Diagnostic capability of optic nerve head rim width and retinal nerve fiber thickness in open-angle glaucoma

This study was performed to test the diagnostic capability of the minimum rim width compared to peripapillary retinal nerve fiber layer thickness in patients with glaucoma.

A case control, observer masked study, was conducted. Minimum rim width and retinal nerve fiber layer thickness were assessed using the patient-specific axis traced between fovea-to-Bruch's membrane opening center axis. For both minimum rim width and retinal nerve fiber layer thickness, the regionalization in six sectors (nasal, superior-nasal, superior-temporal, temporal, inferior-temporal, and inferior-nasal) was analyzed. Eyes with at least one sector with value below the 5% or 1% normative limit of the optical coherence tomography normative database were classified as glaucomatous. The area under the receiver operator characteristic curve, the accuracy, sensitivity, specificity, and predictive positive and negative values were calculated for both minimum rim width and retinal nerve fiber layer thickness.

A total of 118 eyes of 118 Caucasian subjects (80 eyes with open-angle glaucoma and 38 control eyes) were enrolled in the study. Accuracy, sensitivity, and specificity were 79.7%, 77.5%, and 84.2%, respectively, for minimum rim width and 84.7%, 82.5%, and 89.5% for retinal nerve fiber layer thickness. The positive predictive values were 0.91% and 0.94% for minimum rim width and retinal nerve fiber layer thickness, respectively, whereas the negative predictive values were 0.64% and 0.70%. The area under the receiver operator characteristic curve was 0.892 for minimum rim width and 0.938 for retinal nerve fiber layer thickness.

Our results indicated that the sector analysis based on Bruch's membrane opening and fovea to disk alignment is able to detect glaucomatous defects, and that Bruch's membrane opening minimum rim width and retinal nerve fiber layer thickness showed equivalent diagnostic ability.