BACKGROUND AND PURPOSE: Although previous animal studies have shown structural changes in ocular hypertension such as atrophy of the LGN, such changes have not been thoroughly studied in human glaucoma patients nor correlation made with clinical stage. Our aim was to investigate prospectively LGN atrophy in patients with POAG using 3T MR imaging and correlation with the clinical stage of disease. MATERIALS AND METHODS: Twenty-six patients with known POAG and 26 age-matched healthy volunteers were included in this institutional review board-approved study. All subjects underwent imaging on a 3T MR imaging system with a PD and GM sequence. LGN height and volume were measured by 2 blinded neuroradiologists. Measurements were compared and correlated with clinical glaucoma severity as assessed by static threshold visual field parameters. RESULTS: Average maximum LGN height in patients with glaucoma on PD images was 4.36 +/- 0.61 mm (right) and 4.31 +/- 0.61 mm (left), significantly less (P < 10(-3)) than respective measurements of 5.05 +/- 0.41 and 4.99 +/- 0.41 mm in volunteers. With the GM sequences, such respective measurements were also less (P < 10(-3)) in patients with glaucoma (4.20 +/- 0.71 mm right, 4.00 +/- 0.85 mm left) versus respective measurements in volunteers (4.88 +/- 0.51 mm right, 4.77 +/- 0.47 mm left). Average LGN volumes in the patient group were 98.0 +/- 27.2 mm(3) (right) and 93.7 +/- 25.8 mm(3) (left) with the PD sequence versus respective measurements of 85.2 +/- 27.1 and 80.5 +/- 23.6 mm(3) with the GM sequence. All height and volume measurements were greater in volunteers (P < 10(-3)). In the patient group, both maximum height and volume of the LGN with both sequences were significantly correlated with cumulative clinical glaucoma stage (P < .05). CONCLUSIONS: MR imaging measurements of LGN height and volume are diminished in patients with glaucoma, with the extent of atrophy correlating to clinical stage, suggesting a novel imaging marker of disease severity.