Reproducibility of scanning laser polarimetry (GDx) of peripapillary retinal nerve fiber layer thickness in normal subjects

Graefes Arch Clin Exp Ophthalmol. 2001 Feb;239(2):118-21. doi: 10.1007/s004170000247.


Purpose: To assess the reproducibility of measurement of retinal nerve fiber layer (RNFL) thickness among subjects using the GDx Nerve Fiber Analyzer (NFA).

Methods: One eye of each of five young and healthy volunteers was imaged by three newly trained technicians (R.-H.P, K.-R.K., and S.-T.K.). Each volunteer was scanned six consecutive times for five independent times within a 1-month period. One composite image was selected out of three best images per session. Intra- and interoperator reproducibilities were calculated and the influence of placement of measurement ellipse by a single operator on interobserver reproducibility was also investigated.

Results: Mean coefficients of variation for total integral value of RNFL were 3.67 +/- 1.47%, 3.86 +/- 2.13%, and 4.16 +/- 1.97%, respectively for the three technicians. Interoperator variability was not statistically significant (P = 0.075), and the difference was even less if a single ellipse drawn by one operator was used in all measurements (P = 0.1528) by repeated-measures analysis of variance (ANOVA).

Conclusions: The results suggest that GDx NFA may provide acceptable intraoperator as well as interoperator reproducibility among Asian eyes.

MeSH terms

  • Adult
  • Diagnostic Techniques, Ophthalmological*
  • Humans
  • Lasers
  • Nerve Fibers*
  • Observer Variation
  • Optic Nerve / anatomy & histology*
  • Reproducibility of Results
  • Retina / anatomy & histology*