Comparison of optic nerve imaging methods to distinguish normal eyes from those with glaucoma

To compare the ability of qualitative assessment of optic nerve head stereophotographs (ONHPs), confocal scanning laser ophthalmoscopy (CSLO), scanning laser polarimetry (SLP), and optical coherence tomography (OCT) to distinguish normal eyes from those with early to moderate glaucomatous visual field defects.

Eighty-nine eyes (63 normal, 63 age-matched with glaucoma) of 89 subjects more than 40 years of age were studied. Receiver operating characteristic (ROC) curves were generated from discriminant analysis of CSLO, SLP, and OCT measurements and from ONHP scores. Sensitivity at 80% and specificity at 90% were calculated. Differences between individual methods and combinations of methods were assessed for statistical significance. Agreement on categorization between methods (kappa) was assessed.

The average visual field mean deviation (MD +/- SD) in patients with glaucoma was -3.9 +/- 2.2 dB, and the average pattern standard deviation (PSD) was 4.7 +/- 3.4 dB. In normal subjects the average MD was 0.1 +/- 0.9 dB and the average PSD was 1.5 +/- 0.3 dB. Optimal sensitivities, specificities, and areas under ROC curves were, respectively: ONHP (0.94, 0.87, 0.93), CSLO (0.84, 0.90, 0.92), SLP (0.89, 0.87, 0.94), and OCT (0.82, 0.84, 0.88). Best agreement on categorization (kappa) was between ONHPs and CSLO (0.70). The ROC area for the combination of methods was 0.99, higher than for any method alone. The ROC area for the combination of methods was significantly better than the CLSO rim area (P = 0.012) and the OCT retinal nerve fiber layer (RNFL) thickness (P = 0.002).

The quantitative methods CSLO, SLP, and OCT were no better than qualitative assessment of disc ONHPs by experienced observers at distinguishing normal eyes from those with early to moderate glaucoma. A combination of the imaging methods significantly improves this capability.