title: Anterior visual pathway assessment by magnetic resonance imaging in normal-pressure glaucoma.
abstract: OBJECTIVE
  To analyze the axonal architecture of the optic nerve in patients with normal-pressure glaucoma and determine whether these parameters correlate with the disease severity.
  
  
  METHODS
  Using magnetic resonance (MRI) imaging (1.5-Tesla unit) and diffusion tensor (DT) MRI, we measured the optic nerve diameter, optic chiasm height and lateral geniculate nucleus (LGN) volume in patients with normal-pressure glaucoma and an age-matched control group. The retinal nerve fibre layer thickness (RNFL) was determined by optical coherence tomography (OCT).
  
  
  RESULTS
  The study included 30 patients with normal-pressure glaucoma and 30 age-matched control subjects. Optic nerve diameter (p < 0.001), optic chiasm height (p < 0.001) and LGN volume (p = 0.02) were significantly smaller in the glaucoma group than in the control group and were significantly correlated with RNFL thickness and perimetric loss. In the control group, the parameters significantly (p < 0.05) decreased with age. The DT-MRI-derived fractional anisotropy for the optic nerve was significantly lower (p < 0.001), and the DT-MRI-derived mean diffusivity (p < 0.001), radial diffusivity (λ(⊥) ; p < 0.001) and axial diffusivity (λ(||) ; p = 0.009) for the optic nerve were significantly higher in the glaucoma group and significantly correlated with RNFL thickness and mean perimetric defect.
  
  
  CONCLUSIONS
  Patients with normal-pressure glaucoma show an age-adjusted reduced optic nerve diameter, optic chiasm height and LGN volume as measured by MRI, correlating with a reduced RNFL thickness and increased perimetric loss. MRI may be applied to examine the optic nerve in patients with glaucoma with opaque optic media.
authors.affiliation: Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, China.
authors.forename: Ya Q
authors.initials: YQ
authors.lastname: Zhang
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Liang
authors.initials: L
authors.lastname: Xu
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Zhen C
authors.initials: ZC
authors.lastname: Wang
authors.forename: Hua
authors.initials: H
authors.lastname: Yang
authors.forename: Chang X
authors.initials: CX
authors.lastname: Chen
authors.forename: Xi S
authors.initials: XS
authors.lastname: Wu
authors.forename: Jost B
authors.initials: JB
authors.lastname: Jonas
mesh_terms: D000328:Adult; D000368:Aged; D001369:Axons / Q000473:pathology; D005260:Female; D005829:Geniculate Bodies / Q000473:pathology*; D006801:Humans; D007429:Intraocular Pressure; D057066:Low Tension Glaucoma / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology; D009897:Optic Chiasm / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis*; D011446:Prospective Studies; D012165:Retinal Ganglion Cells / Q000473:pathology; D041623:Tomography, Optical Coherence; D014794:Visual Fields; D014795:Visual Pathways / Q000473:pathology*