Optical Coherence Tomographic Angiography Imaging in Age-Related Macular Degeneration.

Optical coherence tomographic angiography (OCTA) is emerging as a rapid, noninvasive imaging modality that can provide detailed structural and flow information on retinal and choroidal vasculature. This review contains an introduction of OCTA and summarizes the studies to date on OCTA imaging in age-related macular degeneration

Perfusion Deficits in Diabetes Without Retinopathy Localize to the Perivenular Deep Capillaries Near the Fovea on OCT Angiography

Purpose: To localize early capillary perfusion deficits in patients with diabetes mellitus (DM) without clinical diabetic retinopathy (DR) using averaged OCT angiography (OCTA). Design: Retrospective cross-sectional study. Participants: Patients with DM without DR and healthy controls. Methods: We measured perfusion deficits in the full retina, superficial capillary plexus (SCP), and deep capillary plexus (DCP) on averaged 3 × 3-mm OCTA images. Perfusion deficits were defined as the percentage of retinal tissue located >30 μm from blood vessels, excluding the foveal avascular zone (FAZ). One eye from each patient was selected based on image quality. We measured deficits in the parafoveal region, the 300 μm surrounding the FAZ, and 300 to 1000 μm surrounding the FAZ. If a capillary layer within one of these regions was significantly different in DM without DR compared with controls, we further characterized the location of perfusion deficit as periarteriolar, perivenular, or the capillaries between these 2 zones. Main Outcome Measures: Location of increased perfusion deficits in patients with DM without DR compared with controls. Results: Sixteen eyes from 16 healthy controls were compared with 16 eyes from 16 patients with DM without DR (age 45.1 ± 10.7 and 47.4 ± 15.2 years respectively, P = 0.64). Foveal avascular zone area and perfusion deficits in the entire parafovea and the 300 to 1000-μm ring around the FAZ were not significantly different between groups (P > 0.05 for all). Perfusion deficits in 300 μm around the FAZ were significantly increased in patients with DM without DR in full retinal thickness, SCP, and DCP (P < 0.05 for all). When analyzing the perivenular, periarteriolar, and capillary zones, only the perivenular DCP perfusion deficits were significantly increased (5.03 ± 2.92% in DM without DR and 2.73 ± 1.97% in controls, P = 0.014). Conclusions: Macular perfusion deficits in patients with DM without DR were significantly increased in the region nearest the FAZ, mainly at the perivenular deep capillaries. Further research on these early changes may improve our understanding of the capillaries most susceptible to vascular injury and disruption during diabetes. Financial Disclosure(s): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article

Adaptive Optics Reveals Photoreceptor Abnormalities in Diabetic Macular Ischemia

<div><p>Diabetic macular ischemia (DMI) is a phenotype of diabetic retinopathy (DR) associated with chronic hypoxia of retinal tissue. The goal of this prospective observational study was to report evidence of photoreceptor abnormalities using adaptive optics scanning laser ophthalmoscopy (AOSLO) in eyes with DR in the setting of deep capillary plexus (DCP) non-perfusion. Eleven eyes from 11 patients (6 women, age 31–68), diagnosed with DR without macular edema, underwent optical coherence tomography angiography (OCTA) and AOSLO imaging. One patient without OCTA imaging underwent fluorescein angiography to characterize the enlargement of the foveal avascular zone. The parameters studied included photoreceptor heterogeneity packing index (HPi) on AOSLO, as well as DCP non-perfusion and vessel density on OCTA. Using AOSLO, OCTA and spectral domain (SD)-OCT, we observed that photoreceptor abnormalities on AOSLO and SD-OCT were found in eyes with non-perfusion of the DCP on OCTA. All eight eyes with DCP non-flow on OCTA showed photoreceptor abnormalities on AOSLO. Six of the eight eyes also had outer retinal abnormalities on SD-OCT. Three eyes with DR and robust capillary perfusion of the DCP had normal photoreceptors on SD-OCT and AOSLO. Compared to eyes with DR without DCP non-flow, the eight eyes with DCP non-flow had significantly lower HPi (P = 0.013) and parafoveal DCP vessel density (P = 0.016). We found a significant correlation between cone HPi and parafoveal DCP vessel density (r = 0.681, <i>P</i> = 0.030). Using a novel approach with AOSLO and OCTA, this study shows an association between capillary non-perfusion of the DCP and abnormalities in the photoreceptor layer in eyes with DR. This observation is important in confirming the significant contribution of the DCP to oxygen requirements of photoreceptors in DMI, while highlighting the ability of AOSLO to detect subtle photoreceptor changes not always visible on SD-OCT.</p></div

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

Purpose: We 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. Observations: Our 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 importance: We 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. Keywords: Influenza vaccine, Vasculitis, Acute macular neuroretinopathy, AMN, Optical coherence tomography angiography, OCT

Characteristics of Study Participants with Diabetic Retinopathy.

