Large diameter optic nerve axon fibres in Alzheimer's disease

Syed, Anila B.; Armstrong, Richard A. and Smith, Christopher U.M. (1992). Large diameter optic nerve axon fibres in Alzheimer's disease. IN: Meeting of the Society for Experimental Optometry. 1992-07-01. (Unpublished)

Abstract

A variety of visual symptoms have been associated with Alzheimer's disease (AD). These include delays in flash visual evoked potentials which indicate a disruption of the integrity of the visual pathway. Examination of the visual cortex has revealed the presence of both senile plaques and neurofibrillary tangles. The purpose of this study was to determine whether there were differences in the number and/or size of optic nerve axons between AD patients and non-demented age-matched controls. Five optic nerves from AD patients and five from age-matched controls were embedded in epon resin and 1 micron sections prepared on a Reichert ultramicrotome. The sections were then stained in toluidine blue and examined at x400 magnification. The numbers of axons were counted in photographs of three fields taken at random from each section. To evaluate the axon diameters, 70 axons were chosen at random from each patient and measured using a calibrated eyepiece graticule. The total axon counts revealed no significant differences between the AD optic nerves and the age-matched controls. However, the frequency distribution of axon diameters was significantly different in the two groups. In particular, there were fewer larger diameter axons in patients with AD as previously reported. Degeneration of the large diameter axons suggests involvement of the magnocellular as opposed to the parvocellular pathways. Hence, there could be differences in visual performance of AD patients compared with normals which could be important in clinical diagnosis.

Divisions: Life & Health Sciences > Optometry
Life & Health Sciences > Ophthalmic Research Group
Life & Health Sciences > Health Sciences
Life & Health Sciences > Neurosciences research group
Additional Information: Abstract appearing in Papers presented at the meeting of The Society for Experimental Optometry, in Birmingham (UK), on 27–28 July 1992, Ophthal Physiol Opt 13:104, 0275-5408.
Event Title: Meeting of the Society for Experimental Optometry
Event Type: Other
Event Dates: 1992-07-01
Uncontrolled Keywords: visual symptoms,Alzheimer's disease,flash visual evoked potentials,integrity,visual pathway,visual cortex,senile plaques,neurofibrillary tangles,optic nerve axons,diagnosis
Published Date: 1992

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