Conventional MRI and magnetisation transfer imaging of the brain and optic pathway in primary open-angle glaucoma.

Neuropathological studies in experimental and human glaucoma have shown degenerative changes in the optic pathway. The purpose of the study was to evaluate, with conventional MRI and magnetisation transfer imaging, the brain and the optic pathway of patients with primary open-angle glaucoma (POAG). 26 patients, aged 67.4+/-8.6 years, and 26 control subjects were studied. The presence of white matter hyperintensities (WMH) was evaluated on fluid-attenuated inversion recovery images of the brain. The area of the optic nerves was assessed on coronal short tau inversion recovery images. Magnetisation transfer ratio (MTR) was measured in the chiasm and in the grey and white matter (CGM and CWM) of the calcarine fissure. More WMH were observed in patients (total 261, mean 10.8, standard deviation 12.7) than in control subjects (total 127, mean 4.7, standard deviation 5.7; p<0.001). The area (mm(2)) of optic nerves (10.7+/-5.7) and the MTR (%) of the chiasm (53.7+/-8.4), the CWM (60.9+/-4.2) and the CGM (53.6+/-5.6) were all lower in patients than in control subjects (13.6+/-4.3, 62.1+/-6.2, 67.6+/-8.6 and 57.0+/-4.6, respectively; p<0.05). The area of optic nerves showed significant correlation with the MTR of the chiasm (R = 0.41), the MTR of the CGM (R = 0.33), the MTR of the CWM (R = 0.34) and the cup to disc ratio (R = -0.46). POAG leads to optic nerve atrophy and degeneration of the optic pathway. The finding of an increase in the number of WMH suggests that cerebrovascular disease may play a role in the pathogenesis of POAG.