Mapping trans-synaptic degeneration in the optic radiations in glaucoma

a diffusion mri study

Yuyi You, Chenyu Wang, Stuart Graham, Sukanya Arunachalam, Megha Kaushik, Brian Chua, Alexander Klistorner

Research output: Contribution to journalMeeting abstract

Abstract

Aims: To investigate trans-synaptic changes in the optic radiations (OR) in glaucoma patients by using diffusion MRI scans and multifocal visual evoked potentials (mfVEP) recordings.
Methods: Seventeen primary open angle glaucoma (POAG) patients and 13 age- and sex-matched controls were enrolled. All glaucoma patients had predominantly either superior or inferior binocular symmetrical visual field defects with the presence of corresponding retinal nerve fibre layer (RNFL) loss. All study participants underwent MRI brain scans, including axial T1-weighted imaging, FLAIR sequence and diffusion-weighted imaging. MfVEPs were also recorded for all the patients. Diffusion MRI indices including axial diffusivity (AD), radial diffusivity (RD), fractional anisotropy (FA) and mean diffusivity (MD) as well as mfVEP parameters (latency and amplitude) were analysed.
Results: There was a significant increase in AD and RD measurements in the OR of glaucoma patients, which was found to be topographically associated with visual hemifield loss. AD and RD up-regulation was observed along the entire length of the part of OR carrying fibres projecting to the affected visual field (AD = 1.43 ± 0.11; RD = 0.62 ± 0.06) compared with normal controls (AD = 1.40 ± 0.11; RD = 0.59 ± 0.05; p<0.05), but only in the proximal section (close to the LGN) of the part of OR that carries fibres projecting to the unaffected visual field. Further, there was a significant correlation between RD and mfVEP latency (r = 0.574; p = 0.002).
Conclusion: Axonal loss (measured by AD) was observed in the OR of glaucoma patients, which was topographically correlated with visual field defects/ RNFL loss. VEP latency analysis suggests that demyelination may play a role in trans-synaptic degeneration
Original languageEnglish
Article number55
Pages (from-to)102-103
Number of pages2
JournalClinical and Experimental Ophthalmology
Volume44
Issue numberS1
Publication statusPublished - Nov 2016
EventAnnual Scientific Congress of the Royal Australian and New Zealand College of Ophthalmologists (48th : 2016) - Melbourne, Australia
Duration: 19 Nov 201623 Nov 2016

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