Longitudinal Microvascular Changes in Vascular Paralytic Strabismus: A Prospective Optical Coherence Tomography...

To evaluate dynamic intraocular microvascular changes in vascular paralytic strabismus using optical coherence tomography angiography (OCTA) and choroidal vascularity index (CVI), and to assess their reversibility after clinical recovery. In this prospective study, 31 patients with acute-onset vascular paralytic strabismus involving the third, fourth, or sixth cranial nerve were enrolled. OCTA and enhanced depth imaging (EDI)-OCT were performed during the paralytic phase and after full recovery. Parameters included vessel density (VD) in the superficial (SCP) and deep capillary plexuses (DCP), foveal avascular zone (FAZ), choriocapillaris flow, CVI and peripapillary vessel density (ppVD). Inter-eye and inter-phase differences were analysed. Statistical analysis was performed using generalised estimating equations (GEE) to account for within-subject correlations between eyes. During the paralysis phase, the affected eyes showed significantly reduced VD in the SCP across all macular regions, while changes in the DCP were limited to the fovea (p < .001). The FAZ area was larger (p = .012), and CVI was lower (p < .001) in the affected eye. After clinical recovery, SCP VD, choriocapillaris flow, and CVI in the previously affected eyes increased significantly, while FAZ and non-flow area decreased (p < .001 for both). Intradisc ppVD also improved (p = .048). Retinal and choroidal thickness remained stable. Vascular paralytic strabismus causes reversible ischaemic alterations, primarily in the macular SCP and choroid. These findings support a functional vascular disturbance rather than structural damage. This is the first study to evaluate the CVI in this condition, highlighting the utility of OCTA and EDI-OCT as noninvasive tools for monitoring dynamic ocular perfusion alterations.