0.905] and 0.564, [0.039–0.805], respectively).

Conclusion

Compared with UWF-FA, widefield SS-OCTA was found comparable or even superior in detecting FAZ, NPA, capillary changes and collateral vessels except MAs in RVO. Widefield SS-OCTA may offer a more efficient alternative to FA for diagnosis and monitoring RVO.

Multi-Center Repeatability of Macular Capillary Perfusion Density Using Optical Coherence Tomography Angiography

Background/Aims

This study was to determine the test-retest repeatability in quantifying macular capillary perfusion density (CPD, expressed as fractal dimension) using optical coherence tomography angiography (OCTA) in a multi-center setting.

Methods

OCTA data were obtained in self-reported healthy subjects from Bascom Palmer Eye Institute at the University of Miami (UM, N = 18) and the University of Pennsylvania (UPenn, N = 22). The right eye of each subject was imaged twice at the first visit and then again at an interval of one week to assess intra-visit and inter-visit repeatability. The macular area of the OCTA-derived capillary perfusion density (OCTA-CPD) was analyzed by custom-made image processing and fractal analysis software. Fractal analysis was performed on the skeletonized microvascular network to yield OCTA-CPD by box-counting to the fractal dimension (Dbox) in the superficial vascular plexus (SVP). Repeatability was assessed by three measures: within-subject standard deviation (Sw), coefficient of variation (CoV) of repeated measures, and intraclass correlation coefficient (ICC).

Results

OCTA-CPD from both sites (UM and UPENN) showed good to excellent intra-visit repeatability, as demonstrated by the Sw ≤0.004, CoVs ≤0.23%, and ICCs ≥0.61. Similarly, both sites had good to excellent inter-visit repeatability, as shown by the Sw ≤0.005, CoVs ≤0.28%, and ICCs ≥0.61. The Bland-Altman plots of the intra-visit and inter-visit measurements showed excellent agreements between the paired measurements with minimal biases.

Conclusion

Our data showed that comparable high repeatability of OCTA-CPD can be achieved in both research sites using the same device, scan protocol, and image analysis.

Optical coherence tomography angiography biomarkers of microvascular alterations in RVCL-S

Background

The brain and retina share many neuronal and vasculature characteristics. We investigated the retinal microvasculature in patients with a monogenic vasculopathy using optical coherence tomography angiography (OCTA). OCT-A is a novel precise non-invasive imaging method that may provide biomarkers suitable for diagnosis and follow-up of small vessel diseases.

Methods

In this exploratory cross-sectional study, eleven RVCL-S patients and eleven age-matched healthy control participants were included. The size of the foveal avascular zone (FAZ) and the vascular density of the superficial capillary networks in the retina were measured by OCT-A.

Results

The symptomatic and presymptomatic patients showed significantly lower vascular density values than controls in the foveal region [median (IQR) 18.2% (15.8-18.6) vs. 24.4% (21.5-26.8) (p < 0.001), 29.8% (29.6-30.8) vs. 33.2% (32.0-33.6) (p = 0.002), respectively]. The FAZ was significantly larger in the symptomatic RVCL-S patients than in the control group [13,416 square pixels [7,529-22,860] vs. 1,405 square pixels [1,344-2,470] (p < 0.001)]. No significant difference was identified in measurements of FAZ comparing presymptomatic and controls.

Conclusion

Our findings with OCT-A demonstrated that RVCL-S causes an increase in the size of the FAZ in symptomatic RVCL-S patients compared to healthy participants. Moreover, there is a decrease in vessel density in the superficial capillary networks in both symptomatic and presymptomatic patients. In the future, newly developed precise objective instruments such as OCT (-A) may provide important tools in determining disease activity for follow up of common small vessel diseases.

Optical Coherence Tomography Angiography to Estimate Early Retinal Blood Flow Changes after Uncomplicated Cataract Surgery

Background: To investigate macular microvascular changes after uncomplicated phacoemulsification surgery according to the cataract severity grade. Methods: Retrospective, cross-sectional study involving 23 eyes of 23 patients who underwent elective cataract extraction. All patients underwent routine ophthalmologic examination, including optical coherence tomography angiography (OCTA) at baseline (preoperative visit, T0) and seven days postoperatively (T7). OCTA scans were obtained with the spectral domain system Cirrus 5000 (Carl Zeiss Meditec, Inc., Dublin, CA, USA), and 3 mm × 3 mm raster fovea-centered scans were obtained to evaluate the superficial capillary plexus (SCP) vessel density, perfusion density, and foveal avascular zone (FAZ) parameters. Results: SCP perfusion density significantly increased from 28.3 ± 5.73% to 33.74 ± 4.13% after the surgery (p < 0.001). Similarly, SCP vessel density significantly increased from 15.14 ± 3.41 mm−1 to 18.14 ± 2.57 mm−1 after surgery (p < 0.001). The mean preoperative FAZ area significantly increased from 0.27 ± 0.12 mm to 0.24 ± 0.11 mm seven days postoperatively (p = 0.008). When comparing softer and harder cataracts, no significant variations in SCP vessel density, as well as SCP perfusion density parameters and the FAZ area, perimeter, and circularity index, were noted before and after surgery. Conclusions: Macular SPC vessel density and macular SCP perfusion density increase after uncomplicated cataract surgery regardless of the cataract severity.

Evaluating Distribution of Foveal Avascular Zone Parameters Corrected by Lateral Magnification and Their Associations with Retinal Thickness

Purpose

To examine the distribution of foveal avascular zone (FAZ) parameters, with and without correction for lateral magnification, in a large cohort of healthy young adults.

Design

Cross-sectional, observational cohort study.

Participants

A total of 504 healthy adults, 27 to 30 years of age.

Methods

Participants underwent a comprehensive ophthalmic examination including axial length measurement and OCT angiography (OCTA) imaging of the macula. OCT angiography images of combined superficial and deep retinal vessel plexuses were processed via a custom software to extract foveal avascular zone area (FAZA) and foveal density-300 (FD-300), the vessel density in a 300-μm wide annulus surrounding the FAZ, with and without correction for lateral magnification. Bland–Altman analyses were performed to examine the effect of lateral magnification on FAZA and FD-300, as well as to evaluate the interocular agreement in both parameters. Linear mixed-effects models were used to examine the relationship between retinal thicknesses and OCTA parameters.

Main Outcome Measures

The FAZA and FD-300, corrected for lateral magnification.

Results

The mean (standard deviation [SD]) of laterally corrected FAZA and FD-300 was 0.22 mm² (0.10 mm²) and 51.9% (3.2%), respectively. Relative to uncorrected data, 55.6% of corrected FAZA showed a relative change > 5%, whereas all FD-300 changes were within 5%. There was good interocular symmetry (mean right eye–left eye difference, 95% limits of agreement [LoA]) in both FAZA (0.006 mm², -0.05 mm², to 0.07 mm²) and FD-300 (-0.05%, -5.39%, to 5.30%). There were significant negative associations between central retinal thickness and FAZA (β = -0.0029), as well as between central retinal thickness and FD-300 (β = -0.044), with the relationships driven by inner, not outer, retina.

