Nailfold Capillaroscopy, Ocular Microvascular Imaging and Clinical Phenotypes in Systemic Sclerosis: Protocol for a Scoping Review

Systemic Sclerosis (SSc) is characterised by early, generalised microvasculopathy that can be visualised non-invasively using nailfold capillaroscopy (NFC). Advanced ocular imaging modalities, particularly optical coherence tomography (OCT), and OCT angiography (OCT-A), now allow non-invasive assessment of the retinal and choroidal microvasculature, revealing subclinical abnormalities in many patients with SSc. However, the link between these changes, clinical disease phenotype, and other connective tissue diseases (CTDs) has not been fully mapped. This review aims to map the literature on ocular microvascular changes in patients with SSc and their relationship to NFC findings and clinical disease phenotype. Evidence will be charted across three streams: (1) paired NFC and ocular imaging findings; (2) NFC and/or ocular imaging findings linked to SSc clinical phenotype; and (3) comparative evidence from prespecified CTDs. The scoping review aims to map the extent and nature of existing evidence; any reported correlations will be considered alongside the methodological heterogeneity, and evidence gaps will be identified to guide future research.