Thyroid-Associated Peripapillary Vascular Remodelling – A Novel Area for Research? [Letter]

We read the study on changes in the capillary and non-capillary peripapillary perfusion (NCPP) in inactive thyroid eye disease (TED) without dysthyroid optic neuropathy (DON) using ocular coherence angiography (OCTA) for the radial peripapillary capillary (RPC) layer scans with great interest. he authors highlighted the importance of a separate assessment of retinal capillary and non-capillary (arteriole and venule) blood vessels in TED, citing structural differences in the two classes of blood vessels. Unlike the capillaries, the non-capillary vessels are larger in diameter, and the tunica media is composed of smooth muscle cells. These smooth muscle cells are hypothesized to proliferate in response to the upregulation of transforming growth factor (TGF)- in TED orbits, resulting in vessel wall thickening and decreased perfused luminal area. A significant reduction was noted in the NCPP densities in all eight cases (15.4 2.9%) as compared to the healthy controls (21.53.1%). However, two of the study subjects with the lowest NCPP densities 11.6% and 10.6%, had additional factors likely to affect the vascular perfusion, being on progesterone therapy and an active smoker, respectively.