Conclusions

We reported lateral magnification adjusted normative values for FAZA and FD-300 in a large cohort of young, healthy eyes. Clinicians should strongly consider accounting for lateral magnification when evaluating FAZA. Good interocular agreement in FAZA and FD-300 suggests the contralateral eye can be used as control data.

Analysis of Microcirculation Changes in the Macular Area and Para-Optic Disk Region After Implantable Collamer Lens Implantation in Patients With High Myopia

Myopia has become an important public health problem to be solved urgently. Posterior chamber phakic implantable Collamer lens (ICL) implantation is one of the latest and safest products for myopia correction worldwide. This prospective cross-sectional case series aimed to observe changes in the macular retinal thickness, retinal nerve fiber layer (RNFL) thickness of para-optic disk region, and blood flow density after posterior ICL implantation in patients with high myopia using optical coherence tomography angiography (OCTA). A total of 67 eyes of 67 patients with high myopia, who underwent ICL implantation at The Affiliated Eye Hospital of Nanjing Medical University from January 2020 and December 2020, were included. The spherical equivalent (SE) of the operative eyes was &gt;−6.00 D. The changes in vision, intraocular pressure (IOP), SE, and vault were observed pre-operatively, and follow-up were performed 1 week, 1 month, and 3 months. OCTA was used to observe the changes in the CRT, retinal thickness of paracentral fovea, FAZ, superficial and deep retinal blood flow density in the macular area, RNFL thickness of para-optic disk region, and blood flow density before and after ICL implantation. The uncorrected distance visual acuity (UDVA) and best corrected distance visual acuity (CDVA) of the patients post-operation were significantly improved (P &lt; 0.001). The IOP increased in comparison with other time points at 1 week post-operation (P &lt; 0.05). There were no significant changes in CRT post-operation. The retinal thickness in the upper, lower, nasal, and temporal quadrants of the paracentral fovea increased significantly at 1 month and 3 months post-operation (P &lt; 0.05). The FAZ area at all postoperative time points were decreased (P &lt; 0.001). At 3 months post-operation, the blood flow density of the superficial and deep retinal layers in the upper, lower, and nasal macular area were significantly reduced (P &lt; 0.05). At 1 month post-operation, the RNFL thickness in the temporal para-optic disk region and blood flow density were significantly reduced (P = 0.001 and P &lt; 0.05, respectively). ICL implantation for highly myopic eyes led to an increase of the retinal thickness in the upper, lower, nasal, and temporal regions of the paracentral fovea; reduction of RNFL thickness in the temporal area of para-optic disk; decrease in FAZ area; and decrease in the blood flow density of some deep and superficial retinal layers as well as that of the temporal para-optic disk region.

Evaluation of the effect of uncomplicated cataract surgery on retina and optic disc: Optical Coherence Tomography Angiography Study

Purpose

The aim of the present study is to evaluate the effects of uncomplicated cataract surgery on microvascular structure of fovea, parafovea, optic disc, and peripapillary area with optical coherence tomography angiography (OCTA).

Methods

The study included 53 eyes of 53 patients, who undergone uncomplicated cataract surgery. The day before cataract surgery and at the 1st week, 1st month, 3rd month after surgery, best-corrected visual acuity, foveal avascular zone, acircularity index, superficial and deep foveal density, superficial and deep parafoveal density, central macular thickness, peripapillary retinal nerve fiber layer thickness value, and peripapillary vascular density were measured with OCTA.

Results

The mean age of the patients was 62.1 ± 7.2 years (range, 42–69 years) and the sex of the patients was 25 male and 28 female. The foveal avascular zone value was decreased compared to the preoperative value (p < 0.05). There was no significant change in acircularity index postoperatively (p > 0.05). There was a significant increase in superficial and deep foveal density and superficial and deep parafoveal density (p < 0.05). According to preoperative period, peripapillary retinal nerve fiber layer and inside disc capillary density of optic disc increased significantly (p < 0.05). There was no significant change in peripapillary vascular density postoperatively (p > 0.05).

Conclusions

Changes in the vascular density of the retina were detected with OCTA in eyes without ocular or systemic disease, which underwent uncomplicated cataract surgery. In the postsurgical period, OCTA provides important information in the evaluation and follow-up of these changes.

Effect of Mydriatic Administration On Retinal Hemodynamics in Glaucoma: An Optical Coherence Tomography Angiography Study

PRCIS

Pupillary dilation with 0.5% tropicamide and 2.5% phenylephrine resulted in a statistically significant decrease in foveal avascular zone (FAZ) metrics in glaucoma eyes. This observation emphasizes the critical role of pupillary status in interpreting glaucomatous vascular alterations detected by OCTA.

PURPOSE

To evaluate the influence of mydriatic eye drops on optical coherence tomography angiography (OCTA) parameters in patients with primary open-angle glaucoma (POAG).

METHODS

A total of 20 POAG eyes and 20 control eyes were recruited in the study. The imaging area on the fundus was visualized by AngioPlex (Cirrus 5000 HD-OCT; Carl Zeiss Meditec) using en face view of 3×3▒mm and 6×6▒mm preview scans. Images were generated before and after the instillation of topical 0.5% tropicamide and 2.5% phenylephrine. Optic nerve head (ONH) perfusion, ONH flux index, macular perfusion density, macular vessel density, and foveal avascular zone (FAZ) measurements were consecutively obtained for each session. Differences between the pre-and post-dilation measurements were evaluated in POAG patients and controls.

RESULTS

POAG eyes showed a statistically significant decrease in the FAZ area from a mean of 0.29▒mm2to 0.25▒mm2(P=0.037) and FAZ perimeter from a mean of 2.27▒mm to 2.09▒mm (P=0.045) in the OCTA 6×6▒mm scan area after tropicamide/phenylephrine instillation. Pre-and post-dilation measurements of ONH perfusion and ONH flux index were significantly lower in the glaucoma group compared to controls (P<0.05, for all).

CONCLUSION

Topical pupillary dilation with 0.5% tropicamide and 2.5% phenylephrine results in a statistically significant reduction in the FAZ area and FAZ perimeter in POAG eyes. Further OCTA studies are needed for the diagnostic value of vascular changes due to pupil dilation in glaucoma.

Influence of the Size of the Foveal Avascular Zone on Functional and Morphological Parameters in Patients with Early-Stage Diabetic Retinopathy

Purpose

To correlate functional and morphological parameters with foveal avascular zone’s (FAZ) size in diabetic patients with mild to moderate stage nonproliferative diabetic retinopathy.

Methods

Monocentric and prospective study of a consecutive case series of diabetic patients. Medical history, best corrected visual acuity (BCVA), best corrected high/low contrast visual acuity (BChcVA/BClcVA), mean sensitivity (MS) and mean defect (MD) in central visual field testing, and FAZ size in fluorescein-angiography (FAG) were recorded. Macular thickness (central point thickness CPT, central subfield thickness CST) and volume measurements (central subfield volume CSV, total macular volume) were taken from SD-OCT (6x6mm ETDRS-grid). Groups were categorised as presenting FAZ sizes smaller (G1) or larger (G2) than 0.35mm². Smallest (Q1) and largest quartiles (Q3) were also compared.

