Subclinical retinal angiopathy associated with hereditary transthyretin amyloidosis - assessed with optical coherence tomography angiography.

Background: Retinal angiopathy is a known ocular manifestation of hereditary transthyretin amyloidosis (ATTRv). Optical coherence tomography angiography (OCT-A) is a recent noninvasive imaging technique, used in other retinal vascular diseases. Our purpose was to analyse subclinical changes in retinal vessels, with OCT-A, in patients with ATTRv amyloidosis.

Methods: Observational cross-sectional study in in the cohort of patients with genetic diagnosis of ATTRv. Patients were included if they had just one eye with scalloped iris (the other eye without scalloped iris), postulating eyes were at different stages, in the same patient. Patients were excluded if they had other manifestations of ocular ATTRv amyloidosis, namely clinical retinal angiopathy and/or vitreous opacities. The group of eyes with scalloped iris were compared with eyes without scalloped iris, using paired tests. Values are shown as Δ = mean difference between groups;  = , = Cohen's for effect size measurement.

Results: Twenty-four patients (24 eyes in each group) were included. Mean age was 46.5 ± 5.0 years. Eyes with scalloped iris showed attenuated retinal vascular network: larger foveal avascular zone (FAZ) area (Δ = +0.02 mm,  = 0.002,  = 0.70); decreased foveal vascular density (Δ = -3.57%,  = 0.001,  = -0.75); superficial (Δ = -1.50%,  = 0.049, = -0.43) and deep (Δ = -2.53%,  = 0.023, = -0.50) plexus vascular density. Acircularity index was superior in scalloped iris eyes (Δ = 0.04,  = 0.004, = -0.65), representing an abnormal FAZ morphology.

Conclusion: Scalloped iris in ATTRv eyes are associated with a more advanced subclinical retinal angiopathy, than eyes without scalloped iris. Our results identify for the first time and , early changes in retinal vessels in ATTRv amyloidosis. Henceforward, OCT-A may play a role in the evaluation of ATTRv patients oculopathy and the effectiveness of future eye targeting treatments.