How do intracranial tumors associated with visual pathways affect quadrant and sectoral based optical coherence tomography measurements: The effect of intracranial tumors on RNFL and GC-IPL thickness.

Abstract

To investigate the quantitative sectoral and regional changes of retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GC-IPL) thickness in different types of intracranial tumors associated with visual pathways. This comparative retrospective study included 58 eyes of 30 patients with intracranial tumors and the data of 62 eyes of 31 healthy subjects. The RNFL and GCIPL thicknesses were analyzed using spectral-domain optical coherence tomography (OCT). The tumors were classified into ones that affect pre-geniculate and post-geniculate pathway. The mean RNFL thickness in temporal quadrant was significantly thinner in eyes with intracranial tumors affecting the pre-geniculate optic pathway compared to controls (p = 0.04). In contrast, the mean superior quadrant RNFL thickness was significantly thicker in eyes with brain tumors associated with post-geniculate optic pathway (p = 0.01). The mean GC-IPL thicknesses of the inner ring superotemporal, superonasal, inferotemporal and inferionasal sectors and outer ring superonasal and inferonasal sectors were significantly thinner in eyes with intracranial tumors affecting the pre-geniculate optic pathway compared to control eyes (p = 0.02, p = 0.001, p = 0.02, p = 0.003, p = 0.008 and p = 0.03 respectively). The results of this study showed that significant changes can be seen in the different RNFL quadrants and GC-IPL sectors in eyes with intracranial tumors affecting pre-geniculate or post-geniculate optic pathway. OCT is a very useful imaging technique to quantify these structural changes which take place during the neurodegeneration process of visual pathways in intracranial tumors.