Results

Thirty-six of 40 patients were included. MS differed significantly between G1 (n = 6) and G2 (n = 30), and BChcVA/BClcVA as well as TMV correlated significantly with FAZ size in correlation analysis. Mean HbA1c tended to be lower in G1 than G2. Patients in G1 were slightly older than in G2. Treatment period with insulin was shorter in G1/Q1 than in G2/Q3. CPT and TMV were lower in G1/Q1 than in G2/Q3. Our analysis of the FAZ in terms of patient age, HbA1c, disease duration and insulin therapy duration revealed no significance. That lack of significance also applies to BCVA, MS, MD, CPT, CST and CSV.

Conclusion

As significantly associated, contrast sensitivity, central visual field parameters and potentially retinal thickness or volume seem to be suitable to detect early macular ischaemia. However, we failed to establish any correlation between FAZ and BCVA.

Macular and Optic Nerve Microvascular Alteration in Relation to Axial Length, by Optical Coherence Tomography Angiography (OCTA)

Aim

To study the effect of axial length (AL) on quantitative characterization of macular and optic nerve microvasculature using optical coherence tomography angiography (OCTA) in healthy individuals.

Methods

A cross-sectional study where participants were divided into 3 groups according to AL; A: ≤22.5 mm, B: 22.6–24.5 mm, C: >24.5 mm. Superficial vascular density (SVD), deep vascular density (DVD), foveal avascular zone (FAZ), and radial peripapillary capillary density (RPCD) were calculated using OCTA. Pearson correlation was run to identify the relation between AL and study parameters.

Results

One hundred and twelve eyes of 56 participants (20 males, 36 females) were included. Mean FAZ was 0.33 ± 0.15 mm², 0.27 ± 0.1 mm² and 0.28 ± 0.2 mm² in Groups A, B, and C, respectively (p value 0.073). No significant difference was found between 3 groups, as regards superficial foveal density and vessel density inside the disc. Deep foveal density was significantly lower in Group A in comparison to Groups B and C (p value 0.021 and 0.005, respectively). As for other parameters of SVD, DVD and RPCD, no significant difference was observed between Groups A and B; however, the same parameters were significantly lower in Group C when compared to Group A and B. AL was found to be negatively correlated to FAZ (r −0.191, p value 0.043) and most of parameters of SVD, DVD, and RPCD (p value < 0.0001).

Conclusion

Most of optic nerve and macular microvascular parameters were significantly lower in eyes with longer axial lengths when compared to those with shorter axial lengths. Moreover, most of these parameters were negatively correlated with AL.

Morphology and Vessel Density of the Macula in Preterm Children Using Optical Coherence Tomography Angiography

Background: Retinal morphology changes may be associated with prematurity and can lead to visual impairment. Optical coherence tomography angiography may contribute to understanding the pathomechanism of structural and vascular retinal impairment in premature children. The aim of this study was to assess an influence of prematurity, neonatal clinical characteristics, and a history of retinopathy of prematurity (ROP) on the morphology and retinal vascularity of macula in children. Methods: A case−control study of 123 preterm children and 86 full-term children was performed. The age of the subjects was 10.45 years (IQR: 8.12−12.77), while the age of the control group was 11.78 years (IQR: 8.81−13.79). Optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA, angio-OCT) were performed using RTVueXR Avanti (Optovue, Fremont, CA, USA). Ganglion cell complex (GCC), foveal thickness (FT), parafoveal thickness (PFT), size of foveal avascular zone (FAZ) in superficial plexus, superficial capillary vessel density (sVD), deep capillary vessel density (dVD), central choroidal thickness (CCT), and presence of macular hypoplasia were analyzed. The association between OCT/angio-OCT results and clinical characteristics including the degree of ROP and therapy requirements was assessed in preterm infants. Results: Foveal morphology was affected in preterm children with high incidence of foveal hypoplasia (24.77%). GCC was thinner in preterm children compared to controls: avgGG 93 μm vs. 100 μm, p < 0.001. No associations between GCC and gestational age (R = −0.085; p = 0.228) and birth weight (R = −0.054; p = 0.446) were found. FAZ in preterm group was smaller than in controls (0.13 ± 0.09 vs. 0.22 ± 0.09; p < 0.001). FAZ area correlated with gestational age (R = 0.456; p < 0.001) and birth weight (R = 0.472; p < 0.001). Deep vessel density in the fovea was higher in preterm children than in control group (p < 0.001). PFT was significantly lower in preterm children compared to control group. However, increased thickness in the fovea was noted in preterm children (p < 0.001). FT was inversely correlated with gestational age (R = −0.562; p < 0.001) and birth weight (R = −0.508, p < 0.001). CCT was lower in preterm children (312 μm vs. 337.5 μm, p < 0.001) Parameters of GCC and FT were higher in patients with ROP required treatment compared to patients without ROP and spontaneously regressed retinopathy. FAZ was smaller in patients with retinopathy than in preterm children without ROP. Conclusion: Prematurity has a significant negative impact on GCC, macular morphology, and vascularization. In premature children, decreased FAZ, increased FT, and vessel density were strongly associated with gestational age, birth weight, Apgar score, ROP stage, and treatment requirement. Optical coherence tomography angiography is a useful tool for detecting retinal changes in premature children.

Longitudinal evaluation of retinal thickness and OCTA parameters before and following silicone oil removal in eyes with macula-on and macula-off retinal detachments

BACKGROUND

To investigate the longitudinal retinal vascular and structural alterations by using OCTA following successful repair of retinal detachment (RD) by using silicone oil (SO) endotamponade.

METHODS

A prospective cohort study was performed on 24 eyes of 24 subjects; 17 of them with macula-off and seven with macula-on RD. At least four OCTA scans were generated for each study eye; two before and two after SO removal (SOR). At each session, retinal thickness (RT), vascular density (VD) in the superficial (SCP) and deep capillary plexuses (DCP) and foveal avascular zone(FAZ) size were measured within the fovea, parafovea and whole macular image. The changes in repeated measures of the same parameters especially before and after SOR were performed and compared within macula-on and macula-off groups and between fellow eyes.

RESULTS

"In the macula-off eyes, RT measurements within the whole macula, fovea and parafovea reduced as compared with their fellow eyes(p < 0.0001, p = 0.001 and p < 0.0001, respectively) and did not improve after SOR. Additionally, all of the whole macular, foveal, and parafoveal VD measurements at SCP and foveal VD at DCP were less than their fellow eyes after SOR (p = 0.026, p = 0.023 p = 0.026, and p = 0.002, respectively). In macula-on eyes, RT measurements decreased within the parafovea and whole macular area before SOR (p = 0.018 and p = 0.011, respectively) but improved after SOR. Also, VD measurements did not change during follow-up and were not statistically different than their fellow eyes (p > 0.05). FAZ enlargement was found in eyes with macular-off RD after SOR, whereas it was not observed with macular-on RD (p = 0.038and p = 0.237, respectively).

CONCLUSIONS

Treatment of macula-off RD with SO tamponade has been associated with vascular retinal abnormalities which did not improve following SOR. On the contrary, successful treatment of RD with SO tamponade in macula-on eyes VD measurements of SCP and DCP were not statistically different than their fellow eyes.

