title: Retinotopic fMRI Reveals Visual Dysfunction and Functional Reorganization in the Visual Cortex of Mild to Moderate Glaucoma Patients.
abstract: OBJECTIVE
  To investigate retinotopic functional representation in the visual cortex of mild to moderate primary open-angle glaucoma (POAG) participants and age-matched normal volunteers using high-resolution retinotopic blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI).
  
  
  METHODS
  fMRI was performed on 9 POAG participants (61±11 y old) and 9 age-matched controls (58±5 y old) were studied. A wide-view visual presentation (±55 degrees) was used to evaluate central and peripheral vision. Cortical magnification factors and BOLD% changes as a function of eccentricity. Correlation analysis between BOLD% changes and visual field scores, and between BOLD% changes and retinal nerve fiber layer thicknesses was performed. Comparison of BOLD% changes for individual visual field quadrants between POAG subgroups and normal group was performed.
  
  
  RESULTS
  BOLD% changes of POAG participants in peripheral visual regions were reduced compared to normals but similar in central visual regions, consistent with the notion of peripheral vision being affected first and more compared to central vision. fMRI retinotopic mapping revealed enlarged representation of the parafovea in the visual cortex of POAG participants compared to normals. Cortical magnification of the central, but not peripheral, visual representation in the visual cortex was larger in POAG participants, suggesting functional remapping. BOLD% changes of individual visual field quadrants were significantly correlated with visual field scores and with retinal nerve fiber layer thickness in the corresponding quadrants.
  
  
  CONCLUSIONS
  These results support the hypothesis that there are functional alteration and remapping in the topographic representation of the visual cortex in POAG participants, and these changes are correlated with disease severity.
authors.affiliation: Department of Ophthalmology, Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhou
authors.forename: Eric R
authors.initials: ER
authors.lastname: Muir
authors.forename: Kundandeep S
authors.initials: KS
authors.lastname: Nagi
authors.forename: Steven
authors.initials: S
authors.lastname: Chalfin
authors.forename: Pavel
authors.initials: P
authors.lastname: Rodriguez
authors.forename: Timothy Q
authors.initials: TQ
authors.lastname: Duong
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005902:Glaucoma, Open-Angle / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009473:Neuronal Plasticity / Q000502:physiology*; D009900:Optic Nerve / Q000000981:diagnostic imaging* / Q000503:physiopathology; D012160:Retina / Q000000981:diagnostic imaging* / Q000503:physiopathology; D014786:Vision Disorders / Q000175:diagnosis*; D014793:Visual Cortex / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology