Projection-resolved Optical Coherence Tomography Angiography Research Articles

Signal attenuation-compensated projection-resolved OCT angiography.

Projection artifacts are a significant limitation of optical coherence tomographic angiography (OCTA). Existing techniques to suppress these artifacts are sensitive to image quality, becoming less reliable on low-quality images. In this study, we propose a novel signal attenuation-compensated projection-resolved OCTA (sacPR-OCTA) algorithm. In addition to removing projection artifacts, our method compensates for shadows beneath large vessels. The proposed sacPR-OCTA algorithm improves vascular continuity, reduces the similarity of vascular patterns in different plexuses, and removes more residual artifacts compared to existing methods. In addition, the sacPR-OCTA algorithm better preserves flow signal in choroidal neovascular lesions and shadow-affected areas. Because sacPR-OCTA processes the data along normalized A-lines, it provides a general solution for removing projection artifacts agnostic to the platform.

Perforating scleral vessels adjacent to myopic choroidal neovascularization achieved a poor outcome after intravitreal anti-VEGF therapy.

This study aimed to summarize the features of perforating scleral vessels (PSVs) in patients with myopic choroidal neovascularization (CNV) (mCNV) using optical coherence tomography angiography (OCTA) and to identify the associations with the response after intravitreal anti-vascular endothelial growth factor (anti-VEGF) therapy. A consecutive series of naïve patients who had mCNV and received intravitreal anti-VEGF therapy with a follow-up duration of 12 months or more were enrolled. The prevalence, location, and branches of PSVs were analyzed. Projection-resolved OCTA (PR-OCTA) was used to analyze the neovascular signals between CNV and PSVs. Best corrected visual acuity (BCVA) and central macular thickness (CMT) were measured. The proportion of CMT change relative to baseline was used to assess therapeutic response. A total of 44 eyes from 42 patients with mCNV were enrolled. PSVs were identified in 41 out of 44 eyes. Branches were identified in the PSVs of 24 eyes (57.14%), and 20 eyes did not have PSV branches (47.62%). In eight eyes (18.18%), PSVs were adjacent to mCNV, and in 36 eyes (81.82%), PSVs were not adjacent to mCNV. After anti-VEGF therapy for mCNV, BCVA increased (F = 6.119, p < 0.001) and CMT decreased (F = 7.664, p < 0.001). In the eyes where PSVs were adjacent to mCNV, BCVA improvements (F = 7.649, p = 0.009) were poor, and changes in CMT were small. The eyes with PSVs adjacent to mCNV showed poor therapeutic responses after intravitreal anti-VEGF therapy.

Macular Vascular Imaging and Connectivity Analysis Using High-Resolution Optical Coherence Tomography.

PurposeTo characterize macular blood flow connectivity in vivo using high-resolution optical coherence tomography (HighRes OCT).MethodsCross-sectional, observational study. Dense (6-µm interscan distance) perifoveal HighRes OCT raster scans were performed on healthy participants. To mitigate the limitations of projection-resolved OCT-angiography, flow and structural data were used to observe the vascular structures of the superficial vascular complex (SVC) and the deep vascular complex. Vascular segmentation and rendering were performed using Imaris 9.5 software. Inflow and outflow patterns were classified according to vascular diameter and branching order from superficial arteries and veins, respectively.ResultsEight eyes from eight participants were included in this analysis, from which 422 inflow and 459 outflow connections were characterized. Arteries had direct arteriolar connections to the SVC (78%) and to the intermediate capillary plexus (ICP, 22%). Deep capillary plexus (DCP) inflow derived from small-diameter vessels succeeding ICP arterioles. The most prevalent outflow pathways coursed through superficial draining venules (74%). DCP draining venules ordinarily merged with ICP draining venules and drained independently of superficial venules in 21% of cases. The morphology of DCP draining venules in structural HighRes OCT is distinct from other vessels crossing the inner nuclear layer and can be used to identify superficial veins.ConclusionsVascular connectivity analysis supports a hybrid circuitry of blood flow within the human parafoveal macula.Translational RelevanceCharacterization of parafoveal macular blood flow connectivity in vivo using a precise segmentation of HighRes OCT is consistent with ground-truth microscopy studies and shows a hybrid circuitry.

