gms | German Medical Science

102. Jahrestagung der DOG

Deutsche Ophthalmologische Gesellschaft e. V.

23. bis 26.09.2004, Berlin

Intra- and interobserver reproducibility of the Retinal Thickness Analyzer (RTA) in healthy eyes

Meeting Abstract

  • corresponding author C. Kramann - Department of Ophthalmology, University of Mainz
  • E. M. Hoffmann - Department of Ophthalmology, University of Mainz
  • F. Krummenauer - Department for Medical Biometry, Epidemiology and Informatics, University of Mainz
  • F. H. Grus - Department of Ophthalmology, University of Mainz
  • N. Pfeiffer - Department of Ophthalmology, University of Mainz

Evidenzbasierte Medizin - Anspruch und Wirklichkeit. 102. Jahrestagung der Deutschen Ophthalmologischen Gesellschaft. Berlin, 23.-26.09.2004. Düsseldorf, Köln: German Medical Science; 2004. Doc04dogP 137

The electronic version of this article is the complete one and can be found online at:

Published: September 22, 2004

© 2004 Kramann et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.




To determine the reproducibility of mean retinal nerve fiber layer (RNFL) thickness measurements obtained with the Retinal Thickness Analyzer (RTA) by both experienced and inexperienced examiners.


39 healthy volunteers (=39 eyes) were included in the study. Three examiners (two experienced and one inexperienced) performed RTA analysis along three measurement replications in a randomized order. The scanned region ("Glaucoma-Disc") included three quadrants at the disc, and one quadrant in the papillomacular region, each of 3x3 mm2 size. Inter- and intra-observer deviations were described via medians and quartiles of intraindividual differences; Friedman tests (intra) and sign tests (pairwise inter-observer comparisons) were applied to test for significant deviations between or within the observers' measurement replications. p<0.05 denotes locally significant deviations.


The intra-observer examinations revealed median deviations of 0.01 (interquartile range -0.03 ; 0.03) between the experienced and 0.01 (-0.04 ; 0.03) and 0.01 (-0.03 ; 0.02) compared with the inexperienced observer regarding the MRNFL. For the inexperienced observer, the median of the three measurement replications varied between 0.10 and 0.12, for the experienced observers between 0.11 and 0.13, and 0.10 and 0.13, respectively. One of the experienced observer showed a smaller intra-observer reliability (MRNFL) than both of the other observers (Friedman p=0.137 versus p=0.535 and p=0.571). For this parameter no statistically significant pairwise interobserver deviations were observed (pairwise sign p=0.664, 0.824, 0.824, respectively).


The results suggests that optic disc topography by RTA may provide good intra- and inter- observer reproducibility among healthy eyes. Furthermore, the results were highly reproducible, even if one examiner is inexperienced with the instrument.