Technology and the Glaucoma Suspect

Abstract

Purpose: To determine and compare the diagnostic performance of spectral-domain optical coherence tomography (SD-OCT), stereoscopic disc photographs, and automated perimetry as assessed by a group of glaucoma specialists in differentiating individuals with early glaucoma from suspects.

Methods: Forty-six eyes (46 patients) with suspicious optic nerves had previously undergone SD-OCT scans, 24-2 visual fields (VFs), and optic disc photographs. The average VF mean deviation was -1.97 ± 2.09 (SD) dB. Four glaucoma specialists examined the 138 individual diagnostic tests and classified the patient as likely glaucomatous or nonglaucomatous based on the results of a single test. The diagnostic performances of each of the three tests were compared to a previously determined reference standard, based on the consensus of a separate panel of four glaucoma specialists who examined all three tests together.

Results: Among the four specialists, the interobserver agreement across the three diagnostic tests was poor for VF and photos, with kappa (κ) values of 0.13 and 0.16, respectively, and moderate for OCT, with κ value of 0.40. Using panel consensus as reference standard, OCT had the highest discriminative ability, with an area under the curve (AUC) of 0.99 (95% 0.96-1.0) compared to photograph AUC 0.85 (95% 0.73-0.96) and VF AUC 0.86 (95% 0.76-0.96), suggestive of closer performance to that of a group of glaucoma specialists.

Conclusions: Compared to VF and disc photography, SD-OCT, when used alone, had better internal agreement as well as better agreement with the consensus of clinicians using all available data. Future studies should evaluate best practices for SD-OCT interpretation.

Figure 1

Optic disc photograph, visual field, and SD-OCT for representative patient A.

Figure 2

Area under the curve for the highest-performing rater and the summed, composite, measure. A nonparametric ROC analysis using the reference standard was performed, with the binary classification scores (0 = control, 1 = glaucoma) defined by each rater using each test modality as the predictors, followed by calculation of AUC ROC values for each rater for each test. The blue line corresponds to VF, red to photos, and green to OCT, and the straight green line to the reference standard, with AUC values shown in the legend. (A) Curves and AUC values are shown for the highest-performing specialist. AUC for VF was 0.78, for photo was 0.85, and for OCT was 0.95. (B) For the analysis of the performance of each test modality, the scores from each rater were summed to a composite, ordinal measure. Curves and AUC values are shown for each diagnostic test summed across all specialists. AUC for VF was 0.86, for photo was 0.85, and for OCT was 0.99.