Optical Coherence Tomography Angiography Biomarkers Predict Anatomical Response to Bevacizumab in Diabetic Macular Edema.

PurposeTo identify biomarkers that may predict an early anatomical response to the treatment of diabetic macular edema (DME) with intravitreal bevacizumab (IVB) by means of optical coherence tomography angiography (OCTA).MethodsThis study is a retrospective study of treatment-naïve patients with DME who underwent 6 × 6 mm OCTA imaging of the macula at baseline and after three monthly IVB injections. Thirty-six eyes of 23 patients were included. Eyes that demonstrated evidence of an early anatomical response, consisting of a >10% decrease in central macular thickness (CMT) (n = 18), were compared with those eyes that failed to show such an improvement (n = 18).ResultsAt baseline, early-response eyes had worse starting best-corrected visual acuity (BCVA, LogMAR 0.84 ± 0.41 versus LogMAR 0.51 ± 0.15, p = 0.004) and a larger CMT (490 ± 135 µm versus 356 ± 33 µm, p = 0.001), but smaller foveal avascular zones (FAZ) (0.309 ± 0.098mm versus 0.413 ± 0.095 mm, p = 0.003) compared with eyes that proved refractory to three monthly injections of IVB. The vascular density (VD) in both the foveal superficial and deep capillary plexuses was significantly greater in eyes that showed an early-treatment response compared with eyes that were non-responders (24.86 ± 6.90% versus 19.98 ± 7.13%, p = 0.045 and 32.30 ± 4.88% versus 26.95 ± 7.25%, p = 0.028, respectively). Early-treatment response to IVB was predicted by starting CMT (r2= 0.266, p = 0.001), FAZ size (r2= 0.234, p = 0.003), and VD in the superficial parafovea (r2= 0.217, p = 0.004) and deep fovea (r2= 0.157, p = 0.037).ConclusionProjection-resolved OCTA may be useful in predicting an early anatomical response of DME to treatment with IVB.

Longitudinal analysis of quantitative biomarkers using projection-resolved OCT angiography in retinal vein occlusion

Longitudinal analysis of quantitative biomarkers using projection-resolved OCT angiography in retinal vein occlusion

Exploring the Relationship Between Multilayered Choroidal Neovascularization and Choriocapillaris Flow Deficits in AMD.

PurposeWe used optical coherence tomography angiography to test the hypothesis that more complex, multilayered choroidal neovascular (CNV) membranes in AMD are associated with worse flow deficits (FD) in the choriocapillaris.MethodsRetrospective, cross-sectional study including 29 eyes of 29 subjects with neovascular AMD. En face choriocapillaris images were compensated for signal attenuation using the structural OCT slab and signal normalization based on a cohort of healthy subjects. We binarized the choriocapillaris using both local Phansalkar and global MinError(I) methods and quantified FD count, FD density, and mean FD size in the entire area outside the CNV, in the 200-µm annulus surrounding the CNV, and in the area outside the annulus. We used projection-resolved optical coherence tomography angiography to quantify CNV complexity, including highest CNV flow height, number of flow layers, and flow layer thickness. We explored the relationship between CNV complexity and choriocapillaris FD using Spearman correlations.ResultsThe highest CNV flow signal significantly correlated with lower FD count (P < 0.01), higher FD density (P < 0.05), and higher mean FD size (P < 0.05) in the area outside the annulus and the entire area outside the CNV using both Phansalkar and MinError(I). Within the annulus, CNV complexity was not consistently correlated with choriocapillaris defects.ConclusionsCNV vascular complexity is correlated with choriocapillaris FD outside the CNV area, providing evidence for the importance of choriocapillaris dysfunction in neovascular AMD, as well as the potential role of choroidal ischemia in the pathogenesis of complex CNV membranes.