[Features of retinal blood flow in pregnant women with carbohydrate metabolism disorders]

Studying the condition of retinal blood flow in pregnant women with disorders of carbohydrate metabolism contributes to early detection of diabetic retinopathy (DR), which is necessary for timely treatment and preservation of high visual functions.

PURPOSE

To study retinal blood flow in pregnant women with disorders of carbohydrate metabolism using optical coherence tomography angiography (OCTA) in order to determine the criteria for manifestation and progression of DR.

MATERIAL AND METHODS

The study examined 203 pregnant women in the third trimester: 24 - with type 1 and 2 diabetes (T1D and T2D), 143 - with gestational diabetes (GD), and 36 apparently healthy women with physiological pregnancy that comprised the control group. OCTA imaging was performed on RTVue XR Avanti ("Optovue", USA) system using HD Angio Retina 6.0 mm² scan protocol. The whole image vessel density (wiVD), foveal vessel density (FVD), and foveal avascular zone (FAZ) area in the superficial capillary plexus were studied.

RESULTS

FVD was significantly lower in pregnant women with diabetes than in pregnant women with GD and in the control group, prompting an assumption that retinal microvascular regulation changes because of chronic disturbances of carbohydrate metabolism in such patients and due to development of microangiopathy. Statistically significant increase in FAZ area and decrease in wiVD were revealed in patients with DR compared to data from the group of pregnant women with diabetes but without DR, in the absence of differences in FVD. In 2 patients with T1D and no ophthalmoscopic signs of DR, OCTA revealed areas of nonperfusion in the posterior pole of the eye.

CONCLUSION

OCTA can help identify areas of retinal nonperfusion in the posterior pole of the eye in pregnant women with diabetes and no ophthalmoscopic signs of DR, and determine objective indications for timely retinal laser coagulation.

Research progress of UWFFA and OCTA in retinal vein occlusion: A review

Retinal vein occlusion (RVO) is a retinal vascular disease that severely impairs the visual function of patients. Observing the changes of retinal blood vessels before and after treatment is of great significance for the prognostic evaluation of RVO. The rapid development and widespread use of fundus imaging technique, especially ultra-wide-angle fundus fluorescein angiography (UWFFA) and optical coherence tomography angiography (OCTA) have made our observation of the retinal blood vessels of RVO more comprehensive and meticulous. In this paper, we reviewed the latest research progress of UWFFA and OCTA in RVO.

Optical coherence tomography-angiography in diabetic retinopathy diagnosis and monitoring

Optical coherence tomography-angiography is a modern noninvasive method of 3D imaging and quantitative analysis of the retinal and choroidal microvasculature. It allows detecting manifestation and progression of diabetic retinopathy, planning treatment and evaluating its results.Optical coherence tomography angiography expands our understanding of microvascular changes in retinal vascular plexuses at different disease stages and deepens the understanding of its pathogenesis.

Impact of image averaging on vessel detection using optical coherence tomography angiography in eyes with macular oedema and in healthy eyes

Purpose

To assess the repeatability of multiple automatic vessel density (VD) measurements and the effect of image averaging on vessel detection by optical coherence tomography angiography (OCTA).

Methods

An observational study was conducted in a series of healthy volunteers and patients with macular oedema. Five sequential OCTA images were acquired for each eye using the OptoVue HD device. The effect of the averaging of the 5 acquisitions on vessel detection was analysed quantitatively using a pixel-by-pixel automated analysis. In addition, two independent retina experts qualitatively assessed the change in vessel detection in averaged images segmented in 9 boxes and compared to the first non-averaged image.

Results

The automatic VD measurement in OCTA images showed a good repeatability with an overall mean intra-class correlation coefficient (ICC) of 0.924. The mean ICC was higher in healthy eyes compared to eyes with macular oedema (0.877 versus 0.960; p < 0.001) and in the superficial vascular plexus versus the deep vascular complex (0.967 versus 0.888; p = 0.001). The quantitative analysis of the effect of the averaging showed that averaged images had a mean gain of 790.4 pixels/box, located around or completing interruptions in the vessel walls, and a mean loss of 727.2 pixels/box. The qualitative analysis of the averaged images showed that 99.6% of boxes in the averaged images had a gain in vessel detection (i.e., vessels detected in the averaged image but not in the non-averaged image). The loss of pixels was due to a reduction in background noise and motion artifacts in all cases and no case of loss of vessel detection was observed.

Conclusion

The automatic VD measurement using the OptoVue HD device showed a good repeatability in 5 acquisitions in a row setting. Averaging images increased vessel detection, and in about a third of boxes, decreased the background noise, both in healthy eyes and, in a greater proportion, in eyes with macular oedema.

Parafoveal Microvascular Alterations in Ocular and Non-Ocular Behҫet's Disease Evaluated With Optical Coherence Tomography Angiography

Purpose

To compare quantitative optical coherence tomography angiography (OCT-A) measurements of the parafoveal microvasculature in retinal capillary plexuses among Behҫet uveitis (BU) patients, non-ocular Behҫet's disease (NOBD) patients, and healthy volunteers (HVs).

Methods

Sixty-eight subjects were enrolled in this prospective observational cross-sectional study. OCT-A imaging was performed using the Heidelberg Engineering Spectralis OCT. A custom algorithm was developed to calculate the vessel density (VD) in three retinal vascular layers: deep capillary plexus, intermediate capillary plexus, and superficial vascular plexus. The foveal avascular zone (FAZ) and acircularity index were calculated for the whole retinal vascular complex.

Results

We analyzed one eye from 21 BU patients (age, 51 ± 10 years), 23 NOBD patients (age, 48 ± 14 years), and 22 HVs (age, 44 ± 13 years). One-way multivariate analysis of covariance showed a statistically significant difference in VD among the three groups when combining the layers after controlling for scan quality (P < 0.001). The VD was lowest in the BU group and highest in the HV group in all layers. The FAZ area was also statistically significant different among the groups (P < 0.005), with the largest FAZ areas in BU patients and smallest FAZ areas in the HV group. However, no statistically significant difference was found for the acircularity index.

Conclusions

The parafoveal microvasculature is affected not only in BU patients but also in NOBD patients. Most deviations in the retinal microcirculation in Behҫet patients were found in the deeper layers of the retina by using the quantitative VD measurement.

Evaluation of the Macular and Choroidal Perfusion in Healthy Turkish Population Using Optical Coherence Tomography Angiography

PURPOSE

To investigate the effect of age- and sex-related differences on macular and choroidal perfusion in healthy Turkish individuals by optical coherence tomography angiography (OCTA).

METHODS

Two hundred-eight eyes of 116 healthy Turkish individuals (60 females and 56 males, mean age 40.35 ± 12.64 years) were included in this study. OCTA was performed on a 3 × 3-mm region on the macula. The superficial macula wholeimage vessel density (wiVD), foveal VD and parafoveal VD vessel density, foveal avascular zone (FAZ) as well as choriocapillaris flow index (CFI) were quantified.

