Abstract
Purpose: :
Evaluate the inter-observer ability to measure vertical and horizontal cup disc ratios (CDR) on digital stereoscopic pictures in a 3-dimension web based tool.
Methods: :
In a prospective, random, and masked setting, 43 stereoscopic optic nerve images from normal and glaucomatous patients with CDR ranging from 0.2 to 0.9 for vertical and horizontal were presented on a computer screen for 162 participants using a web based software. All volunteers answered the questions using appropriated red and green stereoscopic glasses. To establish a gold standard three glaucoma specialists made the same measurements for vertical and horizontal CDR of each picture using software of Zeiss Renitograph (Visucam). The mean of the three measures was used as gold standard. Inter-observed agreement was measured using Bland-Altman analysis and intraclass correlation.
Results: :
The agreement between measures of Glaucoma specialists was very high (intraclass correlation = 0.92 and 0.90 for vertical and horizontal CDR, respectively). Bland- Altman analysis showed a worse agreement for intermediate CDR values (0.60 and 0.70 for horizontal and vertical CDR, respectively) and a trend to hyperestimate the CDR around 0.7.
Conclusions: :
Despite a good agreement between the gold standard (3 Glaucomatous specialists), the absolute agreement for intermediate CDR values was very poor for both horizontal and vertical values.
Keywords: imaging/image analysis: clinical • motion-3D • optic disc