Phase-Resolved Doppler Optical Coherence Tomographic Features in Retinal Angiomatous Proliferation

Intraretinal Cysts as a Manifestation of Retinal Angiomatous Proliferation in Optical Coherence Tomography Angiography

Background and Objectives: Intraretinal cysts are common pathology observed inspectral domain optical coherence tomography (SDOCT) in patients with neovascular form of age-related macular degeneration (AMD). The aim of the study was to determine if the presence of intraretinal cysts is positively correlated with diagnosis of retinal angiomatous proliferation (RAP) in optical coherence tomography angiography (OCTA). Material and Methods: A total of 21 eyes with intraretinal cysts in SDOCT exam (Group1) and 21 eyes with subretinal fluid(Group 2) were enrolled into the study. In each eye, the presence of intraretinal neovascularization (IRN) and chorioretinal anastomosis (CRA) was evaluated in OCTA by two experienced graders. Results: IRN was observed in 20 eyes (95.2%) from Group 1 and 5 eyes (23.8%) from Group 2. Features of CRA were found in 18 eyes (80.95%) and 16 eyes (76.2%) respectively for Group 1 and 2. Patients with cysts are 50 (95% CI: 5.43−460.52) times more likely to have IRN (p < 0.001). Conclusions: The presence of intraretinal cysts on SDOCT retinal sections in eyes with neovascular AMD corresponds to the presence of IRN on OCTA examination. The results indicate that the absence of a cyst does not exclude the presence of IRN and CRA which can be identified on OCTA.

Detailed optical coherence tomography angiographic short-term response of type 3 neovascularization to combined treatment with photodynamic therapy and intravitreal bevacizumab

PURPOSE

To explore the short-term vascular and structural changes of type 3 neovascularization using optical coherence tomography angiography (OCT-A) when treated with a combination of photodynamic therapy (PDT) and intravitreal bevacizumab (IVB), and to evaluate the course of different sequences of the combined therapies.

METHODS

Thirty eyes of 29 treatment-naïve patients with a type 3 neovascularization were included in this prospective observational cohort study. They were all treated with PDT and IVB 2 weeks apart, starting either with PDT (PDT-first group) or IVB (IVB-first group). Optical coherence tomography angiography (OCT-A) imaging was performed at week 0, 2, 4 and 18, and best corrected visual acuity (BCVA) at week 0 and 18. Vascular, structural and functional features were graded and analysed over time.

RESULTS

In all patients, at all follow-up visits, vascular and structural features were significantly more often decreased or resolved than unchanged or increased. Best corrected visual acuity (BCVA) significantly improved at 18 weeks. Vascular, structural and functional outcomes were all slightly better in the PDT-first group compared to the IVB-first group, although not statistically significant.

CONCLUSION

Combined treatment of PDT and IVB is effective in short-term for type 3 neovascularization based on vascular and structural features. Initial treatment with PDT tended to be more effective than with IVB.

Intra- and Intergrader Agreement for Detection of OCT Angiographic Characteristics Associated With Type 3 Neovascularization

Purpose

To examine the intra- and intergrader agreement on morphologic characteristics of type 3 neovascularization on optical coherence tomography angiography (OCT-A).

Methods

OCT-A images of 22 eyes from 21 patients with a new-onset, treatment-naive type 3 neovascularization were included in this cross-sectional retrospective agreement study. Each image was graded three times by two independent medical retina specialists to assess intra- and intergrader agreement. The graders scored the presence or absence of the following vascular and structural features: intraretinal neovascularization (IRN), subretinal neovascularization, sub-retinal pigment epithelium (RPE) neovascularization (SRPEN), retinal choroidal anastomosis (RCA), intraretinal cysts, subretinal fluid, and pigment epithelial detachment. Agreement was analyzed for each feature using Gwet's AC₁, к statistics, and percentage of agreement.

Results

The best agreement (AC₁) was found for intraretinal neovascularization (within_grader1: 0.94; within_grader2: 0.93 and between: 1.00) and intraretinal cysts (within_grader1, 1.00; within_grader2, 0.97 and between, 1.00). The poorest intragrader agreements were observed for SRPEN (within_grader1, 0.54 and within_grader2, 0.36) and RCA (within_grader1, 0.45 and within_grader2, 0.52), and the poorest intergrader agreement was found for SRPEN, RCA, and pigment epithelial detachment (0.18, 0.37, and 0.15, respectively).

Conclusions

Although the agreement values were high for intraretinal features, considerable grader variability was found for the vascular and structural features in the deeper retina or under the RPE. Clinicians should be careful to base therapeutic decisions on qualitative OCT-A assessment, because even well-trained specialists show a considerable grader variation in their subjective evaluation.

Translational Relevance

The clinical value of OCT-A imaging largely depends on the agreement of subjective evaluations by ophthalmologists.

