Optical Coherence Tomography for Neurodegeneration

Optical coherence tomography examination was performed using a SD-OCT (Spectralis, Heidelberg Engineering, Heidelberg, Germany) with automatic real-time (ART) function for image averaging. Data are reported for peripapillary retinal nerve fiber layer thickness (pRNFL) to assess axonal degeneration. Total macular volume (TMV), volumes of combined ganglion cell and inner plexiform layer (GCIPL = GCL + IPL), and inner retinal layer (IRL = GCL + IPL + mRNFL) were assessed as markers for neuronal degeneration. Data for inner nuclear layer (INL) were evaluated to detect edema-related retinal changes. Calculation of macular layers is given for a 3 mm diameter cylinder around the fovea from a macular volume scan (20° × 20°, 25 vertical B-scans, ART ≤ 49). The pRNFL was measured with an activated eye tracker using 3.4 mm ring scans around the optic nerve (12°, 1,536 A-scans, ART ≤ 100). Segmentation of all the layers was performed semi-automatically using software provided by the OCT manufacturer (Eye Explorer 1.9.10.0 with viewing module 6.3.4.0, Heidelberg Engineering, Heidelberg, Germany). All the scans were checked for sufficient quality and segmentation errors and corrected, if necessary. OCT data are reported according to the APOSTEL and OSCAR-Ib recommendations (47 (link)–49 (link)). Data were analyzed separately for the patients up to 17 years of age and adults.