Microvascular Changes May Indicate Dysthyroid Optic Neuropathy Development

Patients with equivocal dysthyroid optic neuropathy (EDON) exhibit decreased optic-nerve head whole image vessel density (ONH-wiVD) and radial peripapillary capillary vessel density (RPC-VD), according to a study published in Eye and Vision. Researchers also found that the temporal and upper vessel densities are commonly impacted by early thyroid-associated ophthalmopathy (TAO).

Researchers enrolled 63 participants with TAO consisting of patients with DON (n=19), patients without DON (n=24) and patients with EDON (n=20), along with control individuals (n=34) in the analysis. Patients underwent optical coherence tomography angiography (OCTA) to measure peripapillary retinal nerve fiber layer (p-RNFL) and vessel density parameters which included ONH-wiVD and RPC-VD. The primary objective was to assess changes in blood supply and structure surrounding the optic nerve head in patients with TAO and suspected DON. 

Overall, there were no significant differences in p-RNFL thicknesses among the groups, but there were differences in both ONH-wiVD and RPC-VD in all areas (P <.01).  On subdivision, the RPC-VD in the temporal upper, superior temporal, and temporal lower sectors of the peripapillary region was decreased in patients with EDON. Visual impairment was associated with peripapillary capillary vessel density, and ONH-wiVD and RPC-VD in individuals with TAO was inversely associated with intraocular pressure (P =.006; P =.016, respectively).

Researchers state the investigation “revealed the relationship between the visual function and morphological changes of the retinal structure and microvasculature around the disc. The combined use of spectral domain OCT and OCTA technologies offer a new method for early diagnosis of the suspected DON patients, and the prediction of progression for these early DON stage to more advanced stages,” according to the report.

Study limitations include a small sample size, single center design, and failure to differentiate between eyes with acute active phase and chronic phase DON.