Retinal Vessel Analysis as a Tool to Assess Progression of Pulmonary Arterial Hypertension

Abstract

Purpose : Pulmonary Arterial Hypertension (PAH) is characterized by systemic inflammation, endothelial dysfunction, smooth muscle cell hypertrophy, and vessel obliteration. Typically, after the onset of symptoms a PAH patient undergoes over 10 invasive procedures and requires 2+ years before formal diagnosis. VESsel GENerational Analysis (VESGEN) is a recently released, non-invasive, user-interactive computer software that maps and quantifies the retinal vascular tree using fluorescein angiography (FA) images. We hypothesized that retinal vascular changes, assessed by VESGEN, could predict PAH severity in subjects with PAH.

Methods : In this pilot study, vessel generations of veins and arteries of eyes (n=14) from PAH subjects were determined and grouped into large (G1-3), medium (G4-5), and small (G≥6) vessels by VESGEN analysis.

Results : Among all generation groups, there was an increase of vessel number density (Nv) in veins (8x10^-05 to 1x10^-04 pixel^-2) compared to arteries (5.6x10^-05 to 9.6x10^-05 pixel^-2). Among all eyes, Nv was greater in small veins compared to small arteries. Vessel length density was similar for both veins and arteries (0.00875 ± 0.00089 pixel/pixel² and 0.00965 ± 0.00095 pixel/pixel², respectively). Normal tortuosity, an assessment of vessel curvature, typically ranges from 1.14 to 1.18 pixel/pixel. We observed a higher tortuosity for both veins and arteries in PAH subjects than typically observed in normal retina. Overall, tortuosity in veins and arteries ranged from 1.14 to 1.24 pixel/pixel and 1.17 to 1.25 pixel/pixel, respectively. The arterial tortuosity of large vessels ranged from 1.15 to 1.21 pixel/pixel, medium vessels from 1.13 to 1.28 pixel/pixel and small vessels from 1.20 to 1.25 pixel/pixel.

Conclusions : Although smaller vessels may normally be somewhat more tortuous, such high tortuosity throughout the retinal vascular trees is notable and may derive from intensified plasticity due to hypertension in PAH subjects. This investigation suggests that retinal images may predict PAH severity by changes in tortuosity across all generation groups. Use of FA and VESGEN may facilitate early, non-invasive detection of PAH by careful delineation of changes in retinal vessel tortuosity.

This is a 2020 ARVO Annual Meeting abstract.

 

Tortuosity of veins and arteries (1.24 pixel/pixel and 1.25 pixel/pixel, respectively).