Agreement and accuracy of non-expert ophthalmologists in assessing glaucomatous changes in serial stereo optic disc photographs.
OBJECTIVE
To compare the interobserver agreement in detecting glaucomatous optic disc changes using serial stereophotography between a large group of non-expert ophthalmologists and glaucoma specialists; to assess the accuracy of non-experts; to investigate whether the interobserver agreement and the accuracy of non-experts changed after a training session.


METHODS
Masked interobserver agreement study.


METHODS
Serial optic disc stereophotos from 40 patients with glaucoma.


METHODS
Three independent experienced glaucoma specialists (readers of the European Glaucoma Prevention Study) evaluated a set of 2 serial optic disc color stereo-slides for glaucomatous change, obtained with a delay varying from 2 to 7 years of 40 patients, masked from the temporal sequence of the slides. Each patient was graded as changed or stable by agreement of 2 of 3 of the experts (the reference standard). Thirty-seven non-expert ophthalmologists independently evaluated the same set of serial optic disc stereo-slides twice, with the second evaluation on the same day, masked from the results of the previous evaluation, after a training session on a separate slide set.


METHODS
Interobserver agreement of non-experts and experts in detecting glaucomatous optic disc changes (expressed as kappa coefficient); agreement of non-experts with the reference standard (accuracy) before and after a training session.


RESULTS
The interobserver kappa coefficient (κ) of the non-experts and experts was 0.20 (95% confidence interval [CI], 0.19-0.21) and 0.51 (95% CI, 0.33-0.69), respectively (P<0.0001). The mean κ of the non-experts with the reference standard was 0.33 (95% CI, 0.27-0.39). After a training session, the interobserver agreement of the non-experts increased from 0.20 to 0.27 (95% CI, 0.26-0.28) (P<0.0001). The percentage agreement of the non-experts with the reference standard improved from 68.5% before to 71.4% after the training session (Wilcoxon signed-rank test, P=0.034).


CONCLUSIONS
The interobserver agreement of non-expert ophthalmologists in detecting glaucomatous optic disc changes using serial stereophotos was significantly lower than that of experts, which was moderate. After a training session, the interobserver agreement and the accuracy of the non-experts showed a small but statistically significant improvement.
Department of Ophthalmology, Leuven University Hospitals, Leuven, Belgium.
Christophe
C
Breusegem
Steffen
S
Fieuws
Ingeborg
I
Stalmans
Thierry
T
Zeyen
D003941:Diagnostic Techniques, Ophthalmological; D005104:Expert Testimony / Q000592:standards*; D005901:Glaucoma / Q000145:classification / Q000175:diagnosis*; D006801:Humans; D015588:Observer Variation; D009885:Ophthalmology / Q000706:statistics & numerical data*; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000145:classification / Q000175:diagnosis*; D010781:Photography / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity