Recent Advances in Imaging Polypoidal Choroidal Vasculopathy with Swept-Source Optical Coherence Tomography Angiography

The gold standard for polypoidal choroidal vasculopathy (PCV) diagnosis is indocyanine green angiography (ICGA), but optical coherence tomography angiography (OCTA) has shown promise for PCV imaging in recent years. However, earlier generations of OCTA technology lacked the diagnostic efficacy to replace ICGA. Swept-source optical coherence tomography angiography (SS-OCTA), the latest generation of OCTA technology, has significantly improved penetrating ability, scanning speed, scanning range, and overall image quality compared with earlier generations of OCTA. SS-OCTA reveals a "tangled vasculature" pattern of polypoidal lesions (PLs), providing evidence that they are neovascular rather than aneurysmal structures. New choroidal biomarkers, such as the choriocapillaris flow void (FV), have been identified to explain the development of PCV lesions. Although no direct comparison between SS-OCTA and previous OCTA generations in terms of diagnostic capability has been performed, SS-OCTA has shown several advantages in differential diagnosis and monitoring early reactivation for PCV. These improvements make SS-OCTA a valuable tool for PCV diagnosis and follow-up, and it may become more important for this disease in the future. This review summarized recent advances in PCV morphology and structure, as well as the possible pathogenesis based on SS-OCTA findings. The value of SS-OCTA for PCV management is discussed, along with remaining issues, to provide an updated understanding of PCV and OCTA-guided management.

New Concepts for the Diagnosis of Polypoidal Choroidal Vasculopathy

Polypoidal choroidal vasculopathy (PCV) is a subtype of neovascular age-related macular degeneration (nAMD) that is characterized by a branching neovascular network and polypoidal lesions. It is important to differentiate PCV from typical nAMD as there are differences in treatment response between subtypes. Indocyanine green angiography (ICGA) is the gold standard for diagnosing PCV; however, ICGA is an invasive detection method and impractical for extensive use for regular long-term monitoring. In addition, access to ICGA may be limited in some settings. The purpose of this review is to summarize the utilization of multimodal imaging modalities (color fundus photography, optical coherence tomography (OCT), OCT angiography (OCTA), and fundus autofluorescence (FAF)) in differentiating PCV from typical nAMD and predicting disease activity and prognosis. In particular, OCT shows tremendous potential in diagnosing PCV. Characteristics such as subretinal pigment epithelium (RPE) ring-like lesion, en face OCT-complex RPE elevation, and sharp-peaked pigment epithelial detachment provide high sensitivity and specificity for differentiating PCV from nAMD. With the use of more practical, non-ICGA imaging modalities, the diagnosis of PCV can be more easily made and treatment tailored as necessary for optimal outcomes.

Optical coherence tomography angiography analysis of aneurismal type 1 neovascularization in a cohort of white patients

INTRODUCTION

To evaluate the detection rate of aneurysmal type 1 neovascularization (AT1) in Caucasian patients using optical coherence tomography angiography (OCTA) and to describe OCTA characteristics of AT1 in a cohort of white patients.

METHODS

We conducted an observational retrospective study in 44 eyes of 43 patients with AT1. All patients underwent a complete ophthalmologic examination, including fundus imaging, indocyanine green angiography, optical coherence tomography, and OCTA. Branching vascular network (BVN) and polyp detection rates by OCTA were evaluated. Furthermore, we described BVN and polyp morphologies on en face OCTA and flow of polyps on B-scan OCTA.

RESULTS

En face OCTA revealed BVN in 84.09% of cases and polypoidal lesions in 86.36% of cases. B-scan OCTA showed BVN and polyps in 95.45% and 93.18% of the patients, respectively. "Trunk" BVNs (51.35%) and "ring" polyps (47.37%) were the most frequent morphologies observed in our cohort, and "patchy hyperflow" (80.49%) signal was the most common visualized in our patients. Regarding OCT parameters, CT under polyps was higher in patients with positive detection of polyps on B-scan OCTA.

CONCLUSION

OCTA is a possible diagnosis tool in Caucasian patients with AT1. To the best of our knowledge, this is the largest study performed in Caucasian patients regarding OCTA diagnostic abilities and features.

Differentiating Exudative Macular Degeneration and Polypoidal Choroidal Vasculopathy Using OCT B-Scan

PURPOSE

Although polypoidal choroidal vasculopathy (PCV) is best diagnosed with indocyanine green angiography (ICGA), ICGA is often unavailable or not ordered. OCT is widely available, and OCT B-scan can visualize polypoidal lesions diagnostic of PCV as inverted U-shaped elevations of the retinal pigment epithelium (RPE) with heterogeneous reflectivity and sometimes ring-shaped lesions within the polypoidal lesion. This study aims to differentiate findings between eyes diagnosed with PCV or typical exudative age-related macular degeneration (AMD) using ICGA and then compares findings noted on the OCT B-scan line scan in each group.

