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Digital stereoscopic analysis of the optic disc: evaluation of a teaching program
Nicholas J L Sheen1, James E Morgan, Johan L Poulsen
1School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales, United Kingdom. SheenNJ@cardiff.ac.uk
Purpose:
To determine if a computer-based stereoscopic teaching program could improve optic cup/disc ratio (CDR) agreement between student observers and an expert.
Design:
Experimental study.
Participants:
Six student observers (A-F) assessed at least 30 digital stereoscopic optic disc images using a digital stereoscopic analysis program. All observers made 36 CDR measurements (every 10 degrees ) for each disc image that they assessed.
Methods:
Disc images were divided into 3 sets of 10 images (image sets 1, 2, and 3). Observers A, B, and C determined CDRs for all 3 image sets. Set 1 was examined without access to a teaching program, set 2 using a teaching program that allowed the observer to view an expert assessment of the optic disc, and set 3 after using the teaching program. Observers D, E, and F evaluated image sets 1 and 3 only and did not have access to the teaching program. Ten months later, these same observers (D-F) viewed image set 2 using the teaching program and then reassessed image set 3.
Main Outcome Measures:
Standard deviation (SD) of CDR differences between observers and an expert, the percentage of CDR observations differing > or =0.20 from those of the expert, and intraclass correlation coefficients (ICCs) between observers.
Results:
Before teaching, the average SD of differences between all observers and the expert was 0.10. After teaching, the average SD of differences between all observers and the expert was 0.057. For observers D, E, and F, the average SD of differences for image set 3 without teaching was 0.074. The percentage of all observer measurements that differed > or =0.20 from those of the expert for image set 1 was 16.7%; for set 3 after teaching, 1.7%; and for set 3 for observers D, E, and F without teaching, 10%. Interobserver ICC values for all observers were 0.37 before teaching and 0.76 after. For observers D, E, and F, the ICC value for set 3 without access to teaching was 0.69.
Conclusions:
This study suggests that an interactive digital stereoscopic teaching program improves agreement between observers and an expert when assessing CDRs.