Compressed sensing-enabled phase-sensitive swept-source optical coherence tomography

Here we present a novel phase-sensitive swept-source optical coherence tomography (PhS-SS-OCT) system. The simultaneously recorded calibration signal, which is commonly used in SS-OCT to stabilize the phase, is randomly sub-sampled during the acquisition, and it is later reconstructed based on the Compressed Sensing (CS) theory. We first mathematically investigated the method, and verified it through computer simulations. We then conducted a vibrational frequency test and a flow velocity measurement in phantoms to demonstrate the system's capability of handling phase-sensitive tasks. The proposed scheme shows excellent phase stability with greatly discounted data bandwidth compared with conventional procedures. We further showcased the usefulness of the system in biological samples by detecting the blood flow in ex vivo swine left marginal artery. The proposed system is compatible with most of the existing SS-OCT systems and could be a preferred solution for future high-speed phase-sensitive applications.

Treatment Effects in Retinal Angiomatous Proliferation Imaged with OCT Angiography

PURPOSE

This prospective case series is aimed at exploring optical coherence tomographic angiography (OCT-A) as a treatment monitoring tool in patients treated for retinal angiomatous proliferation (RAP).

METHODS

Twelve treatment-naïve RAP patients were included, with a median age of 79 years (range 65-90). Patients were imaged with an experimental 1,040-nm swept-source phase-resolved OCT-A instrument before and after treatment. Treatment consisted of either intravitreal bevacizumab or triamcinolone injections with or without photodynamic therapy (PDT). Abnormal blood flow after treatment was graded as increased, unchanged, decreased, or resolved.

RESULTS

OCT-A images before and after treatment could be obtained in 9 patients. The median follow-up period was 10 weeks (range 5-19). After various treatments, the RAP lesion resolved in 7 patients, in 1 patient the OCT-A depicted decreased flow in the lesion, and 1 patient showed unchanged abnormal blood flow. Monotherapy with intravitreal bevacizumab injections resolved RAP in 1 out of 2 patients. Combined therapy of bevacizumab with PDT resolved RAP in 6 out of 7 patients.

CONCLUSIONS

OCT-A visualized resolution of abnormal blood flow in 7 out of 9 RAP patients after various short-term treatment sequences. OCT-A may become an important noninvasive monitoring tool for optimizing treatment strategies in RAP patients.

The role of OCT-A in retinal disease management

Optical coherence tomography angiography (OCT-A) is a non-invasive, non-dye-based imaging modality that has the potential to enhance our understanding of retinal diseases. While this rapidly advancing imaging modality offers great potential, there is a need for community-wide understanding of the range of technologies and methods for interpreting the images, as well as a need to enhance understanding of images from disease-free eyes for reference when screening for retinal diseases. Importantly, clinical trials have been designed without OCT-A-based endpoints; therefore, caution is required when making treatment decisions based on OCT-A imaging alone. With this in mind, a full understanding of the advantages and limitations of OCT-A will be vital for effective development of the technique within the field of ophthalmology. On behalf of the Vision Academy Steering Committee (sponsored by Bayer), this publication summarizes the views of the authors on the current use of OCT-A imaging and explores its potential for future applications in research and clinical practice.

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

Objective

To evaluate the projection-resolved (PR) optical coherence tomography angiography (OCTA) algorithm in detecting plexus-specific vascular abnormalities in retinal pathologies.

Design

Cross-sectional observational clinical study.

Participants

Patients diagnosed with retinal vascular diseases and healthy volunteers.

Methods

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.

Main Outcome Measures

Qualitative observation of vascular abnormalities on both cross-sectional and en face PR-OCTA images.

Results

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.

Conclusions

Application of PR-OCTA promises to improve sensitive, accurate evaluation of individual vascular plexuses in multiple retinal diseases.

TYPE 3 NEOVASCULARIZATION IMAGED WITH CROSS-SECTIONAL AND EN FACE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

PURPOSE

To study the cross-sectional and en face optical coherence tomography angiography (OCTA) findings in Type 3 neovascularization (NV).

METHODS

Optical coherence tomography angiography imaging of 27 eyes of 23 patients with Type 3 NV was analyzed with 9 eyes having consecutive follow-up OCTA studies.

RESULTS

Type 3 NV appeared as a linear high-flow structure on cross-sectional OCTA corresponding to a high-flow tuft of vessels seen on en face OCTA. Cross-sectional OCTA seemed to enable the distinction between vascular and nonvascular intraretinal hyperreflective foci. Two patterns of flow were observed; Pattern 1 (11%): a flow signal confined to the neurosensory retina and Pattern 2 (74%): a flow signal extending through the retinal pigment epithelium. No definitive retinal-choroidal anastomosis was observed; however, projection artifacts confounded the interpretation of deeper structures. An increase in the intensity of the high-flow tuft was seen during the progression or recurrence of Type 3 NV. Intravitreal anti-vascular endothelial growth factor therapy caused a reduction in the intensity of the high-flow tuft which was not sustained.

CONCLUSION

Compared with conventional imaging, OCTA may improve detection and delineation of vascular changes occurring in Type 3 NV. Cross-sectional and en face OCTA may prove useful in studying the pathogenesis and guiding the management of these lesions.