Plexus-specific retinal capillary avascular area in exudative age-related macular degeneration with projection-resolved OCT angiography

ObjectiveTo detect the plexus-specific retinal capillary avascular area in exudative age-related macular degeneration (EAMD) with projection-resolved optical coherence tomography angiography (PR-OCTA).Methods and analysisIn this prospective cross-sectional single centre study, eyes...

GENESIS OF RETINAL–CHOROIDAL ANASTOMOSIS IN MACULAR TELANGIECTASIA TYPE 2

To longitudinally characterize structural/angiographic findings of retinal-choroidal anastomosis (RCA) in macular telangiectasia Type 2 (MacTel2). A combined retrospective/prospective review of patients with MacTel2 with >2 visits and >2 months follow-up, including examination, fundus photography, fluorescein angiography, spectral-domain optical coherence tomography, and projection-resolved optical coherence tomography angiography. There were 24 eyes of 12 patients with a mean age of 61.1 (±7.3 [SD]) years and median follow-up of 447 (range 81-1,511) days. There were five eyes diagnosed with new RCA after not having any previously. Retinal-choroidal anastomosis was diagnosed in 8 (33%) eyes initially and eventually 13 (54%). In the eight eyes initially diagnosed with RCA, the number of RCAs and outer retinal hyperrflective lesions increased over the follow-up. The RCAs were found in clusters, generally temporal to the fovea. Retinal-choroidal anastomosis was uniformly associated with complete retinal subsidence, defined as the loss of outer nuclear layer substance such that the middle retinal layers sank down toward the retinal pigment epithelium (RPE), and was also present in each case. Each RCA colocalized with a region of hyperreflectivity, previously termed an outer retinal hyperreflective lesion. There was a lack of fluorescein leakage, lipid, hemorrhage, or any structural correlates with fluid exudation, and no signs of subretinal/subretinal pigment epithelium neovascularization. De novo RCA development seems to be associated with retinal subsidence, and after RCAs form, they increase in number and topographic distribution over time. Initially after formation, there was no sign of exudation. These data suggest the descent of the deep capillary plexus occurs with RCA, devoid of subretinal/subretinal pigment epithelium neovascularization in MacTel2.

CHARACTERIZING RETINAL–CHOROIDAL ANASTOMOSIS IN MACULAR TELANGIECTASIA TYPE 2 WITH OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

To characterize structural and angiographic findings in macular telangiectasia Type 2 (MacTel 2) and examine associations with visual acuity. MacTel 2 patients with complete ophthalmologic examination, including fundus photography, autofluorescence, spectral-domain optical coherence tomography, and projection-resolved optical coherence tomography angiography, were retrospectively evaluated. There were 43 eyes of 22 patients with a mean age 63.9 (±10.3) years. Six patients had diabetes. Twenty-one eyes (48.8%) had retinal-choroidal anastomoses (RCAs) without any evidence of neovascularization extending laterally in a plane above or below the retinal pigment epithelium. None of the eyes had hemorrhage, lipid, or signs of subretinal exudation. When present, an average of 55 (±33.7) individual RCAs were clustered primarily in temporal juxtafoveal region of involved eyes. Right-angle veins were seen in all 21 eyes with RCAs, and hyperpigmentation was present in 18 (P < 0.001 for both). A conical collection of hyperreflective material spanning from Bruch membrane past external limiting membrane of ≥200-μm basal diameter was found in 21 eyes and labeled outer retinal hyperreflective lesion. Retinal-choroidal anastomoses occurred in clusters, often within the outer retinal hyperreflective lesion. This lesion colocalized with focal thinning of the outer nuclear layer and was surrounded by a larger defect in the ellipsoid zone. The presence of diabetes (P = 0.015), outer retinal hyperreflective lesion (P = 0.006), RCA (P = 0.005), and ellipsoid zone defect extent (P < 0.001) were associated with decreased visual acuity. Retinal-choroidal anastomoses occur in eyes with MacTel 2 without signs of exudation. Retinal-choroidal anastomoses occur in numerous clusters particularly in the temporal juxtafoveal macula. Diabetes, ellipsoid zone defect extent, RCAs, and the outer retinal hyperreflective lesion predict poorer vision in MacTel 2.

