Imaging of the Retinal Nerve Fibre Layer with Spectral-domain Optical Coherence Tomography in Patients with Glaucoma

Abstract

Evaluation of the retinal nerve fibre layer (RNFL) is key to diagnosing and monitoring changes in glaucoma. Optical coherence tomography (OCT) is a non-invasive, objective, quantitative method that provides realtimein vivoimages of the retina. The new spectral-domain OCTs have increased resolution and acquisition speed compared with earlier time-domain OCTs, enabling the generation of highly detailed 3D images. Axial resolution has also been improved from 10 to 3–5μm. Thus, spectral-domain OCT is a promising new clinical tool for evaluating the RNFL in glaucoma and other retinal diseases. Recent studies report that spectral-domain OCT provides peri-papillary RNFL measurements with excellent repeatability and reproducibility. The reduced variability compared with time-domain OCT may improve detection of disease progression in glaucoma patients. In cross-sectional studies, most authors suggest that the two OCT systems have similar diagnostic potential to discriminate between healthy and glaucoma patients. Nevertheless, the Cirrus HD-OCT (spectral-domain) tends to yield a slightly higher sensitivity at fixed specificities than the Stratus OCT (time-domain) for glaucoma diagnosis. In healthy subjects and patients with glaucoma, RNFL thickness measurements acquired with the two OCT systems correlated well, but their values cannot be used interchangeably.