Magnetic resonance imaging in patients with low-tension glaucoma

To study diagnoses and anatomic findings found on magnetic resonance imaging in patients with low-tension glaucoma.

We included in this study magnetic resonance images of 20 consecutive patients with low-tension glaucoma. We individually matched each patient with low-tension glaucoma to a control with normal ocular findings who had magnetic resonance imaging for reasons unrelated to the visual pathway.

We studied axial and coronal images of the orbit and optic nerve with digitizing software (Image-Pro Plus, Media Cybernetics, Silver Spring, Md). Statistical evaluation was with a Wilcoxon Signed Rank Test for anatomic findings and a McNemar Test for diagnosis.

We found no difference between groups in the optic nerve diameter or length, the carotid artery area, or the distance from the optic nerve to the carotid artery (P > .05). Left optic nerve area was greater in the control patients than patients with low-tension glaucoma (P = .026). The prevalence of intracranial abnormalities, including meningioma, aneurysm, and arteriovenous abnormality, was similar between groups (P > .05). However, diffuse cerebral small-vessel ischemic changes were found more in patients with low-tension glaucoma (n = 8) than control patients (n = 1) (P = .0196).

This study proposes a hypothesis that cerebral small-vessel ischemia is more common in patients with low-tension glaucoma and potentially reflects indirectly a vascular cause of the optic nerve head damage at least in a subgroup of patients. Importantly, further research still is required to provide direct evidence for a vascular cause involved in low-tension glaucoma.