Macular Vascularity in Ischemic Optic Neuropathy Compared to Glaucoma by Projection-Resolved Optical Coherence Tomography Angiography

To compare macular vasculature in patients with primary open-angle glaucoma (POAG) and atrophic nonarteritic anterior ischemic optic neuropathy (NAION). Prospective, cross-sectional study. Thirty-seven eyes with moderate and advanced POAG, 19 eyes with atrophic NAION, and 40 eyes of normal subjects were imaged using optical coherence tomography angiography (OCT-A). Macular ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer (RNFL) thicknesses were measured in addition to macular superficial and deep vasculature after projection removal using custom software. Linear models showed that while averaged peripapillary RNFL and macular GCC were not different between NAION and POAG eyes, both were significantly thinner than control eyes. Whole image macular superficial vessel density was significantly lower in NAION and glaucoma eyes (P= .003 and <.001, respectively) than in normal eyes, with lower vessel density in glaucoma than in NAION eyes (P= .01). Whole image and parafoveal deep macular vessels in glaucoma eyes (21.0%±8.7%, 24.4%±9.6%) were significantly lower than in control eyes (27.4%±8.6%, 31.9%±10.6%) (P= .01 and P= .01, respectively). No significant differences in deep vessels were observed between NAION and control eyes. Glaucomatous eyes had lower temporal and inferior parafoveal deep vasculature values than NAION eyes (P= .007 and .03, respectively). In NAION and POAG with similar RNFL and macular damage, macular OCT-A shows less involvement of superficial and deep vascular plexus in NAION in contrast to POAG, which might show a primary vascular insult in addition to secondary vascular damage due to ganglion cell damage.

Detection of Reduced Retinal Vessel Density in Eyes with Geographic Atrophy Secondary to Age-Related Macular Degeneration Using Projection-Resolved Optical Coherence Tomography Angiography

To compare retinal vessel density in eyes with geographic atrophy (GA) secondary to age-related macular degeneration (AMD) to age-matched healthy eyes by using projection-resolved optical coherence tomography angiography (PR-OCTA). Prospective cross-sectional study. Study participants underwent macular 3-× 3-mm OCTA scans with spectral domain OCTA. Reflectance-compensated retinal vessel densities were calculated on projection-resolved superficial vascular complex (SVC), intermediate capillary plexus (ICP), and deep capillary plexus (DCP). Quantitative analysis using normalized deviation compared the retinal vessel density in GA regions, 500-μm GA rim regions, and non-GA regions to similar macular locations in control eyes. Ten eyes with GA and 10 control eyes were studied. Eyes with GA had significantly lower vessel density in the SVC (54.8 ± 2.4% vs. 60.8 ± 3.1%; P<0.001), ICP (34.0 ± 1.5% vs. 37.3 ± 1.7%; P=0.003) and DCP (24.4 ± 2.3% vs. 28.0 ± 2.3%; P < 0.001) than control eyes. Retinal vessel density within the GA region decreased significantly in SVC, ICP, and DCP. Retinal vessel density in the GA rim region decreased in SVC and ICP but not in DCP. The non-GA region did not significantly deviate from normal controls. Eyes with GA had significantly reduced photoreceptor layer thickness; but similar nerve fiber layer, ganglion cell complex, inner nuclear layer, and outer plexiform layer thickness. Eyes with GA have reduced retinal vessel density in SVC, ICP, and DCP compared to those in controls. Loss is greatest within regions of GA. Vessel density may be more sensitive than retinal layer thickness measurement in the detection of inner retinal change in eyes with GA.

