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Introduction The presence of mega capillaries at nailfold video capillaroscopy is a cardinal sign for the very early diagnosis of SSc (VEDOSS) and supports active vasculopathy as a very early sign of disease.Recent multiomics and functional studies from forearm VEDOSS skin biopsies have indicated that despite the absence of skin thickening, the immunological and profibrotic biological culprits of SSc are already detectable in the very early stages of SSc.Dynamic OCT is a non invasive, validated imaging technique able to detect and measure skin capillaries and already shown of value in SSc.Here we aimed to analyse the capillary morphology and density in VEDOSS patients to investigate the presence of vasculpathy beyond the nailfold in this very early stage of disease.Material and Methods In this cross-sectional study, dynamic OCT imaging of the index fingers, hands, and forearms was performed in three groups: (i) healthy controls, (ii) patients fulfilling VEDOSS criteria and (iii) SSc patients with late disease and mRSS=0 on hands and forearms to avoid any possible bias led by skin thickening.Quantitative OCT parameters, including vessel density, plexus depth, and vessel diameter, were measured and compared across groups using appropriate statistical tests.Results Sixty-seven participants were included: 16 healthy controls, 32 VEDOSS patients and 19 late SSc patients (17 lcSSc and 2 dcSSc) with mRSS=0.Age distribution were comparable between VEDOSS and HC (49.4±11.7 vs 47.7±13.7) whereas patients wiht late SSs were older, as expected (59.8±13). Mean capillary diameter was significantly higher in VEDOSS than HC or late SSc (41.21±13.13 vs 28.86±12.92 and 30.31±9.54; 47.17±16.13 vs 27.19±6.12 and 35.24±10.26; 43.22±15.19 vs 25.50±7.35 and 32.71±17.04, p<0.05 for all) resembling the mega capillaries dictating the active pattern at nailfold videocapillaroscopy.Mean vessel density was also in average 5 fold higher in fingers and hands (6.37±4.83 vs 1.69±1.04 and 2.35±2.26; 6.9±4.84 vs 1.29±0.87 and 2.62±1.75, p>0.001 for both) and 2 to 3 fold higher in forearms (3.41±2.72 vs 0.82±1.35 and 1.67±1.94, p<0.001).The capillary plexus was deeper in VEDOSS compared to HC or late SSc, suggesting a thicker papillary dermis (305±56.74 vs 206±65.87 and 179±75.36; 316±78.19 vs 236±58.19 and 203±56.45; 299.31±75.68 vs 228±36.71 and 205±48.51, p<0.001 for all).Conclusions Dynamic OCT of VEDOSS skin reveals signs of vasculopathy comparable to enlarged capillaries and increased superficial dermis thickness.Our data support the notion of a biologically active skin disease with evidence of vasculopathy in the very early stages of SSc and support the use of D-OCT in the assessment of vascular disease activity in SSc.Abstract P.066 Figure 1Representative 3D vascular imaging in the three groupsAbstract P.066 Figure 2Comparison of mean vessel density among healthy controls, SSe with mRSS-0, and VEDOSSAbstract P.066 Figure 3Comparison of mean plexus depth among healthy controls, SSc with mRSS-0, and VEDOSSAbstract P.066 Figure 4Comparison of mean vessel diameter among healthy controls, SSe with mRSS=0, and VEDOSSAbstract P.066 Table 1Quantitative OCT metrics by asessment site in healthy controls, SSc with mRSS-0, and VEDOSS