Optical coherence tomography angiography detects retinal microvascular changes in giant cell arteritis: the potential protective role of aortitis.

OBJECTIVES

To evaluate the diagnostic utility of optical coherence tomography angiography (OCTA)-derived biomarkers in patients with giant cell arteritis (GCA) and to advance the pathophysiological understanding of disease-related microvascular alterations and their association with vascular manifestation.

METHODS

Newly diagnosed, untreated GCA patients and healthy controls were assessed using OCTA of the optic nerve head (ONH). Skeletonised and binarised vessel densities were quantified in retinal vascular plexus and in the choriocapillaris in concentric rings around the ONH (0.5/1.0 mm diameter). Associations with clinical data, vascular ultrasound including Outcome Measures in Rheumatology Giant Cell Arteritis Ultrasonography Score (OGUS) and large-vessel involvement were evaluated using correlation and multivariable regression analyses.

RESULTS

A total of 60 GCA patients and 69 healthy controls were prospectively enrolled. Reduced vessel density in the outer ring (1 mm) of the superficial retinal plexus was the strongest OCTA-derived discriminator of GCA (r=0.28, p=0.001), independent of visual symptoms. Multivariable regression identified lower superficial plexus density as significantly associated with GCA (β=-0.22, p=0.015). Calculated OGUS was positively associated with OCTA alterations (ρ=0.28, p=0.03), while aortic involvement was inversely associated (ρ=-0.32, p=0.02). Age was the only independent predictor of visual symptoms (β=0.173, p=0.013).

CONCLUSIONS

Our study reveals microvascular alterations in GCA, even in the absence of visual symptoms. Vessel density reduction in the superficial peripapillary plexus may serve as an early biomarker of retinal hypoperfusion. The inverse association with aortic involvement supports the concept of distinct immunophenotypes in GCA.