DESIGN

Retrospective, chart review.

METHODS

Clinical features of eyes with PCV and typical exudative AMD were compared by using ICGA. Eyes with PCV were evaluated for inverted U-shaped polypoidal lesions, which are the main differentiating finding of PCV from typical exudative AMD. Data collected included presence of subretinal fluid (SRF), macular edema or intraretinal edema, subretinal hyperreflective material (SHRM), and retinal pigment epithelial detachment (RPED). These findings were evaluated in 2 parts: baseline and after 6 to 9 months of antiangiogenic therapy. Additionally, analysis was performed for the presence of polypoidal lesions before and after treatment.

MAIN OUTCOME MEASURES

Presence of inverted U-shaped lesions on OCT B-scan following treatment.

RESULTS

A total of 112 eyes of 106 patients were included. A total of 69 eyes were diagnosed with PCV, and 43 eyes were diagnosed with typical exudative AMD. Compared with AMD eyes, PCV eyes had an increased prevalence of SRF at baseline and after 6 to 9 months of treatment, but the prevalence of macular edema, SHRM, and RPED was similar at baseline and at 6 to 9 months after treatment. In PCV eyes, the presence of visible polypoidal lesions decreased from 56.5% to 24.6% after treatment.

CONCLUSIONS

If PCV is suspected in an anti-vascular endothelial growth factor (VEGF)-resistant case of exudative AMD, in the absence of ICGA availability, it is important to look at the baseline OCT B-scan before therapy for evidence of polypoidal lesions. The characteristic inverted U-shaped elevation was present in more than half of PCV eyes on OCT B-scan at baseline but disappeared after antiangiogenic therapy in 56.4% of cases in which this was initially identified. Subretinal fluid was more prevalent in PCV eyes than non-PCV AMD eyes.

A Comparison Study of Polypoidal Choroidal Vasculopathy Imaged with Indocyanine Green Angiography and Swept-Source Optical Coherence Tomography Angiography

PURPOSE

Indocyanine green angiography (ICGA) was compared with swept-source optical coherence tomography angiography (SS-OCTA) for the detection of polypoidal choroidal vasculopathy (PCV).

DESIGN

Retrospective, cross-sectional.

METHODS

Patients with treatment-naïve PCV based on ICGA imaging underwent same-day SS-OCTA imaging at Kyung Hee University Medical Center between April 2017 and November 2018. ICGA and SS-OCTA images were graded independently. SS-OCTA images were graded using both flow and structural information. Images were graded for the number of polypoidal lesions and the total lesion area, which included both the polypoidal lesions and the branching vascular networks (BVNs).

RESULTS

A total of 31 eyes from 30 patients were enrolled. Polypoidal lesions were identified in all eyes using both modalities, and there was agreement on the number of polypoidal lesions in 17 eyes (55%). In 12 eyes (39%), SS-OCTA graders identified a greater number of polypoidal lesions, and in 2 eyes (6%) ICGA graders identified more lesions. There was no significant difference in the lesion area measurements (standard deviation = 1.09, P = .08). The lesion with the largest difference in area measurements resulted from focal areas of atrophy, misdiagnosed as polypoidal lesions on ICGA, and a low-lying serous retinal pigment epithelial detachment erroneously identified as part of the BVN by ICGA graders. SS-OCTA imaging correctly diagnosed the focal areas of atrophy and the serous retinal pigment epitheial detachment.

CONCLUSIONS

SS-OCTA imaging was comparable to ICGA for the diagnosis of treatment-naïve PCV. However, SS-OCTA might be better than ICGA in correctly identifying both polypoidal lesions and BVNs in treatment-naïve PCV.

Detection Rate and Diagnostic Value of Optical Coherence Tomography Angiography in the Diagnosis of Polypoidal Choroidal Vasculopathy: A Systematic Review and Meta-Analysis

Purpose

This study aimed to evaluate the detection rate of polyps and branching vascular networks (BVNs) in polypoidal choroidal vasculopathy (PCV) by optical coherence tomography angiography (OCTA) and assess the sensitivity and specificity of OCTA in differentiating PCV from wet age-related macular degeneration (wAMD).

Materials and Methods

We searched PubMed, EMBASE, Cochrane Library, and other sources. The detection rates of polyps and BVNs in observational studies and the sensitivity and specificity of PCV diagnosis from wAMD in diagnostic studies were extracted.

