Purpose: Brain function in patients with acute eye pain (EP) has not been extensively studied. An understanding of the alterations in short-range functional connectivity density (shortFCD) and long-range functional connectivity density (longFCD) in patients with EP remains elusive. The aim of the present study was to compare the functional connectivity density (FCD) between patients with EP and healthy controls (HCs) using resting-state functional connectivity.
Methods: A total of  40 patients with EP (26 males and 14 females) and 40 HCs (26 males and 14 females) of similar age underwent functional magnetic resonance (MR) examination at the resting state. The shortFCD and longFCD values were compared using the one-sample t-test. The differences between patients with EP and the HCs were evaluated using receiver operating characteristic (ROC) curves.
Results: In the patients with EP, significantly reduced shortFCD values were observed in the left posterior lobe of the cerebellum, right inferior parietal lobule, and left anterior lobe of the cerebellum, and significantly reduced longFCD values were observed in both the left and right posterior lobe of the cerebellum. Significantly increased shortFCD values were also observed in both superior frontal gyri (Brodmann area 6), and increased longFCD values were observed in the left inferior temporal gyrus and left superior frontal gyri (Brodmann area 11). Compared with the HCs, less reduction was noted among the shortFCD values of patients with EP in the right posterior lobe of the cerebellum, right supramarginal gyrus, left middle temporal gyrus, bilateral superior frontal gyri, and bilateral caudate nuclei.
Conclusion: EP patients shown variation of binarized shortFCD and long FCD in brain areas including premotor cortex, ventral cortical visual system, newest part of the cerebellum, cerebellum control unconscious proprioception, inhibition of involuntary movement, somatosensory association cortex, nucleus involving reward system and ventral cortical visual system which might provide an explanation of brain functional compensation for chronic eye pain and visual impairment in the EP patients.
Keywords: eye pain, magnetic resonance imaging, functional connectivity density