RESULTS

The mean vessel density was 53.1% ± 2.8% in superficial macula wiVD, 31.7% ± 6.9% in superficial foveal VD and 55.2% ± 3.4% in superficial parafoveal VD for 3 × 3-mm OCTA images. Analysis of 3 × 3-mm scan has revealed a mean value of FAZ area was 0.313 ± 0.112 mm2. The mean CFI for 3 × 3-mm scan was 1.937 ± 0.059. A significant decrease was observed in the mean values of wiVD, parafoveal VD and CFI with age (p &lt; 0.001, p = 0.001, and p &lt; 0.001, respectively), with average yearly reductions of 0.3%, 0.4% and 0.4%, respectively. However, there was no correlation between age and foveal VD (p &gt; 0.05). The FAZ area has shown an age-dependent annual increment, showing an average of 1.26%. The parafoveal VD and FAZ area were significantly higher in females than males (p = 0.027 and p = 0.015, respectively) while other parameters seemed similar (p &gt; 0.05 for all).

CONCLUSIONS

Our results suggest that age- and sex-related variations were effective on macular and choroidal perfusion. These normative values obtained using OCTA may be clinically useful to the evaluation of retinal and choroidal disorders.

Repeatability of Manual Measurement of Foveal Avascular Zone Area in Optical Coherence Tomography Angiography Images in High Myopia

PURPOSE

To analyze the repeatability of manual measurement of foveal avascular zone (FAZ) area in an optical coherence tomography angiography (OCTA) image in high myopia.

METHODS

This study comprised patients with high myopia and controls. Two consecutive FAZ areas of the superficial and deep capillary plexus were obtained using OCTA. The intraclass correlation coefficient (ICC) and coefficient of variation (CV) were assessed, and univariate and multivariate generalized linear mixed models were conducted to identify factors related to repeatability.

RESULTS

Thirty eyes with high myopia and 34 eyes of healthy subjects were included in the study. The mean age in high myopia and control subjects was 55.5 and 60.8 years, respectively, the mean spherical equivalent was -9.98 and -0.55 diopters, and the mean axial length was 28.0 and 23.9 mm. The ICCs of FAZ area of the superficial capillary plexus (SCP) were 0.891 and 0.919, while the CVs were 8.8% and 8.5%. In measurement of the deep capillary plexus, the ICCs were 0.788 and 0.907, while the CVs were 11.2% and 11.0%, which were acceptable but exhibited lower repeatability than those of SCP. Multivariate analyses showed that older age (p = 0.030) and greater axial length (p = 0.005) were significantly associated with lower repeatability of SCP FAZ area measurements. In addition, greater axial length (p = 0.044) was a significant factor for lower repeatability of deep capillary plexus FAZ area measurements.

CONCLUSIONS

Manual measurement of FAZ area using OCTA exhibited relatively good repeatability for high myopia. Age and axial length affected repeatability and should be considered when analyzing FAZ areas in high myopia patients.

The Impact of Chronic Heart Failure on Retinal Vessel Density Assessed by Optical Coherence Tomography Angiography in Children with Dilated Cardiomyopathy

(1) Introduction: The aim of this study is to assess retinal vessel density (VD) in the superficial capillary plexus layer (SP) and deep capillary plexus layer (DP) in children with chronic heart failure (CHF) in the course of dilated cardiomyopathy (DCM) using optical coherence tomography angiography (OCTA). (2) Methods: Thirty children with CHF due to DCM lasting more than six months, with an enlarged left ventricle and impaired left ventricular systolic function (left ventricular ejection fraction (LVEF) ≤ 55%), were enrolled to have both their eyes assessed for this study. Mean age of the children was 9.9 ± 3.57 years. The control group consisted of an additional 30 children without CHF (mean age 11.27 ± 3.33 years) matched for age and gender against the study group. All participants underwent transthoracic echocardiography to measure LVEF using Simpson method. Blood serum was tested for N-terminal-pro-brain natriuretic peptide (NT-proBNP) marker value. All children underwent OCTA with evaluation of the foveal avascular zone (FAZ), whole superficial vessel density (wsVD), foveal superficial vessel density (fsVD), parafoveal superficial vessel density (psVD), whole deep vessel density (wdVD), foveal deep vessel density (fdVD), parafoveal deep vessel density (pdVD), whole thickness (WT), foveal thickness (FT), and parafoveal thickness (PFT). (3) Results: Retinal VD in SP was significantly lower in children with CHF as compared to the controls. The following SP parameters in the study group were statistically significantly lower than these same measurements for the control group. Details, with study group findings quantified first, include wsVD (46.2% vs. 49.83%, p < 0.05), fsVD (18.07% vs. 24.15%, p < 0.05), and psVD (49.24% vs. 52.51%, p < 0.05). The WT (311.03 micrometers (μm) vs. 323.55 μm, p < 0.05), FT (244.57 μm vs. 256.98 μm, p < 0.05), and PFT (320.63 μm vs. 332.02 μm, p < 0.05). No significant differences in DP retinal VD were found between the two groups. No statistically significant differences in the FAZ were found. The fsVD and FT were correlated with biometry and the age of the study participants. There was a correlation between FAZ and FT (p < 0.001). There were no correlations between retinal VD in both plexuses and refractive error, sex, NT-proBNP, and LVEF. (4) Conclusions: In children with CHF in the course of DCM as compared to the control group, significantly decreased retinal VD in SP was observed. The results of our study indicate that measurements of the OCTA may be a useful diagnostic method in children with chronic heart failure, but it is necessary to conduct further studies in larger groups of participants and long-term observation of these patients.

Repeatability of Optical Coherence Tomography Angiography Measurements in Patients with Retinal Vein Occlusion

PURPOSE

To analyze the repeatability of vessel density (VD) measurements and manual foveal avascular zone (FAZ) measurements using optical coherence tomography angiography (OCTA) in patients with retinal vein occlusion (RVO) without macular edema.

METHODS

The study population consisted of patients with RVO and central macular thickness <300 μm. For each subject, measurements were performed twice with a 5-minute interval. The intraclass correlation coefficient (ICC) and coefficient of variation (CV) were calculated to analyze the repeatability of results obtained with the OCTA device. To identify factors related to repeatability, we performed Pearson correlation analyses based on the CV of potential factors.

RESULTS

A total of 48 eyes were included in the study. The ICCs of the VDs in superficial capillary plexus (SCP) and the deep capillary plexus (DCP) were 0.748 and 0.665, respectively, and the CVs of the VDs in SCP and DCP were 9.1% and 12.6%, respectively. The ICCs associated with the FAZ of the superficial layer (SFAZ) and that of the deep layer (DFAZ) were 0.965 and 0.956, respectively, and the CV of the SFAZ and DFAZ were 8.8% and 9.7%, respectively. From Pearson correlation analyses, OCTA quality was significantly correlated with the CV of the VDs of SCP and DCP. However, there were no variables that were significantly correlated with the CV of SFAZ and DFAZ, including OCTA quality.

CONCLUSIONS

VD measurements in the SCP layer using OCTA exhibited good repeatability, and VD measurements in the DCP layer exhibited relatively low repeatability compared to that of SCP layer measurements in patients with RVO without macular edema after treatment with bevacizumab. Manual measurement of the FAZ area in both SCP and DCP layers resulted in good repeatability. In addition, the repeatability of VD measurements in SCP and DCP layers was correlated with OCTA image quality.

