title: Scanning laser polarimetry of the retinal nerve fiber layer in perimetrically unaffected eyes of glaucoma patients.
abstract: OBJECTIVE
  To compare scanning laser polarimetry (SLP) measurements of retinal nerve fiber layer (RNFL) thickness in perimetrically unaffected eyes of glaucoma patients with those in their fellow eyes with field loss and eyes of healthy subjects.
  
  
  METHODS
  Observational case-control study.
  
  
  METHODS
  Twenty-three glaucoma patients with a reproducible visual field (VF) defect in one eye (mean mean deviation [MD], -5.71 decibels [dB]) and a normal VF in the other one (i.e., < or =1 VF test point below the 5% probability level [mean MD, -0.01 dB]) and 73 control eyes of as many age-matched healthy subjects (mean MD, 0.39 dB). The MDs and pattern standard deviations of the glaucoma patients' eyes with normal VFs and the control eyes did not statistically significantly differ (independent samples t test, P = 0.15 and P = 0.61, respectively).
  
  
  METHODS
  All subjects were measured in both eyes with the GDxVCC, a commercially available instrument featuring SLP with automated variable corneal compensation. Standard automated perimetry was assessed by means of the Humphrey Field Analyzer (24-2 Full Threshold or Swedish interactive threshold algorithm Standard achromatic test program).
  
  
  METHODS
  The standard GDxVCC parameters TSNIT (temporal, superior, nasal, inferior, temporal) Average, Superior Average, Inferior Average, TSNIT Std. Dev., and Nerve Fiber Indicator (NFI) were determined. We also assessed the thickness values in 6 parapapillary sectors. In addition, we calculated the proportion of eyes per group with an NFI of > or =40.
  
  
  RESULTS
  GDxVCC measurements showed more RNFL thinning in the perimetrically unaffected eyes of glaucoma patients than in the healthy control eyes. The RNFL in the perimetrically unaffected eyes of glaucoma patients was thicker than that in their fellow eyes with field loss. The NFI had a value of > or =40 in 11 of 23 (47.8%) perimetrically unaffected eyes of glaucoma patients, 19 of 23 (82.6%) eyes with VF loss of glaucoma patients, and 3 of 73 (4.1%) healthy control eyes.
  
  
  CONCLUSIONS
  With the GDxVCC, thinning of the RNFL may be detected in perimetrically unaffected eyes of glaucoma patients with field loss in their fellow eyes.
authors.affiliation: Glaucoma Service, The Rotterdam Eye Hospital, Rotterdam, The Netherlands. reus@oogziekenhuis.nl
authors.forename: Nicolaas J
authors.initials: NJ
authors.lastname: Reus
authors.forename: Hans G
authors.initials: HG
authors.lastname: Lemij
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D005902:Glaucoma, Open-Angle / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure; D007834:Lasers; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis*; D012165:Retinal Ganglion Cells / Q000473:pathology*; D014065:Tonometry, Ocular; D014786:Vision Disorders / Q000175:diagnosis*; D058609:Visual Field Tests; D014794:Visual Fields