Incidence of optic nerve kinking in a cohort of patients with Normal tension glaucoma.

Objectives: To report on the incidence of optic nerve kinking in a series of patients diagnosed with normal-tension glaucoma (NTG) compared to an age- and gender matched control group without known optic nerve diseases.

Subjects and methods: All patients with NTG who underwent imaging (computed tomography cysternography (CTC) or magnetic resonance imaging (MRI)) of the orbits and cranium between 2012 and 2022 were included, totalling 57 patients (27 females and 30 males; 57 eyes; mean age 69 ± 10 years). 57 age- and gender matched subjects without known optic nerve diseases who underwent MRI of the orbits and cranium served as controls. Radiographic images of the orbits were analysed for the presence of optic nerve kinking.

Results: In the axial plane at least one optic nerve kink was found in 49 of 57 (86%) optic nerves in patients with NTG and in 10 of 57 (18%) optic nerves in controls (p < 0.0001) while in the sagittal plane in 28 of 57 (49%) optic nerves in patients with NTG and in 1 of 57 (2%) optic nerves in controls (p < 0.0001) (Fisher's two-tailed exact test).

Conclusions: This study demonstrates a high statistically significant incidence of optic nerve kinking in patients with NTG compared to controls without known optic nerve diseases. Its possible role involved in the pathophysiology of NTG needs to be evaluated.