The agreement between optical coherence tomography angiography and non-mydriatic retinal camera in estimating the optic nerve head parameters and relations with the peripapillary vessel density in primary open-angle glaucoma

BACKGROUND/OBJECTIVES

To investigate the agreement between optical coherence tomography angiography (OCT-A) and non-mydriatic retinal camera (NMRC) in estimating the optic nerve head (ONH) parameters and evaluate the associations between peripapillary vessel density (VD) with ONH parameters assessed by both devices.

METHODS

The OCT-A and NMRC images of 262 participants (138 eyes were diagnosed with POAG, 63 were glaucoma suspect, and 61 were healthy subjects) were screened retrospectively. The vertical cup-to-disc ratio (VCDR), cup-to-disc area ratio (CDAR), rim area (RA), disc area (DA), and cup volume (CV) were recorded using both devices. Peripapillary VD data were also recorded using OCT-A. The intraclass correlation coefficient (ICC) and Bland-Altman plots were obtained to investigate the agreement between the devices. Age- and intraocular pressure (IOP)-corrected associations between the VD and ONH parameters measured by the two devices were analyzed using linear regression models.

RESULTS

ICC revealed excellent agreement for VCDR and CDAR, but poor agreement for RA, DA, and CV (ICC = 0.801, 0.793, 0.445, 0.298, and 0.527, respectively). The Bland-Altman plots showed poor agreement for VCDR and CDAR with a large span of limits of agreement (0.500 and 0.528, respectively) and significant proportional biases (P < 0.05). VD was found to be strongly associated with the VCDR and CDAR measurements of both devices (P < 0.001), but the associations were stronger for the measurements of NMRC.

CONCLUSIONS

The disagreement between the devices should be considered in clinical practice. The associations between the VD and ONH parameters proved once again the importance of the ONH parameters in terms of the management of glaucoma patients.

Interchangeability of retinal perfusion indices in different-sized angiocubes: An optical coherence tomography angiography study in diabetic retinopathy

Purpose

To evaluate the differences in vascular indices in different scan sizes of optical coherence tomography angiography (OCTA) images in normal persons versus persons with diabetic retinopathy.

Methods

OCTA scans of diabetic patients and age-matched controls were performed by a single operator. Automated quantification of vascular indices of the superficial plexus was analyzed in two angiocubes of 3 × 3 mm and 6 × 6 mm, respectively. The agreement was analyzed with the intraclass correlation coefficient (ICC) and Bland-Altman plots.

Results

Forty-eight eyes with DR, 36 eyes with no diabetic retinopathy (No DR), and 26 eyes of age-matched normals were scanned. The foveal avascular zone (FAZ) area and perimeter were highly reliable and interchangeable in both angiocubes of the healthy eyes (ICC 0.94, 0.75), No DR (ICC 0.92, 0.85), and DR eyes (ICC 0.97, 0.89). The vessel density (VD) and perfusion density (PD) showed excellent agreement in normal (ICC 0.89, 0.80) and No DR eyes (ICC 0.92, 0.81). But, only fair ICC was observed in DR eyes (0.56, 0.42).

Conclusion

The FAZ area and perimeter showed excellent reproducibility. The macular perfusion parameters are not interchangeable despite automated estimation. The variability is more with changes in the vascular network like DR. This variability should be considered while comparing different scans.

Changes in the Foveal Avascular Zone Area and Retinal Vessel Density after Anti-VEGF Therapy for Neovascular Age-Related Macular Degeneration

PURPOSE

To investigate changes in the foveal avascular zone (FAZ) area and retinal vessel density (VD) in the macula of patients receiving multiple anti-vascular endothelial growth factor (VEGF) therapy for neovascular age-related macular degeneration (N-AMD).

METHODS

This study included 54 eyes of 54 treatment-naïve N-AMD patients. Thirty-three eyes were treated with intravitreal aflibercept injections, and 21 eyes were treated with intravitreal ranibizumab injections. Unaffected fellow eyes (54 eyes) were used as controls. All image scans were acquired after the macular architecture had recovered with drying up of the subretinal fluid/hemorrhage after treatment.

RESULTS

Both the superficial and deep FAZ areas were significantly larger in the aflibercept group than in the control group. The VD was also significantly reduced in the aflibercept group.

CONCLUSIONS

Prolonged and repeated anti-VEGF therapy may cause an increase in the FAZ area and a decrease in the VD in patients with N-AMD, indicating ischemic damage.

Remodeling of Retinal Microcirculation Is Associated With Subclinical Arterial Injury in Hypertensive Children

[Figure: see text].

Preservation of the Foveal Avascular Zone in Achromatopsia Despite the Absence of a Fully Formed Pit

Purpose

To examine the foveal avascular zone (FAZ) in patients with congenital achromatopsia (ACHM).

Methods

Forty-two patients with genetically confirmed ACHM were imaged either with Optovue's AngioVue system or Zeiss's Plex Elite 9000, and the presence or absence of a FAZ was determined. For images where a FAZ was present and could be confidently segmented, FAZ area, circularity index, and roundness were measured and compared with previously published normative values. Structural optical coherence tomography images were acquired to assess the degree of foveal hypoplasia (number and thickness of inner retinal layers present at the fovea).

Results

A FAZ was present in 31 of 42 patients imaged (74%), although no determination could be made for 11 patients due to poor image quality (26%). The mean ± SD FAZ area for the ACHM retina was 0.281 ± 0.112 mm², which was not significantly different from the previously published normative values (P = 0.94). However, their FAZs had decreased circularity (P < 0.0001) and decreased roundness (P < 0.0001) compared to the normative cohort. In the patients with ACHM examined here, the FAZ area decreased as the number and thickness of the retained inner retinal layers increased.

Conclusions

Our data demonstrate that despite the presence of foveal hypoplasia, patients with ACHM can have a FAZ. This is distinct from other conditions associated with foveal hypoplasia, which generally show an absence of the FAZ. In ACHM, FAZ formation does not appear to be sufficient for complete pit formation, contrary to some models of foveal development.

Retinal vascular metrics difference by comparison of two image acquisition modes using a novel OCT angiography prototype

PURPOSE

To assess the different impact of two enface OCTA image simultaneously acquired by means of a new prototype of Spectral-Domain Optical Coherence Tomography Angiography (SD-OCTA) on quantitative retinal vascular metrics.

METHODS

In this prospective observational cross-sectional study 28 healthy subjects were enrolled. Macular (3x3 mm) OCTA images were acquired for all participants using Solix Fullrange OCT (Optovue Inc, Freemont CA, USA). The main outcome measurements were: Perfusion density (PD), vessel length density (VLD), and vessel diameter index (VDI) of both superficial capillary plexus (SCP) and deep capillary plexus (DCP), and choriocapillaris (CC) total flow-deficits area. Quantitative retinal vascular metrics were measured on binarized and skeletonized OCTA images by comparing not averaged and fast automated multiple averaged en face OCTA images.

