advertisement
Editors Selection IGR 16-3
Anatomical structures: Retrochiasmal optic pathways
Comment by Ahmed El-Rafei on:
58936 A topographical relationship between visual field defects and optic radiation changes in glaucoma, Kaushik M; Graham SL; Wang C et al., Investigative Ophthalmology and Visual Science, 2014; 55: 5770-5775
Recent advancements in diffusion tensor imaging has enabled the reconstruction and characterization of the brain white matter fibers. This imaging technique has been utilized to segment and to evaluate the visual pathway in different pathologies. The study by Kaushik et al. used diffusion tensor imaging to investigate the secondary effects of primary open angle glaucoma on the optic radiations (OR). Reduction in OR size and fractional anisotropy, in addition to elevated radial and mean diffusivities, are reported in this paper as consequences of glaucoma. These results are in agreement with recent studies suggesting that the integrity of OR fibers are compromised in the presence of glaucoma. Moreover, this study differentiates the glaucoma induced OR changes corresponding to retinal hemifields with and without visual defects. A significant rarefaction of the OR associated with the affected hemifields in comparison to unaffected hemifields was shown. Nevertheless, no significant difference was observed in DTI-derived measures between affected and unaffected ORs.
The findings of this study add to the growing evidence from recent studies suggesting the trans-synaptic nature of degeneration caused by glaucoma
The findings of this study add to the growing evidence from recent studies suggesting the trans-synaptic nature of degeneration caused by glaucoma. The authors suggested a possible explanation for the retained fiber bundles in the unaffected OR in that it may be due prolonged loss of the axons projected from the retinal ganglion cells. This hypothesis, if confirmed, could be extremely important for the potential preservation of the cerebral fiber tracts of the visual pathway by neuroprotective agents. However, it needs further investigation by performing a comprehensive study that includes large number of subjects, reliability analysis for identifying OR, and higher DTI-image resolution. In addition, this study demonstrated that DTI-indices show similar sensitivity to severe and early glaucoma damage from affected and unaffected hemifields, respectively. Therefore, DTI-metrics could provide an additional mean to early detect glaucoma
Comments
The comment section on the IGR website is restricted to WGA#One members only. Please log-in through your WGA#One account to continue.Log-in through WGA#One