Choriocapillaris in AMD: A Systematic Review of OCTA-Based Assessments and Challenges in Standardization.
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TOPIC: This systematic review evaluates the methodologies employed for assessing the choriocapillaris (CC) in age-related macular degeneration (AMD) using optical coherence tomography angiography (OCTA). It focuses on identifying methodological heterogeneity in imaging and analysis protocols and its implications for clinical and research applications. CLINICAL RELEVANCE: AMD is a leading cause of vision loss, and assessing CC perfusion provides critical insights into its pathophysiology. OCTA has emerged as a non-invasive imaging technique offering high-resolution visualization of the CC. However, variability in methodologies has hindered the standardization of CC assessments. Establishing consistent practices is essential for improving clinical and research outcomes in AMD management. DESIGN: Systematic review. METHODS: Studies included in this review were selected based on eligibility criteria defined by the PICOS framework. Participants included patients with early, intermediate, and late AMD. Interventions involved the use of OCTA for CC assessment, with no restrictions on device type or scan parameters. Comprehensive searches of MEDLINE, Web of Science Core Collection, and the Cochrane Library were conducted up to November 30, 2024. Data extractions and narrative synthesis focused on device types, scan protocols, segmentation techniques, compensation strategies, and quantitative metrics. RESULTS: A total of 102 studies, encompassing 4,047 AMD patients and 4,415 eyes, were analyzed. Fifty-two studies employed spectral-domain OCTA, and 49 used swept-source OCTA, with significant heterogeneity in segmentation boundaries and slab thickness (4.4 µm to 30 µm). Only 32 studies used compensation strategies to address signal attenuation under drusen. Quantitative metrics varied widely, with CC flow deficit percentage (CCFD%) being the most common. However, inconsistencies in thresholding methods and lack of standardized Phansalkar radius reporting limited comparability. The review highlights gaps in reporting segmentation boundaries and compensation techniques, which impact the ability to assess the reliability of findings. CONCLUSION: This review underscores substantial variability in methodologies for CC assessment in AMD, highlighting the urgent need for standardized imaging protocols and analytical approaches. Despite advances in OCTA technology, inconsistencies in segmentation, thresholding, and compensation strategies challenge data reliability and reproducibility. Future research should prioritize methodological standardization to enhance comparability and clinical applicability.
