Comparison of Retinal Nerve Fiber Layer Thickness Measured by Optical Coherence Tomography 2 Versus Optical Coherence Tomography 3 in Patients with Optic Nerve Head Drusen

Abstract

Abstract: : Purpose: Optical coherence tomography (OCT) is a valuable tool that is able to detect retinal nerve fiber layer (RNFL) thinning in eyes with optic nerve head drusen (ONHD). Original measurements were taken by OCT 2, which has been replaced by OCT 3. In this study, we compared the RNFL thickness and compared the variablity of the measurements using OCT 2 and OCT 3 in patients with ONHD. Methods: Ten eyes of five patients with ultrasound-proven bilateral ONHD and previous OCT 2 RNFL measurements were studied. We measured RNFL thickness (microns) in the superior, nasal, inferior, and temporal quadrants of both eyes of each subject using OCT 3. Summary statistics (mean and median) were calculated, and the IQR or measure of variablity was determined. Results: The average RNFL thickness was lower when measured by OCT 3 (72.1µm OD; 62.1µm OS) versus OCT 2 (79.4µm OD; 81.5µm OS). Overall, RNFL measurements taken with OCT 2 versus OCT 3 demonstrated high variability (see Table). Conclusions: This study, while employing a small number of subjects for hypothesis testing, demonstrates two trends: (1) RNFL thickness measured by OCT 3 is less than with OCT 2; and (2) there is great variability in the measurements between the two modalities. Therefore, RNFL thickness in ONHD patients measured by OCT 2 and OCT 3 cannot be compared for evidence of disease progression. IQR VALUES (MICRONS)  

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, S • drusen • optic disc