Sensitivity and reliability of objective image analysis compared to subjective grading of bulbar hyperaemia.
OBJECTIVE
To establish the sensitivity and reliability of objective image analysis in direct comparison with subjective grading of bulbar hyperaemia.


METHODS
Images of the same eyes were captured with a range of bulbar hyperaemia caused by vasodilation. The progression was recorded and 45 images extracted. The images were objectively analysed on 14 occasions using previously validated edge-detection and colour-extraction techniques. They were also graded by 14 eye-care practitioners (ECPs) and 14 non-clinicians (NCLs) using the Efron scale. Six ECPs repeated the grading on three separate occasions


RESULTS
Subjective grading was only able to differentiate images with differences in grade of 0.70-1.03 Efron units (sensitivity of 0.30-0.53), compared to 0.02-0.09 Efron units with objective techniques (sensitivity of 0.94-0.99). Significant differences were found between ECPs and individual repeats were also inconsistent (p<0.001). Objective analysis was 16x more reliable than subjective analysis. The NCLs used wider ranges of the scale but were more variable than ECPs, implying that training may have an effect on grading.


CONCLUSIONS
Objective analysis may offer a new gold standard in anterior ocular examination, and should be developed further as a clinical research tool to allow more highly powered analysis, and to enhance the clinical monitoring of anterior eye disease.
Peterson
Rachael Claire
RC
Centre for Contact Lens Research, University of Waterloo, Canada.
Wolffsohn
James Stuart
JS
D000328:Adult; D003228:Conjunctiva / Q000098:blood supply*; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D006940:Hyperemia / Q000175:diagnosis*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014665:Vasodilator Agents
D014665:Vasodilator Agents