Effect of the Eye Tracking System on the Reproducibility of Measurements Obtained with Spectral-domain Optical Coherence Tomography in Glaucoma

Purpose: The purpose of this study was to evaluate whether the eye tracking system (ETS) improved the reproducibility of a single circle peripapillary retinal nerve fiber layer (RNFL) measurement acquired with spectral-domain optical coherence tomography (OCT). Materials and Methods: The sample comprised 205 individuals divided into 2 groups according to intraocular pressure and visual field outcomes. A total of 100 healthy individuals and 105 patients with open-angle glaucoma underwent imaging of the optic nerve head with OCT 3 times during the same session and 2 additional times in subsequent sessions (30 days apart). Intraclass correlation coefficient (ICC), coefficient of variation, and test-retest variability were calculated for the RNFL thickness acquired with and without the ETS enabled, and compared. Results: The glaucoma group mainly comprised patients with moderate glaucoma (mean deviation of standard automated perimetry,-6.73±6.2 dB). The RNFL thicknesses did not differ between acquisitions with or without the ETS activated and disabled. All ICCs were >0.9 in the control and glaucoma groups with or without the ETS activated. The best parameter in the intersession analysis (with ETS activated) was global RNFL thickness (ICC, 0.95; coefficient of variation, 2.7%; and test-retest variability, 2.87 μm). The reproducibility and repeatability of RNFL measurements did not differ significantly between acquisitions with or without the ETS in either group. Conclusions: The reproducibility of peripapillary RNFL thicknesses acquired with OCT was excellent. The variability between OCT measurements did not decrease with the ETS activated.