Assessment of optic disc photographs for glaucoma by UK optometrists: the Moorfields Optic Disc Assessment Study (MODAS)

Abstract

To assess the ability of UK optometrists to accurately discriminate between stereoscopic photographs of healthy and glaucomatous optic discs. An online survey, including questions relating to qualification, practice environment, and diagnostic methods was completed by 1256 optometrists. Based on their responses, 208 (17%) were selected to undertake an online disc assessment exercise. Optometrists evaluated the same disc images previously assessed by European ophthalmologists as part of the European Optic Disc Assessment Trial (EODAT); the task was to state if the disc appeared healthy or glaucomatous. There were 110 stereoscopic disc images, of which 40 were healthy, 48 glaucomatous, and six ocular hypertensive, with 16 duplicates images. Sensitivity, specificity and overall accuracy were calculated and compared between optometrist groups and with the EODAT ophthalmologists using permutation analysis. Median sensitivity was 0.92 (95% CI: 0.70, 1.00) and median specificity was 0.74 (95% CI: 0.62, 0.88). Median overall accuracy was 80% (95% CI: 67%, 88%). Agreement between optometrists was moderate (Fleiss' κ: 0.57). Optometrists with higher qualifications did not have overall higher sensitivity than those without (p=0.23), but had higher specificity (p=0.001) and higher overall accuracy (p<0.001). Optometrists displayed higher sensitivity but lower specificity than the EODAT ophthalmologists. UK optometrists displayed a high sensitivity and moderate specificity when assessing optic discs for the presence of glaucoma, in the context of this study.