MULTILEVEL ISCHEMIA IN DISORGANIZATION OF THE RETINAL INNER LAYERS ON PROJECTION-RESOLVED OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

To examine the relationship between ischemia and disorganization of the retinal inner layers (DRIL). Cross-sectional retrospective study of 20 patients (22 eyes) with diabetic retinopathy presenting to a tertiary academic referral center, who had DRIL on structural optical coherence tomography (OCT) using Spectralis HRA + OCT (Heidelberg Engineering, Heidelberg, Germany) and OCT angiography with XR Avanti (Optovue Inc, Fremont, CA) on the same day. Optical coherence tomography angiography images were further processed to remove flow signal projection artifacts using a software algorithm adapted from recent studies. Retinal capillary perfusion in the superficial capillary plexuses, middle capillary plexuses, and deep capillary plexuses, as well as integrity of the photoreceptor lines on OCT was compared in areas with DRIL to control areas without DRIL in the same eye. Qualitative assessment of projection-resolved OCT angiography of eyes with DRIL on structural OCT demonstrated significant perfusion deficits compared with adjacent control areas (P < 0.001). Most lesions (85.7%) showed superimposed superficial capillary plexus and/or middle capillary plexus nonperfusion in addition to deep capillary plexus nonflow. Areas of DRIL were significantly associated with photoreceptor disruption (P = 0.035) compared with adjacent DRIL-free areas. We found that DRIL is associated with multilevel retinal capillary nonperfusion, suggesting an important role for ischemia in this OCT phenotype.

Longitudinal vasculature changes in branch retinal vein occlusion with projection-resolved optical coherence tomography angiography.

To analyze vascular changes in branch retinal vein occlusion (BRVO) using projection-resolved optical coherence tomography angiography (PR-OCTA). We reviewed 30 consecutive eyes of 30 cases with BRVO retrospectively. PR-OCTA was performed during the acute, intermediate, and remission phases when anti-vascular endothelial growth factor drugs suppress cystic changes. The main outcome measures were vessel density (VD) and retinal thickness changes in the superficial capillary plexus (SCP), intermediate capillary plexus (ICP), and deep capillary plexus (DCP). The VDs did not change longitudinally in the SCP and DCP during the follow-up period. The VD was significantly (p = 0.0105) greater in the ICP during remission than the acute phase. The full retinal thickness (internal limiting membrane [ILM] to retinal pigment epithelium [RPE]) and inner retinal thickness (ILM to inner plexiform layer [IPL]) decreased significantly (p = 0.0002 and p = 0.0014, respectively) during the follow-up period. When the inner retina was thinner than 117μm, the VD in the ICP increased significantly (p = 0.045) during the follow-up period. When the inner retinal layer did not become thinner, the VD in the ICP remained unchanged. PR-OCTA showed the three distinct vascular plexuses in BRVO. The VDs remained unchanged during the follow-up period in the SCP and DCP but increased significantly in the ICP during remission. Inner retinal thinning might cause increases in the VD in the ICP because of projection artifacts and segmentation errors despite using PR-OCTA.

Projection-Resolved Optical Coherence Tomography Angiography of the Peripapillary Retina in Glaucoma

To detect plexus-specific peripapillary retinal perfusion defects in glaucoma, using projection-resolved optical coherence tomography angiography (PR-OCTA). Prospective cross-sectional study. One eye each of 45 perimetric glaucoma participants and 37 age-matched normal participants were scanned using 4.5-mm OCTA scans centered on the disc. The PR-OCTA algorithm removed flow projection artifacts in OCT angiograms. Five en face OCTA slabs were analyzed: nerve fiber layer plexus (NFLP), ganglion cell layer plexus (GCLP), superficial vascular complex (SVC [NFLP+ GCLP]), deep vascular complex (DVC), and all plexi combined. Peripapillary retinal capillary density (CD) and vessel density (VD) were calculated using a reflectance-compensated algorithm. Focal capillary dropout could be visualized more clearly in the NFLP than in the other slabs. The NFLP, SVC, and all-plexus CD in the glaucoma group were significantly lower (P < 0.001) than in the normal group, but no significant differences in GCLP-CD and DVC-CD appeared between the 2 groups. Both NFLP-CD and SVC-CD had excellent diagnostic accuracy, as measured by the area under the receiver operating characteristic curve (AROC= 0.981 and 0.976), correlation with visual field mean deviation (Pearson r= 0.819 and 0.831), and repeatability (intraclass correlation coefficients= 0.947 and 0.942). Performances of NFLP-VD and SVC-VD were similar to the corresponding CD parameters. In this glaucoma group, reduction in perfusion was more pronounced in superficial layers of the peripapillary retina (NFLP and SVC) than in the deeper layers. Reflectance-compensated CD and VD parameters for both NFLP and SVC could be useful in the clinical management of glaucoma.

Projection-Resolved Optical Coherence Tomography Angiography Parameters to Determine Severity in Diabetic Retinopathy.

The purpose of this study was to assess projection-resolved optical coherence tomography angiography (PR-OCTA) vessel density (VD) and foveal avascular zone (FAZ) in determining severity within diabetic retinopathy (DR) and their accuracy in identifying high-risk DR patients. This was a retrospective study with 72 eyes of 52 DR patients, assessing the VD and FAZ area of the superficial capillary plexus (SCP) and deep vascular plexus (DVP), for both 3 × 3-mm and 6 × 6-mm scans between the DR groups (mild to moderate, severe and proliferative DR [PDR]). For accuracy, the severe and PDR groups were merged, representing the high-risk DR group for receiver operator characteristic analysis. VD of OCTA images with and without PR were compared. In mild to moderate, severe, and PDR groups, there were 31, 21, and 20 eyes, respectively. PR-OCTA improved VD analysis only in the DVP and particularly in advanced DR stages (P = 0.042). In the 3 × 3-mm PR scans, all superficial and deep parameters were significantly different between severe and PDR groups (P ≤ 0.020), but only the mean VD of SCP and DVP was also significant between the mild to moderate and severe groups (P ≤ 0.007). In the 6 × 6-mm scans, the superficial VD, deep VD, and superficial FAZ were significantly different between the severe and PDR groups (P ≤ 0.029). The superficial VD and deep VD of the 3 × 3-mm scans were good parameters for detecting high-risk patients (area under the curve = 0.829 and 0.895, respectively). PR-OCTA improved VD analysis of DVP. The 3 × 3-mm SCP and DVP VD were the most accurate in detecting high-risk DR.

RETINAL-CHOROIDAL ANASTOMOSIS IN MACULAR TELANGIECTASIA TYPE 2.

To investigate the deep retinal vascular changes potentially present in macular telangiectasis Type 2 (MacTel 2) with projection resolved optical coherence tomography angiography including volume rendering. Retrospective consecutive evaluation of patients with MacTel 2 in a community-based retinal referral practice with a comprehensive ophthalmologic examination to include optical coherence tomography and projection-resolved optical coherence tomography angiography with volume rendering. Main outcome measures were the characterization of vessel presence and anatomical arrangement in the outer retina. There were 26 eyes of 13 patients with a mean age of 64.9 (±11.3) years, and 6 were men. The mean visual acuity was logMAR 0.4 (Snellen equivalent 20/50). No eye had signs of choroidal neovascularization or exudation. Focal hyperpigmentation was seen in 13 (50%) and right-angle veins in 17 (65%) eyes. Retinal-choroidal anastomoses were seen in 17 (65%) eyes. These anastomoses typically occurred in multiple clusters of small vessels. The presence of anastomoses was associated with pigment (P < 0.001), although the anastomoses did not necessarily colocalize with the pigment, and right-angle veins (P < 0.001), which were found in every eye with a retinal-choroidal anastomosis. Retinal-choroidal anastomoses were commonly observed in eyes with MacTel 2 using projection-resolved optical coherence tomography angiography. One animal model for MacTel 2 uses very low-density lipoprotein receptor mutant mice and shows multiple retinal-choroidal anastomoses in the disease pathogenesis as well. These findings suggest MacTel 2 is more than just a neurodegenerative disease with secondary vascular abnormalities, as the choroid may be involved in the disease process.

