AIM: To assess the changes of vessel density in the optic disc and macular of the affected eye and the uninvolved contralateral eye in patients with idiopathic optic neuritis(ON)and to provide clinical guidance for the treatment and follow-up of idiopathic ON.

METHODS: A total of 16 patients with first-episode monocular idiopathic ON ≤3 mo diagnosed between December 2019 and December 2021 were included in this cross-sectional study. The eye of patients was divided into 16 eyes in the affected eye group and 16 eyes in the uninvolved contralateral eye group, and 20 healthy age-matched eyes(n=20)served as controls. Optical coherence tomography angiography(OCTA)was performed in all eyes at 4.5 mm×4.5 mm region of the optical disc and 6 mm×6 mm region of the macular, and blood flow indicators were collected and compared.

RESULTS: Compared with the control group and the uninvolved contralateral eye group, the density of all vessels and capillary were reduced in the whole area of optic disc, and all subdivisions of the peripapillary region in the ON group(all P<0.05). Compared with the uninvolved contralateral eye group, the density of superficial capillary plexus(SCP)was significantly lower in the whole area of macular and perifovea region, and its all subdivisions of the ON eye, as well as in the superior-hemi and superior subdivision of the parafovea region(all P<0.05). Compared with the control group, the density of SCP in the inferior-hemi, nasal, and inferior perifovea region was significantly reduced in the ON affected eye group(all P<0.05). Compared with the control group, the whole area of macular and its subdivisions in the uninvolved contralateral eye group showed an increase in the density of SCP(P<0.05)and an increase in the density of SCP in the parafovea region(P<0.05), but no significant change in the inferior-hemi and nasal subdivisions; the increase in the density of SCP in the perifovea region was only significant in the superior-hemi and superior subdivisions(P<0.05).

CONCLUSION: Patients with ON in the duration of ≤3 mo may showed a decreased vessel density in all peripapillary subdivisions, and a decreased density of SCP in some subdivisions of the perifovea region, accompanied by an increased density of SCP in some subdivisions of the macular region of the contralateral eyes.