Retinal nerve fiber layer evaluation in open-angle glaucoma. Optimum criteria for optical coherence tomography.

PURPOSE: To determine the optimum criteria for optical coherence tomography (OCT) to discriminate best between healthy and glaucomatous eyes. DESIGN: A prospective cross-sectional study. METHODS: In total, 164 eyes selected from clinical practice were included in this study. These were classified into 98 healthy and 66 glaucomatous eyes, depending on the intraocular pressure, appearance of the optic disc and standard automated perimetry results. Only 1 eye per subject was randomly included. The retinal nerve fiber layer (RNFL) was evaluated by means of OCT (Stratus OCT 3000). The sensitivity and specificity values of different diagnostic criteria (4 abnormal quadrants and 1-5 abnormal clock-hours) were calculated with different probability levels (p < 0.05 and p < 0.01). RESULTS: The criterion with the best sensitivity-specificity balance was the presence of >or=2 hour positions with an RNFL thickness outside of the 95% confidence interval (CI; sensitivity = 77.2%, specificity = 91.9%). For the 99% CI, the best criterion was the presence of at least 1 abnormal hour position (sensitivity = 71.2%, specificity = 91%). Regarding retinal quadrants, the presence of at least 1 quadrant with RNFL thickness outside of the CI was the criterion that best discriminated the existence of glaucomatous damage. CONCLUSIONS: The definition of diagnostic criteria based on OCT structural parameters may improve its diagnostic ability. The highest diagnostic ability was provided by the presence of at least 2 hour positions or RNFL average thickness outside the 95% CI.

Frequency-doubling technology: searching for the optimum diagnostic criteria for glaucoma.

PURPOSE: To determine the diagnostic criteria of perimetry using frequency-doubling technology (FDT) with the best possible sensitivity-specificity balance for glaucoma diagnosis. METHODS: A total of 92 healthy control subjects and 110 patients with varying degrees of glaucomatous visual field loss on standard automated perimetry (SAP) were used to obtain the best diagnostic criterion for the disease, by using screening C-20-1 and threshold C-20 strategies from original FDT perimetry. Another prospective sample of 52 normal eyes and 64 glaucoma eyes was used to test how well this optimum criterion performs in other populations. Receiver operating characteristic (ROC) curves were plotted for the number of altered points at each level of probability for the C-20-1 and threshold C-20 modes. In addition, ROC curves were calculated for the global indices of the threshold C-20 strategy. RESULTS: The best criterion for the C-20-1 strategy is the presence of one or more altered points with p < 1% (57.81% sensitivity and 100% specificity). The optimum criteria for glaucoma diagnosis for the threshold C-20 strategy are the presence of five or more altered points with p < 5% and/or two or more altered points with p < 2% and/or at least one altered point with p < 1% at any location (79.68% sensitivity and 94.2% specificity). CONCLUSIONS: By using the C-20-1 strategy, a p < 1% defect anywhere showed 100% specificity with the lowest test duration. The criteria proposed for the threshold C-20 algorithm presented a good sensitivity-specificity balance. The threshold C-20 test provides higher sensitivity than the C-20-1 strategy but takes about five times longer to perform.