Abstract
The aim of our study was to determine whether magnetic resonance imaging (MRI) could demonstrate changes to the anterior visual pathway in normal-tension glaucoma (NTG) with regard to optic nerve diameter (OND), optic nerve sheath diameter (OSD) and optic chiasm width when compared with a control group. The study included 16 patients with NTG - ten women with a mean age of 63.6 (46-72) and six men with a mean age of 60 (47-68).
All patients underwent both a complete ophthalmologic examination and an examination of the anterior part of the visual pathway. A complete MRI examination included the T2 coronal sequences, SSh (Single Shot technique) with fat sat (fat-supressed).
We determined the OND and OSD at 4, 8, 16 and 20 mm posterior to the globe. The study group was compared to a group of 12 healthy individuals - nine women with a mean age of 50 (46-61) and three men with a mean age of 58 (54-61).
Statistical analysis (Paired t-test) did not show any differences in measured values between both optic nerves in the NTG group and the control group. When comparing the diameter values between patients with NTG and the control group (two-sample t-test), we found that the values differed for certain variables.
However, this difference could have again been purely accidental. At any rate, in all cases where the values showed statistically significant differences, the values in patients with NTG were lower than in the control group and this applied to the vast majority of other variables as well.
Conclusion: The results showed differences in measured values, but these differences were not statistically significant, except for chiasm width which had statistical significance. We believe that chiasm width is more significant for NTG than OND or OSD.