Original Article
Evaluation of retinal nerve fiber layer, optic nerve head, and macular thickness measurements for glaucoma detection using optical coherence tomography

https://doi.org/10.1016/j.ajo.2004.08.069Get rights and content

Purpose

To compare the ability of optical coherence tomography retinal nerve fiber layer (RNFL), optic nerve head, and macular thickness parameters to differentiate between healthy eyes and eyes with glaucomatous visual field loss.

Design

Observational case-control study.

Methods

Eighty-eight patients with glaucoma and 78 healthy subjects were included. All patients underwent ONH, RNFL thickness, and macular thickness scans with Stratus OCT during the same visit. ROC curves and sensitivities at fixed specificities were calculated for each parameter. A discriminant analysis was performed to develop a linear discriminant function designed to identify and combine the best parameters. This LDF was subsequently tested on an independent sample consisting of 63 eyes of 63 subjects (27 glaucomatous and 36 healthy individuals) from a different geographic area.

Results

No statistically significant difference was found between the areas under the ROC curves (AUC) for the RNFL thickness parameter with the largest AUC (inferior thickness, AUC = 0.91) and the ONH parameter with largest AUC (cup/disk area ratio, AUC = 0.88) (P = .28). The RNFL parameter inferior thickness had a significantly larger AUC than the macular thickness parameter with largest AUC (inferior outer macular thickness, AUC = 0.81) (P = .004). A combination of selected RNFL and ONH parameters resulted in the best classification function for glaucoma detection with an AUC of 0.97 when applied to the independent sample.

Conclusions

RNFL and ONH measurements had the best discriminating performance among the several Stratus OCT parameters. A combination of ONH and RNFL parameters improved the diagnostic accuracy for glaucoma detection using this instrument.

Section snippets

Methods

THIS OBSERVATIONAL CROSS-SECTIONAL STUDY INCLUDED 166 eyes of 166 patients (88 glaucomatous patients and 78 healthy control subjects). Mean age (± SD) of glaucoma patients and healthy individuals was 68 ± 11 years and 65 ± 9 years, respectively (P = .09; Student’s t test). Subjects were evaluated at the Hamilton Glaucoma Center, University of California, San Diego, from April 2002 to January 2004. These patients were included in a prospective longitudinal study designed to evaluate optic nerve

RNFL thickness measurements

Table 1 shows mean values of Stratus OCT RNFL parameters in glaucomatous and normal eyes. After Bonferroni’s correction (α = 0.002; 25 comparisons), statistical significant differences were found for all parameters except thickness at 9-o’clock, Imax/Smax, Smax/Tavg, and Smax/Navg. Table 1 also shows ROC curve areas and sensitivities at fixed specificities. The 3 Stratus OCT RNFL parameters with largest areas under the ROC curves were inferior thickness (0.91), average thickness (0.91), and

Discussion

THE ANALYSIS OF STRATUS OCT SOFTWARE-PROVIDED PArameters showed that parapapillary RNFL measures and ONH topographic parameters had the highest power to discriminate glaucomatous from healthy eyes. Areas under the ROC curves and sensitivities at moderate and high specificities were similar for the best parameters from each of these two methods of analysis. We also found that a combination of selected RNFL and ONH parameters in a linear discriminant function resulted in further improvement of

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    Supported in part by the Foundation for Eye Research (F.A.M.) and NIH Grant EY11008 (L.M.Z.).

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