Article
Intra- and interobserver reproducibility of the Retinal Thickness Analyzer (RTA) in healthy eyes
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Published: | September 22, 2004 |
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Outline
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Objective
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.
Methods
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.
Results
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).
Conclusions
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.