Amblyopic Eyes Show Reduced Retinal Vessel Density Compared to Fellow Eyes Using Widefield Swept-Source Optical Coherence Tomography Angiography

Purpose: Amblyopia has traditionally been considered a purely functional disorder without an organic correlate. Recent optical coherence tomography angiography (OCTA) studies, however, revealed alterations in the central retinal vasculature of amblyopic eyes. This prospective, monocentric study is the first, to our knowledge, to employ widefield swept-source OCTA (WF-SS-OCTA) for a quantitative assessment of the retinal and choroidal vasculature extending to the periphery, comparing amblyopic eyes with healthy fellow eyes. Methods: Patients with unilateral amblyopia were recruited at Münster University Hospital and underwent WF-SS-OCTA imaging. The superficial capillary plexus (SCP) and choroid were analyzed using AngioTool software. Results: A total of 102 eyes from 51 patients were included. In amblyopic eyes, the SCP demonstrated significantly lower vessel pixel density (VPD) (P = 0.01), fewer junctions (P = 0.01), shorter vessel length (total and average, both P < 0.01), and increased lacunarity (P < 0.01) compared to fellow eyes, whereas the number of end points did not differ significantly (P = 0.10). Subgroup analysis showed that moderate amblyopia was associated with significantly lower VPD, fewer junctions, and shorter total vessel lengths compared to mild amblyopia, with no significant differences in end points or lacunarity. No significant differences were observed in choroidal vascular parameters (all P > 0.46). Conclusions: These findings support an organic correlate of amblyopia, characterized by a less dense superficial retinal vascular network, possibly reflecting postnatal regression or impaired retinal vascular development due to inadequate visual stimulation in early childhood. Translational Relevance: WF-SS-OCTA may provide an objective imaging biomarker for amblyopia severity.