Automated Quantification of Nonperfusion Areas in 3 Vascular Plexuses With Optical Coherence Tomography Angiography in Eyes of Patients With Diabetes

Diabetic retinopathy (DR) is a leading cause of vision loss that is managed primarily through qualitative clinical examination of the retina. Optical coherence tomography angiography (OCTA) may offer an objective and quantitative method of evaluating DR. To quantify capillary nonperfusion in 3 vascular plexuses in the macula of eyes patients with diabetes of various retinopathy severity using projection-resolved OCTA (PR-OCTA). Cross-sectional study at a tertiary academic center comprising 1 eye each from healthy control individuals and patients with diabetes at different severity stages of retinopathy. Data were acquired and analyzed between January 2015 and December 2017. Foveal avascular zone area, extrafoveal avascular area (EAA), and the sensitivity of detecting levels of retinopathy. The study included 39 control individuals (20 women [51%]; mean [SD] age, 43.41 [19.37] years); 16 patients with diabetes without retinopathy (8 women [50%]; mean [SD] age, 56.50 [12.43] years); 23 patients with mild to moderate nonproliferative DR (18 women [78%] ; mean [SD] age, 62.48 [10.55] years); and 32 patients with severe nonproliferative DR or proliferative DR (12 women [38%]; mean age, 53.41 [14.05] years). Mean (SD) foveal avascular zone area was 0.203 (0.103) mm2 for control individuals, 0.192 (0.084) mm2 for patients with diabetes without retinopathy, 0.243 [0.079] mm2 for mild to moderate nonproliferative DR, and 0.359 (0.275) mm2 for severe nonproliferative DR or proliferative DR. Mean (SD) EAA in whole inner retinal slab in these groups, respectively, were 0.020 (0.031) mm2, 0.034 (0.047) mm2, 0.038 (0.040) mm2, and 0.237 (0.235) mm2. The mean (SD) sum of EAA from 3 segmented plexuses in each of the respective groups were 0.103 (0.169) mm2, 0.213 (0.242) mm2, 0.451 (0.243) mm2, and 1.325 (1.140) mm2. With specificity fixed at 95%, using EAA in inner retinal slab, the sensitivity of detecting patients with diabetes from healthy control individuals was 28% (95% CI, 18%-40%), 31% for patients with DR (95% CI, 19%-45%), and 47% for patients with severe DR (95% CI, 29%-65%) from whole inner retinal EAA. With the sum of EAA from 3 individual plexuses, the sensitivities were 69% (95% CI, 57%-80%), 82% (95% CI, 70%-91%), and 97% (95% CI, 85%-100%), respectively. Avascular areas were not associated with signal strength index. The commercial vessel density from the 2-plexus scheme distinguished the groups with lower sensitivity and were dependent on SSI. Automatically quantified avascular areas from a 3-layer segmentation scheme using PR-OCTA distinguished levels of retinopathy with a greater sensitivity than avascular areas from unsegmented inner retinal slab or measurements from a commercially available vessel density in 2-layer scheme. Additional studies are needed to investigate the applicability of nonperfusion parameters in clinical settings.

Volume-Rendered Projection-Resolved OCT Angiography: 3D Lesion Complexity Is Associated With Therapy Response in Wet Age-Related Macular Degeneration.

