title: Optic nerve head circulation in nonarteritic anterior ischemic optic neuropathy and optic neuritis.
abstract: OBJECTIVE
  To quantify optic nerve head circulatory abnormalities in patients with unilateral nonarteritic anterior ischemic optic neuropathy (NAION) or optic neuritis (ON), and to assess the potential of such measurements to differentiate NAION from ON.
  
  
  METHODS
  Prospective, cross-sectional, observational study.
  
  
  METHODS
  Thirty consecutive patients with unilateral NAION, 22 consecutive patients with unilateral ON, and 50 healthy control subjects.
  
  
  METHODS
  All subjects underwent a complete neuro-ophthalmologic evaluation. The widths of Doppler-broadened frequency spectra, which are directly proportional to the speed of blood cells flowing through the capillaries of the optic nerve head, were measured at multiple sites in both eyes of each subject. The variation of Doppler broadening (DB) with age was determined in the control subjects. Doppler broadening values in the patients were compared between similar sites in affected and contralateral eyes, and between both affected and contralateral eyes and the age-adjusted values determined in the control subjects.
  
  
  METHODS
  The differences in DB between (1) the affected and contralateral eyes of the patients, (2) the patients and the control subjects, and (3) the patients with NAION and those with ON.
  
  
  RESULTS
  In NAION, DB was decreased at both temporal (-20.2% and -18.5%) and nasal (-12.8% and -12.4%) sites of the nerve head in affected eyes compared with contralateral eyes or eyes of control subjects. In ON, DB was also decreased at temporal sites (-11.3% and -9.2%) in affected eyes compared with contralateral or control eyes. At nasal sites, there were no significant differences in DB in affected eyes of ON patients compared with contralateral or control eyes. The DB decreases were significantly greater in NAION patients than in ON patients.
  
  
  CONCLUSIONS
  Optic nerve head circulatory abnormalities are present in patients with NAION or ON. This is the first demonstration of such abnormalities in ON, a finding consistent with the recent attention given to the phenomenon of axonal loss in this disease. Although there are differences in the circulatory abnormalities between the 2 diseases that provide insights into the pathophysiological mechanisms at play, they are not large enough to enable the clinician to distinguish between ON and NAION in an individual patient.
authors.affiliation: Massachusetts Eye and Ear Infirmary and Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Nathalie J
authors.initials: NJ
authors.lastname: Collignon-Robe
authors.forename: Gilbert T
authors.initials: GT
authors.lastname: Feke
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Rizzo
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001775:Blood Circulation; D001783:Blood Flow Velocity; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008297:Male; D008875:Middle Aged; D009898:Optic Disk / Q000098:blood supply*; D009902:Optic Neuritis / Q000175:diagnosis / Q000503:physiopathology*; D018917:Optic Neuropathy, Ischemic / Q000175:diagnosis / Q000503:physiopathology*; D011446:Prospective Studies; D012039:Regional Blood Flow