MAGNETIC-RESONANCE-IMAGING IN PATIENTS WITH LOW-TENSION GLAUCOMA

Objective. To study diagnoses and anatomic findings found on magnetic resonance imaging in patients with low-tension glaucoma. Patients: We included in this study magnetic resonance images of 20 consecutive pat ients 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 pa thway. Design: We studied axial and coronal images of the orbit and op tic 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. Res ults: We found no difference between groups in the optic nerve diamete r or length, the carotid artery area, or the distance from the optic n erve to the carotid artery (P > .05). Left optic nerve area was greate r in the control patients than patients with low-tension glaucoma (P = .026). The prevalence of intracranial abnormalities, including mening ioma, aneurysm, and arteriovenous abnormality, was similar between gro ups (P > .05). However, diffuse cerebral small-vessel ischemic changes were found more in patients with low-tension glaucoma (n = 8) than co ntrol patients (n = 1) (P = .0196). Conclusions: This study proposes a hypothesis that cerebral small-vessel ischemia is more common in pati ents with low-tension glaucoma and potentially reflects indirectly a v ascular 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.