PurposeTo explore whether quantitative three-dimensional (3D) analysis of choroidal neovascularization (CNV) using projection-resolved optical coherence tomography angiography (PR-OCTA) is associated with treatment response in neovascular age-related macular degeneration (nAMD).MethodsRetrospective, cross-sectional study of 51 eyes of 49 patients undergoing individualized anti-VEGF therapy for nAMD. Patients were classified as “good” or “poor” responders, requiring injections at less or more frequently than 6-week intervals, respectively. Cross-sectional PR-OCTA images were used to measure the distance between Bruch's membrane and highest CNV flow signal. The number of flow layers within the CNV and the distance between these flow layers (CNV flow thickness) were also analyzed. Two masked, independent graders measured the PR-OCTA parameters. We used 3D volume-rendered PR-OCTA to confirm the number of CNV flow layers and further evaluate CNV complexity.ResultsPoor responders had significantly greater distance between Bruch's membrane and highest CNV flow signal (P < 0.01), greater number of CNV flow layers (P = 0.022), and greater CNV flow thickness (P < 0.01). Volume-rendered PR-OCTA images confirmed the number of CNV flow layers.ConclusionsCross-sectional and 3D volume-rendered PR-OCTA provides a novel approach for quantifying CNV complexity. Our results suggest that CNV acquiring more complex 3D vascular structure are associated with more frequent long-term anti-VEGF therapy, reflecting a particular pattern of normalization or complex CNV remodeling process that characterizes these less responsive eyes.

Acute macular neuroretinopathy associated with influenza vaccination with decreased flow at the deep capillary plexus on OCT angiography

PurposeWe report a case of acute macular neuroretinopathy (AMN) following routine annual inactivated influenza vaccination. Projection-resolved optical coherence tomography angiography (PR-OCTA) was used to analyze the retinal capillary flow within the AMN lesion. ObservationsOur patient reported visual symptoms of her right eye nine days after routine annual influenza vaccination. Multimodal imaging revealed small vessel peripheral vasculitis and AMN in the affected eye. Infectious, immunologic, and hypercoagulable etiologies were investigated and excluded. PR-OCTA B-scans within the AMN lesion demonstrated reduced flow in the deep capillary plexus (DCP) at baseline with relatively improved flow signal in the DCP on follow up, 3 weeks later. Conclusions and importanceWe report a new association of AMN following routine inactivated influenza immunization. Recent influenza vaccination should be included in the differential diagnosis for patients presenting with AMN. PR-OCTA demonstrated compromised DCP flow in the AMN lesion which has not been previously described.

Plexus-Specific Detection of Retinal Vascular Pathologic Conditions with Projection-Resolved OCT Angiography

To evaluate the projection-resolved (PR) optical coherence tomography angiography (OCTA) algorithm in detecting plexus-specific vascular abnormalities in retinal pathologies. Cross-sectional observational clinical study. Patients diagnosed with retinal vascular diseases and healthy volunteers. Eyes were imaged using an OCT system operating at 840 nm and employing the split-spectrum amplitude decorrelation algorithm. A novel algorithm suppressed projection artifacts inherent to OCTA. The volumetric scans were segmented and visualized on different plexuses. Qualitative observation of vascular abnormalities on both cross-sectional and en face PR-OCTA images. Eight illustrative cases are reported. In cases of diabetic retinopathy, retinal vessel occlusion, and retinitis pigmentosa, PR-OCTA detected retinal nonperfusion regions within deeper retinal plexuses not visualized by conventional OCTA. In age-related macular degeneration, cross-sectional PR-OCTA permitted the classification of choroidal neovascularization, and, in a case of retinal angiomatous proliferation, identified a vertical vessel contiguous with the deep capillary plexus. In macular telangiectasia, PR-OCTA detected a diving perifoveal vein and delineated subretinal neovascularization. Application of PR-OCTA promises to improve sensitive, accurate evaluation of individual vascular plexuses in multiple retinal diseases.