title: Scanning laser polarimetry reveals status of RNFL integrity in eyes with optic nerve head swelling by OCT.
abstract: OBJECTIVE
  Optical coherence tomography (OCT) shows retinal nerve fiber layer (RNFL) thickening in optic nerve head (ONH) swelling, but does not provide information on acute axonal disruption. It was hypothesized that scanning laser polarimetry (SLP) compared with OCT might reveal the status of axon integrity and visual prognosis in acute RNFL swelling.
  
  
  METHODS
  Threshold perimetry, OCT, and SLP were used to prospectively study eyes with papilledema (24), optic neuritis (14), nonarteritic anterior ischemic optic neuropathy (NAION) (21), and ONH swelling (average RNFL value by OCT was above the 95th percentile of controls at presentation). Regional RNFL was judged reduced if the quadrant measurement was below the fifth percentile of controls.
  
  
  RESULTS
  At presentation, average RNFL by OCT was similar for eyes with papilledema and NAION (P = 0.97), and reduced for optic neuritis. Average RNFL by SLP was slightly increased for papilledema and optic neuritis, and reduced for NAION (P = 0.02) eyes. The RNFL by SLP was reduced in at least one quadrant in 1 eye with papilledema, 1 eye with optic neuritis, and in 13 eyes with NAION. In NAION eyes, quadrants with reduced SLP had corresponding visual field loss that did not recover. By one month, eyes with NAION showed RNFL thinning by OCT (7/17 eyes) and by SLP (14/16 eyes) in contrast to optic neuritis (by OCT, 0/12, P = 0.006; and by SLP, 1/12, P = 0.0004).
  
  
  CONCLUSIONS
  OCT and SLP revealed different aspects of RNFL changes associated with ONH swelling. OCT revealed thickening due to edema. SLP revealed a decrease in retardance in eyes with axonal injury associated with visual field loss, which is unlikely to recover.
authors.affiliation: New York Eye and Ear Infirmary and INN at Roosevelt Hospital, New York, New York 10019, USA. mkuper@chpnet.org
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Kupersmith
authors.forename: Randy
authors.initials: R
authors.lastname: Kardon
authors.forename: Mary
authors.initials: M
authors.lastname: Durbin
authors.forename: Melissa
authors.initials: M
authors.lastname: Horne
authors.forename: Julia
authors.initials: J
authors.lastname: Shulman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009898:Optic Disk / Q000473:pathology*; D009902:Optic Neuritis / Q000209:etiology / Q000473:pathology*; D010211:Papilledema / Q000150:complications / Q000473:pathology*; D015203:Reproducibility of Results; D012165:Retinal Ganglion Cells / Q000473:pathology*; D057109:Scanning Laser Polarimetry / Q000379:methods*; D041623:Tomography, Optical Coherence / Q000379:methods*; D055815:Young Adult