Peripapillary Microvascular Perfusion Contributes to Dysthyroid Optic Neuropathy 

Changes in peripapillary microvascular perfusion may play a role in dysthyroid optic neuropathy (DON), according to a study published in International Ophthalmology. The researchers report that they believe parapapillary choroid microvasculature density increases may be instigating factors in orbital congestion.

Thyroid eye disease (TED) affects the ocular surface and orbital tissues. The clinical activity score (CAS) measures disease activity and guides treatment. In previous studies, optical coherence tomography angiography (OCT-A) has been used to detect deterioration in radial peripapillary capillary (RPC) density in glaucoma or ischemia and parapapillary deep vessel density in glaucomatous optic neuropathy. However, parapapillary deep vessel density has not been studied in TED. Therefore, researchers aimed to evaluate peripapillary microvascular change in the choroid of patients with TED using automated image processing. 

The study participants were divided into 3 groups: group 1 included the controls (n=40), group 2 included inactive TED (ITED, n=22), and group 3 included active TED (ATED, n=19). The mean age of the control group was 43.9, and the TED group was 45.0. Among these, 24 of the 40 in the control group and 21 of the 41 in the TED group were women. 

Annular and hemifield RPC density was significantly lower in the ATED group compared with participants in the control and ITED groups, while parapapillary retinal nerve fiber layer (pRNFL) thickness was significantly higher in the ATED group than controls. There was a notable rise in the density of parapapillary choroid microvasculature (PPCMv) in the ATED group for the entire ring area. 

In the DON subgroup, there was a significant reduction in RPC density, but no changes were observed in pRNFL thickness and PPCMv density. PPCMv density was correlated with pRNFL thickness (r=0.334; P =.002). The RPC density was correlated with the thyroid-stimulating hormone receptor antibody (TSHr AB) level (r<-0.396; P <.001). CAS was positively correlated with parapapillary choroid microvasculature density (r=0.349; P =.001) and pRNFL thickness (r=0.293; P =.008), and negatively correlated with RPC density (r=-0.321; P =.004).

“These results suggest that altered peripapillary microvascular perfusion may contribute to DON,” the researchers explain. “As the level of clinical activity increases, so does the change in the peripapillary parameters.”

Study limitations include the small number of non-DON and DON subgroups. Additionally, no longitudinal RPC density and PPCMv density data were available. Smoking may have affected the results of OCT-A.

This article originally appeared on Ophthalmology Advisor