Modeling Neurodegeneration in Patients with Visual Pathway Tumors by Retinal Optical Coherence Tomography

Assessment the neurodegenaration process of post-geniculate optic pathway in thalamic tumors using optical coherence tomography: Post-geniculate optic pathway in thalamic tumors

PURPOSE

To investigate the effect of thalamic tumors related to post-geniculate optic pathway and those of microsurgical removal on neurodegeneration process of visual pathway using OCT.

METHODS

This cross-sectional study included 30 eyes of 15 patients with thalamic tumors and data compiled from 45 eyes of 45 healthy participants. The analysis of variables was divided into ipsilateral and contralateral eye depends on the laterality of brain tumors. The data gained at baseline, postoperative 3rd and postoperative 6th month period was analyzed in One-Way Repeated Measures ANOVA.

RESULTS

The mean superior quadrant retinal nerve fiber layer (RNFL) thickness of ipsilateral eye was significantly thicker (p = 0.02), while inferior hemifield ganglion cell-inner plexiform layer (GC-IPL) thickness of contralateral eye was significantly higher compared to control groups (p = 0.02). Significant negative correlations were found between the mean preop. mean deviation (MD) and tumor volume and time interval between initial diagnosis and surgery (r = - 0.730, p = 0.002 and r = - 0.680, p = 0.005, respectively) in the ipsilateral eye. In repeated measure analysis, there was no unfavourable effect of thalamic microsurgery on peripapillary average RNFL thickness on both ipsilateral and contralateral eyes (Ipsilateral eye; f (1.5,21.7) 0.76 p = 0.51 and contralateral eye; f (1.4,20.4) 0.42 p = 0.59).

CONCLUSION

This study suggests that thalamic tumors affecting post-geniculate optic pathway may lead to significant increase in RNFL and GC-IPL thicknesses and changes in VF parameters. Timely intervention in thalamic tumors may prevent irreversible loss of retinal axons secondary to neurodegeneration process.

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

AIM

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.

METHODS

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.

RESULTS

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).

CONCLUSION

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.