Abstract
Purpose: :
To compare the agreement of the assessment for glaucomatous change in serial optic disc stereo photos between reading color versus black and white (B&W) stereo photos.
Methods: :
Three independent glaucoma experts evaluated for change a set of two serial 20° optic disc color stereo-photos of 40 patients. Each observer was masked to the temporal sequence of the photos. Each observer performed two evaluations at least 30 days apart, and was masked from his previous evaluation. Each patient was graded as changed or stable. The same procedure was performed with the same set of photos in B&W 2 years later. The proportion of patients graded as changing was recorded and Generalized Estimating Equations (GEE) were used to evaluate systematic differences between observers and type of photos. The intra-observer and inter-observer rating for the task with color images and B&W images was examined separately using kappa statistics. We also examined the concordance between the results from the color and B&W task.
Results: :
The median proportion of patients graded as changing by the observers using the color photos (36.3%) was significantly greater (GEE analysis: P=0.002) than when using B&W (17.5%) . The intra-observer rating and the inter-observer rating was better when using B&W images (median kappa= 0.92 and 0.73 respectively) compared to using color images (median kappa= 0.80 and 0.57 respectively) but none of the differences were statistically significant (Kappa SE: 0.16; P>0.05). The agreement between ratings when using color as compared to B&W was moderate (median kappa =0.44 SE: 0.16).
Conclusions: :
When evaluating for change in optic disc stereo photos, glaucoma experts called more change when using color compared to B&W stereo photos. Any apparent differences in the inter- and intra-observer rating using B&W compared to color photos is due to the reduction in the complexity of the task. Overall agreement between B&W and color was only moderate at best, suggesting that they cannot be interchanged.
Keywords: optic disc • imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)