<p>Characteristics of Study Participants with Diabetic Retinopathy.</p

Heterogeneity Packing Index (HPi) of Cones was Significantly Correlated with Deep Capillary Plexus (DCP) Vessel Density.

<p>The Spearman rank test showed a significant correlation between HPi from adaptive optics scanning laser ophthalmoscopy imaging and parafoveal DCP vessel density from optical coherence tomography angiography (r = 0.681, <i>P</i> = 0.030) for the ten eyes with both types of imaging performed.</p

Normal Photoreceptors in an Area of Non-Flow of the Superficial Capillary Plexus (SCP).

<p>Case 1, right eye. (A) Optical coherence tomography angiography (OCTA) of the SCP shows a relatively normal contour of the foveal avascular zone (FAZ) with focal areas of capillary non-flow inferior and superior to the FAZ, including an area imaged by adaptive optics scanning laser ophthalmoscopy (AOSLO) (red circle). (B) OCTA of the deep capillary plexus (DCP) with location of AOSLO montage (green box) and enlarged inset (blue box). DCP shows a normal FAZ, robust capillaries throughout, and a vessel density of 63.46%. (C) <i>En face</i> structural OCT image segmented at the inner segment / outer segment (IS/OS) and the outer segment / retinal pigment epithelium (OS/RPE) junctions is unable to resolve the photoreceptor mosaic. (D) AOSLO montage stitched from 2° x 2° images with location of B-scans (yellow lines) and enlarged inset below (blue box). (E) Enlarged 1° x 1° AOSLO image from montage with heterogeneity packing index of 0.432. Dotted lines indicate location of B-scans. (F) Spectral domain (SD)-OCT from the OCTA device showing robust IS/OS and OS/RPE bands. Green box and blue lines show location of AOSLO montage and enlarged inset, respectively. Green lines indicate the segmentation boundaries for the DCP. White scale bars in A, D and E are 100 μm.</p

Reduced Photoreceptor Heterogeneity Packing Index (HPi) in an Area of Capillary Non-Flow of the Deep Capillary Plexus (DCP).

<p>Case 4, right eye. (A) Optical coherence tomography angiography (OCTA) of the superficial capillary plexus (SCP) shows a relatively normal foveal avascular zone (FAZ), along with distinct foci of capillary non-flow throughout angiogram. (B) OCTA of the DCP with location of adaptive optics scanning laser ophthalmoscopy (AOSLO) montage (green box). DCP reveals an enlarged and irregular FAZ contour and has a vessel density of 55.81%. The red box highlights an area of capillary non-flow and the location of the enlarged AOSLO inset. (C) <i>En face</i> structural OCT image segmented at the inner segment / outer segment (IS/OS) and the outer segment / retinal pigment epithelium (OS/RPE) junctions cannot resolve photoreceptor integrity. (D) AOSLO montage stitched from 2° x 2° images with location of B-scans (yellow lines) and enlarged inset (red box). (E) Enlarged 1° x 1° AOSLO image from montage (HPi = 0.366). Dotted lines indicate location of B-scans. (F) Spectral domain (SD)-OCT from the OCTA device. Green box and red lines show location of AOSLO montage and enlarged inset, respectively. The IS/OS and OS/RPE bands appear normal. Green lines indicate the segmentation boundaries for the DCP. White scale bars in A, D and E are 100 μm.</p

Reduced Photoreceptor Heterogeneity Packing Index (HPi) in an Eye with Capillary Non-Perfusion Contiguous with the Foveal Avascular Zone (FAZ).

<p>Case 7, right eye. (A) Infrared (IR) image with location of adaptive optics scanning laser ophthalmoscopy (AOSLO) montage (green box). (B) Fluorescein angiography (FA) with location of AOSLO montage (green box). (C) Enlarged 1° x 1° AOSLO image from montage (HPi = 0.328). (D) Enlarged FA from B reveals an enlarged and irregular contour of the FAZ with surrounding contiguous areas of capillary non-perfusion. Green box shows location of AOSLO montage in F. Red box shows the location of enlarged AOSLO image (C) in the area of the enlarged FAZ. (E) Spectral-domain optical coherence tomography (SD-OCT) registered to the IR image showing the retinal area covered by the AOSLO montage. B-scan shows focal points where inner segment / outer segment junction is interrupted with decreased intensity of the outer segment / retinal pigment epithelium junction. Red line shows location of enlarged AOSLO image in C. (F) AOSLO montage stitched from 2° x 2° images with location of OCT B-scan (yellow line) and enlarged AOSLO inset (red box).</p