Results

Twenty studies (573 eyes) were eligible. The combined detection rate of OCTA in PCV polyp lesion diagnosis was 0.67 (95% CI: 0.55–0.79), while that of BVNs was 0.86 (95% CI: 0.81–0.91). The detection rate of polyps was compared with that of BVNs in the same study, and the combined relative risk was 0.82 (95% CI: 0.72–0.92). The combined sensitivity of PCV diagnosis in wAMD patients using OCTA was 0.77 (95% CI: 0.55–0.90), combined specificity 0.84 (95% CI: 0.60–0.95), and area under the SROC curve 0.87 (95% CI: 0.84–0.90).

Conclusion

OCTA has a high PCV polyp and BVN detection rate, and the detection rate of BVNs is higher than that of the polyp. OCTA has acceptable sensitivity and specificity for diagnosing PCV from wAMD. Thus, OCTA may be helpful for clinical diagnosis of PCV.

Evaluating diurnal changes in choroidal sublayer perfusion using optical coherence tomography angiography

PURPOSE

To investigate diurnal changes of choroidal sublayer perfusion in normal eyes and to identify influencing factors using optical coherence tomography angiography (OCTA).

METHODS

A prospective study was conducted on healthy volunteers, each of whom underwent repeated measurements of subfoveal choroidal thickness (SFCT) via enhanced depth imaging (EDI) optical coherence tomography (OCT) as well as perfusion of choroidal vascular sublayers using OCTA at 7 a.m., 12 p.m., 4 p.m. and 8 p.m. Possible interactions between diurnal variations and other factors, such as mean arterial pressure (MAP), gender and age, were evaluated.

RESULTS

A total of 22 eyes from 22 participants were analysed. Mean age of participants was 56 years. A significant pattern of diurnal variation was observed for SFCT (p < 0.001) as well as perfusion of Sattler's layer (SLP; p = 0.009) and Haller's layer (HLP; p = 0.003). SFCT demonstrated a linear decrease, being thicker in the morning (348 μm) and thinner in the evening (310 μm). Both, SLP and HLP showed a quadratic relation to time of day, increasing from morning (64% and 76%) to afternoon (66% and 77%), before decreasing again in the evening (64% and 76%). HLP changes were significantly associated with fluctuations of MAP (B = 0.0007; CI 0.0001-0.0014; p = 0.047). No significant differences with regard to gender were detectable. However, older participants (≥60 years) had fewer diurnal changes (p = 0.042).

CONCLUSION

Optical coherence tomography angiography-based analysis of choroidal sublayer perfusion demonstrated significant diurnal variations. Therefore, it is important to account for time of day, when comparing longitudinal OCTA data.

Anti-Vascular Endothelial Growth Factor Resistance in Exudative Macular Degeneration and Polypoidal Choroidal Vasculopathy

PURPOSE

To evaluate the prevalence of polypoidal choroidal vasculopathy (PCV) in different ethnic populations and to determine the prevalence of PCV in eyes with exudative age-related macular degeneration (AMD) that is sensitive and resistant to anti-vascular endothelial growth factor (VEGF) therapy.

DESIGN

Retrospective chart review.

PARTICIPANTS

Two hundred fifty-three eyes of 221 patients with exudative AMD.

METHODS

Baseline data were collected on all eyes diagnosed with exudative AMD, which included ethnic data. Polypoidal choroidal vasculopathy was diagnosed using indocyanine green angiography (ICGA) with the scanning laser ophthalmoscope. Exudative AMD eyes were separated into 2 groups: anti-VEGF-resistant eyes with persistent subretinal fluid, subretinal hemorrhage, or macular edema after 4 anti-VEGF injections and anti-VEGF-sensitive eyes defined as eyes without residual disease activity. The prevalence of PCV was determined in each group based on ICGA.

MAIN OUTCOME MEASURES

Prevalence of PCV in exudative AMD, and in different ethnic populations, and prevalence of anti-VEGF resistance in eyes with and without PCV.

RESULTS

Exudative AMD was diagnosed in 253 eyes of 221 patients. Polypoidal choroidal vasculopathy was noted to have a prevalence of 45.1% (114/253 eyes) in the overall population. Polypoidal choroidal vasculopathy was noted in 51.6% (81/157) of eyes with wet AMD in Asians, 31.9% (23/72 eyes) of eyes with wet AMD in white persons, and 28.6% (4/14 eyes) in a small group of Pacific Islanders. Polypoidal choroidal vasculopathy was diagnosed in 50% (60/120 eyes) of eyes in the anti-VEGF-resistant group, which is more prevalent than the 30.2% (29/96 eyes) in the anti-VEGF-sensitive group (P < 0.001).

CONCLUSIONS

Polypoidal choroidal vasculopathy is more prevalent in Asian patients with exudative AMD, but is more prevalent than generally recognized in white patients. Polypoidal choroidal vasculopathy is more prevalent in anti-VEGF-resistant eyes in both white and Asian patients, which could help to predict therapeutic response.