Abnormal Functional Connectivity Density in Patients with Dysthyroid Optic Neuropathy

Abstract

Objective: Functional connectivity density (FCD) mapping was used to investigate abnormalities and factors related to brain functional connectivity in cortical regions of patients with dysthyroid optic neuropathy (DON) and to analyze the pathogenesis of DON further.

Methods: Patients diagnosed with thyroid-associated opthalmology (TAO) in the Eye Hospital were enrolled. All patients underwent comprehensive eye examinations and best-corrected visual acuity, visual field (VF) test. MRI data collection and analysis were completed in the 2nd Affiliated Hospital of Wenzhou Medical University. The patients were divided into 2 groups: the DON group, with an average VF, mean deviation (MD) of both eyes < -5 dB, and the non-DON group (nDON group), with an average VF MD of both eyes ≥ -2 dB.

Results: A total of 30 TAO patients (14 men, 16 women) with complete data who met the experimental requirements were enrolled. The average age was 48.79 (40-57) years. There were 16 patients in the DON group and 14 patients in the nDON group. No significant differences in age, gender, education level, and the maximum horizontal diameter of either medial rectus muscle were found between the 2 groups. The difference of brain FCD between the 2 groups showed significant abnormal connectivity in the right orbital gyri of the frontal lobe (Frontal_Inf_Orb_R) and the left precuneus in the DON group compared with the nDON group. As demonstrated by decreased FCD values in the right inferior frontal gyrus/orbital part, the relevant brain regions were the left middle temporal gyrus, left precuneus, left middle frontal gyrus, right postcentral gyrus, and brain gyri (excluding the supramarginal gyrus and angular gyrus) below the left parietal bone. The FCD associated with the left precuneus was increased, and the relevant brain areas were the left middle temporal gyrus, right cuneus, superior occipital gyrus, and right fusiform gyrus. A significant correlation was identified between the MD of the binocular VF and brain FCD.

Conclusion: The abnormal FCD in the cortex of DON patients suggests that a central nervous system mechanism may be related to the pathogenesis of the DON.

Keywords: Dysthyroid optic neuropathy; Functional connectivity density; Thyroid-associated ophthalmology.