Abstract
Purpose: :
To compare the retinal nerve fiber layer (RNFL) evaluation using Cirrus optical coherence tomography (OCT) and Stratus OCT in glaucoma diagnosis.
Methods: :
One-hundred-thirty normal and 86 glaucomatous patients were included in this prospective study. The signal strength values using the OCTs were evaluated. The sensitivity/specificity of global RNFL average thickness, in the four quadrants and for each clock hour were compared. Receiver operating characteristic curves (ROC), areas under the ROC (AUC), and likelyhood ratio (LR) were plotted for RNFL thickness. Agreement between the OCTs was calculated using Bland-Altman method and k coefficient.
Results: :
Twenty-three percent of all cases using Stratus OCT and 1.9% with Cirrus OCT had signal strengths below 6 (P=0.01). In cases with signal strengths >6, the mean signal strength was higher with Cirrus OCT than with Stratus OCT (P=0.01). The RNFL measurements were thicker using Cirrus than Stratus OCT (P<0.05). The AUCs were 0.829 for Stratus and 0.837 for Cirrus OCT (P=0.706) in global RNFL average. Positive LR was higher using Cirrus than Stratus OCT in the inferior quadrant. The widths of the limits of agreement varied between 42.16 and 97.79 microns. There was substantial agreement (k, 0.74) in the average RNFL classification.
Conclusions: :
Cirrus OCT has better scan quality than Stratus OCT, especially with glaucomatous eyes. In cases with good quality scans, he sensitivity/specificity, and AUCs were similar. The best agreement was in the global average RNFL classification. The widths of limits of agreements exceed the limits of resolution of the OCTs.
Keywords: optic disc • imaging/image analysis: clinical • optic nerve