title: The Optic Canal Size Is Associated With the Severity of Papilledema and Poor Visual Function in Idiopathic Intracranial Hypertension.
abstract: To determine whether the size of the bony optic canal is associated with the severity of papilledema and poor visual function in idiopathic intracranial hypertension (IIH).
  
  
  
  We performed a retrospective review of definite patients with IIH with requisite brain magnetic resonance imaging allowing for optic canal measurement. Clinical characteristics and automated (Humphrey) visual field results were reviewed; papilledema was graded according to the modified Frisén scale. Cross-sectional area of the optic canals was measured independently by 2 readers and averaged for each canal. Logistic regression modeling was applied.
  
  
  
  Sixty-nine patients with IIH were included (mean age: 33; 91% women; 65% black). Controlling for age, sex, body mass index, race, and cerebrospinal fluid (CSF) opening pressure, each mm increase in canal size was associated with a 0.50 dB reduction in Humphrey visual field mean deviation (P = 0.006); this was likely mediated by the increased odds of Grade 4-5 papilledema or optic atrophy in patients with larger canals (odds ratio: 1.30 [95% CI: 1.10-1.55; P = 0.003] for Grade 4-5 papilledema or atrophy vs grade <4 papilledema per mm increase in canal size).
  
  
  
  Poor visual function and severe papilledema or optic atrophy were associated with a larger optic canal. Potential mechanisms include alteration of local CSF flow or bony remodeling at the optic canals.
authors.affiliation: Departments of Ophthalmology (SB, LC, NJN, VB, BBB), Radiology and Imaging Science (AMS), Neurology (NJN, VB, BBB), and Neurological Surgery (NJN), Emory University School of Medicine, Atlanta, Georgia; and Department of Epidemiology (BBB), Rollins School of Public Health and Laney Graduate School, Emory University, Atlanta, Georgia.
authors.forename: Samuel
authors.initials: S
authors.lastname: Bidot
authors.forename: Lindsay
authors.initials: L
authors.lastname: Clough
authors.forename: Amit M
authors.initials: AM
authors.lastname: Saindane
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Newman
authors.forename: Valérie
authors.initials: V
authors.lastname: Biousse
authors.forename: Beau B
authors.initials: BB
authors.lastname: Bruce
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology; D015170:Cerebrospinal Fluid Pressure / Q000502:physiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009900:Optic Nerve / Q000473:pathology*; D010211:Papilledema / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D011559:Pseudotumor Cerebri / Q000150:complications* / Q000175:diagnosis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D014792:Visual Acuity; D014794:Visual Fields