Functional and Morphological Changes in the Visual Pathway in Patients with Graves’ Orbitopathy

Abstract

Background: The aim of the study was to perform a functional and structural evaluation of the anterior visual pathway in patients with Graves’ Orbitopathy (GO) using electrophysiological tests and OCT, as well as to identify potential parameters that could be useful in detecting early optic nerve damage. Methods: 47 GO patients were enrolled in the study and divided into three groups, depending on their disease severity: Group 1 with mild GO, Group 2 with moderate-to-severe GO, and Group 3 with dysthyroid optic neuropathy (DON). Pattern visual evoked potential (PVEP), flash visual evoked potential (fVEP), pattern electroretinogram (pERG), and optical coherence tomography (OCT) findings were compared between the groups. Results: In the DON Group (Group 3), N75, P100, and P2 latencies were significantly extended, whereas P100, P50, and N95 amplitudes were significantly reduced as compared to the non-DON group (Groups 1 and 2). Group 3 also had significantly thinner peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC). In Group 2, as compared to Group 1, P100 amplitudes were significantly reduced for all check sizes, while P100 latency was elongated for the check size of 0.9°. Group 2 also had a significantly thinner average GCC and GCC in the superior quadrant. Conclusions: Electrophysiological examinations may be of use in diagnosis of DON. OCT findings and electrophysiological responses vary in patients with different GO severity. Including regular electrophysiological evaluation and OCT in the examination of patients with GO could be of benefit. However, more research is needed to establish the true significance of pVEP, fVEP, pERG, and OCT in monitoring patients with GO.

OCT and OCTA in dysthyroid optic neuropathy: a systematic review and meta-analysis

“…Online supplemental table S1 presents a summary of the key characteristics of the included studies. All included studies were observational studies 5 13 24–33. Eight studies were described as a prospective design5 13 24 26–28 30 33 and three studies were retrospective studies 25 29 32.…”

“…All included studies were observational studies 5 13 24–33. Eight studies were described as a prospective design5 13 24 26–28 30 33 and three studies were retrospective studies 25 29 32. TAO was diagnosed according to EUGOGO clinical practice guidelines and Bartley criteria.…”

“…Intriguingly, five articles24 25 27 28 30 reported that the PRNFL of the DON group decreased while Wu et al 32 and Guo et al 26 recorded an increasing tendency of PRNFL in the DON group than the healthy control group and non-DON group. Meta-analysis showed no difference in these three groups in terms of PRNFL overall or by region.…”

Optic nerve compression associated with visual cortex functional alteration in dysthyroid optic neuropathy: A combined orbital and brain imaging study

“…These alterations, coupled with changes in the visual cortex, may contribute to the decline in the visual functioning score in TED patients without DON in comparison to HC. 37 , 38 Additional ophthalmic assessments of visual function are essential to elucidate the specific mechanisms underlying its impact on vision.…”

“…Despite the fact that the mMI in TED patients without DON exhibited minimal changes, and that the BCVA that is primarily determined by the status of ON also remained largely unaltered, structural modifications (OND and ONSD) occurred in the intraorbital ON due to ONC. These alterations, coupled with changes in the visual cortex, may contribute to the decline in the visual functioning score in TED patients without DON in comparison to HC 37,38 . Additional ophthalmic assessments of visual function are essential to elucidate the specific mechanisms underlying its impact on vision.…”