Comparison of three types of images for the detection of retinal nerve fiber layer defects

Purpose. To compare the clinical effectiveness of three types of images for detecting retinal nerve fiber layer (RNFL) defects. Methods. Three image sets of 100 subjects (9 normal control subjects, 16 glaucoma suspects, and 75 glaucoma patients) were produced using color fundus photography, typical red-free RNFL photography, and blue reflectance RNFL photography with confocal scanning laser ophthalmoscopy (CSLO). A total of 300 images were rated twice in random order by five independent evaluators who were masked to the patient characteristics; each image was rated as normal, having a diffuse RNFL defect, or showing a wedge RNFL defect. Intraobserver and interobserver agreement, sensitivity, specificity, accuracy, and area under the curve were assessed. An additional analysis was performed for identifying differences in two black-and-white RNFL photographs. Results. The results showed high intraobserver agreement, with relatively low interobserver agreements among the five evaluators. Blue reflectance RNFL photography with CSLO demonstrated the best performance in sensitivity, specificity, accuracy, and area under the curve. Blue reflectance RNFL images showed better accuracy than red-free RNFL images especially in subjects with wedge defects and in advanced glaucomatous cases. Conclusions. The RNFL images produced using blue reflectance with CSLO showed the best performance for the detection of RNFL defects, especially in cases with wedge defects and advanced glaucoma stages.