RESULTS

In both SCP and DCP, PD significantly increased (p = 0,005 and p = 0,030, respectively), and VLD significantly decreased (p<0,001 and p = 0,004, respectively), and VDI increased (p<0,001 and p = 0,068, respectively), and total CC flow deficits area significantly decreased (p<0,001) by averaging multiple OCTA images.

CONCLUSIONS

In this study, we found a significant difference of quantitative retinal metrics by comparing two different image acquisition modes using a novel and fully automated averaging OCTA system in young healthy subjects.

Optical coherence tomography angiography of central serous chorioretinopathy patients' response to breath-holding manoeuvre

PURPOSE

To demonstrate through the use of optical coherence tomography angiography (OCTA) that normal vasoreactivity cannot be monitored in central serous chorioretinopathy (CSR) patients in the presence of vasoactive stimuli owing to hypoxia caused by the breath-holding manoeuvre (BHM).

METHODS

This cross-sectional study included a total of 210 eyes, including 70 CSR patients (70 symptomatic eyes, 70 asymptomatic eyes) and 70 control group. Images of the macula (3 × 3 mm) and the optic disc (4.5 × 4.5 mm) were obtained at the baseline and after BHM using OCTA. The change in vascular parameters in the OCTA after BHM was evaluated in CSR patients and the control group.

RESULTS

In the symptomatic eyes of CSR patients, the mean whole image vessel density (VD) in the superficial capillary plexus decreased from 48.0 ± 3.5% under baseline conditions to 46.0 ± 4.5% after BHM (p < 0.01), and the mean whole VD in the deep capillary plexus decreased from 47.9 ± 8.0% under baseline conditions to 46.9 ± 6.7% after BHM (p < 0.01). The OCTA after BHM revealed a decrease in the mean whole image VD of the optic disc in both symptomatic (50.4 ± 2.1% to 49.6 ± 2.0%, p < 0.05) and asymptomatic (50.9 ± 1.8% to 50.4 ± 1.9%, p < 0.05) eyes of CSR patients. No difference for any mean VD of the control group was seen between the baseline and after BHM. Outer retinal flow areas increased significantly after BHM compared with the baseline in both eyes of CSR patients.

CONCLUSION

These results suggest that CSR pathogenesis is related to an imbalance in local vascular regulation and the sympathetic activity of the autonomic nervous system. This technique constitutes a new way of studying retinal vascular changes and may be applied to CSR patients.

Foveal Avascular Zone Measurement Via Optical Coherence Tomography Angiography and its Relationship With the Visual Field in Eyes With Open-angle Glaucoma

PRECIS

The foveal avascular zone (FAZ) in optical coherence tomography angiography is significantly correlated with retinal inner layer thickness, Humphrey field analyzer (HFA) 10-2 sensitivity threshold, and mean deviation (MD) value in open-angle glaucoma patients.

PURPOSE

The purpose of this study was to measure the FAZ area using optical coherence tomography angiography and investigate its relationship with retinal inner layer thickness and visual field defects in eyes with open-angle glaucoma.

PARTICIPANTS AND METHODS

A total of 52 eyes with open-angle glaucoma from 52 patients. FAZ area was measured using optical coherence tomography angiography in angio-macula mode. Thicknesses of retinal nerve fiber layer (RNFL), ganglion cell layer plus inner plexiform layer (GCL+IPL), and ganglion cell complex (GCC) were determined using a 7 mm×7 mm macular (V) map via 3D-OCT. Correlations of FAZ area with sensitivity threshold measurements, foveal threshold (FT), and MD value in the HFA10-2 visual field were analyzed for each inner retinal layer.

RESULTS

FAZ area was 0.26±0.07 mm; overall mean thicknesses were 19.14±6.55 μm (RNFL), 57.34±5.93 µm (GCL+IPL), and 75.87±10.96 μm (GCC); mean FT was 35.23±3.15 dB, and sensitivity threshold was 20.81±7.22 dB in the HFA10-2 visual field. FAZ area was significantly correlated with the thickness of individual retinal layers in the entire field (RNFL, P<0.001; GCL+IPL, P<0.001; GCC, P<0.001), sensitivity threshold (P=0.01), FT (P<0.001), and MD value (P=0.011).

CONCLUSION

FAZ area was significantly negatively correlated with retinal inner layer thickness, sensitivity threshold, FT, and MD value in the HFA10-2 visual field.

Superficial and Deep Foveal Avascular Zone Area Measurement in Healthy Subjects Using Two Different Spectral Domain Optical Coherence Tomography Angiography Devices

Purpose

To compare the area of the foveal avascular zone (FAZ) in the superficial and deep retinal layers using two different spectral-domain optical coherence tomography angiography (OCTA) devices.

Methods

A cross-sectional comparative study was conducted to obtain macular OCTA images from healthy subjects using Optovue RTVue XR Avanti (Optovue, Inc, Fremont, CA) and Spectralis HRA+OCTA (Heidelberg Engineering, Heidelberg, Germany). Two independent trained graders measured the FAZ area using automated slab segmentation. The FAZ area in the superficial and deep retinal layers were compared.

Results

Twenty-three eyes of 23 subjects were included. The graders agreement was excellent (>0.86) for all measurements. The mean FAZ area was significantly larger at the superficial retinal layer as compared to the deep retinal layer on both devices (0.31 ± 0.08 mm2 vs 0.26 ± 0.08 mm2 in Optovue and 0.55 ± 0.16 mm2 vs 0.36 ± 0.13 mm2 in Spectralis, both P< 0.001). The mean FAZ area was significantly greater in the superficial and deep retinal layers using Spectralis as compared to Optovue measurements (P< 0.001 for both comparisons).

Conclusion

In contrast to previous reports, the FAZ area was larger in the superficial retina as compared to deep retinal layers using updated software versions. Measurements from different devices cannot be used interchangeably.

Agreement Between Standard Optical Coherence Tomography and Optical Coherence Tomography-Based Angiography in Estimating Retinal Nerve Fiber Layer Thickness

Objectives

To investigate the agreement between optical coherence tomography (OCT) and OCT-based angiography (OCT-A) in estimating retinal nerve fiber layer thickness (RNFLT) and evaluate the associations between peripapillary vessel density (VD) and RNFLT measurements obtained with both devices.

Materials and Methods

The AngioVue (Optovue Inc., Fremont, CA, USA) and Spectralis (Heidelberg Engineering, Heidelberg, Germany) images of 325 patients were screened retrospectively. RNFLT values were recorded using both devices. The intraclass correlation coefficient (ICC) and Bland-Altman plots were obtained to investigate the agreement between the devices. Age- and intraocular pressure-corrected associations between VD and RNFLT measured by the two devices were analyzed using linear regression models.

Results

ICC revealed excellent agreement for global, superior, inferior, and temporal RNFLT and good agreement for the nasal quadrant (ICC=0.895, 0.936, 0.923, 0.887, and 0.614, respectively). The Bland-Altman plots showed poor agreement for all measurements with a large span of limits of agreement and significant proportional bias (p<0.05). VD was found to be strongly associated with the RNFLT measurements of both devices (p<0.001).

Conclusion

The disagreement between the devices should be considered in clinical practice, and the data should not be used interchangeably. The association of the peripapillary VD with RNFLT using both devices indicated that RNFLT assessed by the AngioVue could be used in glaucoma management along with VD.

INTRAVITREAL ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR TREATMENT AT 2-MONTH INTERVALS REDUCES FOVEAL AVASCULAR ZONE ENLARGEMENT AND VISION LOSS IN RADIATION MACULOPATHY: A Pilot Study

PURPOSE

To evaluate, in eyes with radiation maculopathy, the effect of 2-month-interval anti-vascular endothelial growth factor therapy on best-corrected visual acuity and foveal avascular zone (FAZ) enlargement using optical coherence tomography angiography.

METHODS

Consecutive treatment-naive patients with radiation maculopathy after proton beam irradiation for choroidal melanoma were retrospectively included. Clinical and optical coherence tomography angiography data at baseline and the 6-month visit were recorded. Two independent observers measured FAZ area manually on 3 × 3-mm optical coherence tomography angiography images of the superficial capillary plexus and deep capillary plexus. Patients were encouraged to follow strictly a 2-month-interval intravitreal anti-vascular endothelial growth factor treatment by either bevacizumab or ranibizumab. Findings were analyzed based on the adherence to the treatment scheme.

RESULTS

According to the adherence to the bimonthly anti-vascular endothelial growth factor treatment protocol, patients were categorized into 3 groups: treatment protocol (n = 19, strict adherence), variable intervals (n = 11, intervals other than 2 months), and no treatment (n = 11). The estimated radiation dose to the foveola in each group was 49 ± 16, 46 ± 17, and 46 ± 18 cobalt gray equivalent, respectively (P = 0.85). For the entire cohort, best-corrected visual acuity loss (P < 0.02) and FAZ enlargement (P < 0.0001) were observed over 6 months. Best-corrected visual acuity loss was significantly less pronounced in the treatment-protocol group than in the variable-interval and no-treatment groups (P = 0.007 and P = 0.004). The FAZ enlargement was lower in the treatment-protocol group compared with the variable-interval group for both superficial capillary plexus (P = 0.029) and deep capillary plexus (P = 0.03), and to the no-treatment group for the deep capillary plexus only (P = 0.016).

CONCLUSION

Decrease in best-corrected visual acuity and FAZ enlargement on optical coherence tomography angiography occurred over 6 months in eyes with radiation maculopathy and were significantly reduced under 2-month-interval anti-vascular endothelial growth factor therapy.

Optical Coherence Tomography Angiography in Type 1 Diabetes Mellitus. Report 1: Diabetic Retinopathy

Purpose

The purpose of this study was to evaluate specifically in type 1 diabetes mellitus (DM) individuals the relationship between perifoveal superficial capillary plexus (SCP) parameters assessed by optical coherence tomography angiography (OCTA) and diabetic retinopathy (DR) grade.

Methods

Cross-sectional analysis of a large scale prospective OCTA trial cohort (ClinicalTrials.gov NCT03422965). A total of 1186 eyes (593 individuals), 956 type 1 DM eyes (478 patients), and 230 control eyes (115 healthy volunteers) were included in this study. DR stage was graded according to the International Classification. OCTA imaging was performed with a commercially available device (Cirrus HD-OCT). Vessel density (VD), perfusion density (PD), and foveal avascular zone (FAZ) area, perimeter and circularity measurements were quantified in the SCP and receiver operating characteristic (ROC) curves were constructed for each OCTA parameter.

Results

VD and PD (in both 3 × 3 and 6 × 6 mm captures) were inversely associated with DR stage (P < 0.001 in all cases) in a multiple regression analysis after controlling by age, gender, signal strength index, axial length, and DM duration. Greater FAZ area and perimeter and conversely lower circularity measurements were observed as DR severity increased in both scanning protocols (P < 0.05 in all cases).

Conclusions

In type 1 DM individuals, OCTA provides an objective, continuous, and reliable method for accurate quantification of VD, PD, and FAZ parameters in the SCP, which ultimately correlate with DR stages.

Translational Relevance

Objective OCTA measurements of the retinal microvasculature could substitute the clinical DR classification in patients with type 1 DM, identify patients at risk of DR progression, and inform treatment decisions to modify the evolution of the disease.

Morphological Characteristics of Normal Foveal Avascular Zone by Optical Coherence Tomography Angiography

Purpose

To provide quantitative measurements for the foveal avascular zone (FAZ) and to describe its morphological characteristics by optical coherence tomography angiography (OCT-A).

Design

Cross-sectional observational case series.

Methods

Healthy volunteers were recruited and evaluated using Triton-DRI SS-OCT Angiography. A 4.5 × 4.5 mm square was evaluated by OCT-A center around the fovea. Superficial and deep capillary plexus were identified, and different quantitative measurements were conducted along with categorization of the FAZ pattern.

Results

Eighty-two eyes (41 volunteers) were evaluated. Mean age was 30.59 ± 7.6 years (23–42 years). Mean subcentral retinal thickness was 200.1 ± 5.66 um (192–210 um). The number of terminal vessels was variable (range, 8–11). Mean maximum terminal vessel-to-vessel intervening distance was 527.8 ± 60.3 um (471–674 um). Mean minimum terminal vessel-to-vessel intervening distance was 296.7 ± 45.8 um (233–373 um). Mean maximum horizontal diameter of FAZ (superficial) was 716.17 ± 124.09 um, while mean maximum vertical diameter of FAZ (superficial) was 667.76 ± 131.28 um. Mean maximum horizontal diameter of FAZ (deep) was 823.19 ± 144.92 um, while mean maximum vertical diameter of FAZ (deep) was 794.03 ± 150.28 um. OCT-A detected different FAZ patterns; horizontally oval configuration in 32 eyes (39%), rounded configuration in 24 eyes (29.3%), pentagon configuration in 14 eyes (17.1%), and vertically oval and nonspecific configuration in 6 eyes each (7.3%).

Conclusion

OCT-A could efficiently provide both quantitative and qualitative assessment of normal FAZ; such characterizations were difficult by standard FAZ assessment procedures like FFA.

Reliability of foveal avascular zone measurements in eyes with retinal vein occlusion using optical coherence tomography angiography

BACKGROUND

To evaluate the reliability of foveal avascular zone (FAZ) area measurements using optical coherence tomography angiography (OCTA) in eyes with retinal vein occlusion (RVO).

METHODS

Twenty-five OCTA exams of patients with RVO were evaluated retrospectively. Three examiners performed manual measurements of the FAZ, and interrater and intrarater reliability were obtained.

RESULTS

The intraclass correlation coefficient (ICC) for interrater reliability for individual measurements was 0.62 (moderate) with a 95% confidence interval (CI) of 0.40 to 0.79 (p < 0.001). The ICC (95% CI) for intrarater reliability was 0.92 (0.82 to 0.96) for rater A, 0.96 (0.91 to 0.98) for B, and 0.88 (0.76 to 0.94) for C (p < 0.001). In all subanalyses including presence of edema and type of occlusion, interrater reliability was poor/moderate, and intrarater reliability was good/excellent.

CONCLUSION

The FAZ varies significantly among eyes with RVO, so measurements obtained using OCTA should be analyzed with caution due to the moderate level of reliability among different examiners.