Abstract
Introduction: :
P Jindahra1, A Petrie2, G T Plant11Neuro-opthalmology, The National Hospital for Neurology and Neurosurgery, Queen square, London, U.K. 2Eastman dental hospital, Grays Inn Road, London, UK
Purpose: :
To study the time course of trans-synaptic retrograde degeneration following post-geniculate injury.
Methods: :
(1) 26 patients were recruited who had suffered acute unilateral damage to the post-geniculate visual pathway at a known time in the past (range 0.12-50 years) together with age and sex matched control subjects. Peri-papillary retinal nerve fibre layer (RNFL) thickness was measured on a single occasion (mean of the two eyes). Version 4 StratusOCT, Carl Zeiss Meditec was used. (2) 7 of the 26 patients and a further 4 patients with incomplete hemianopia were recruited within 5 months of the injury (range 5 - 177 days). In this group the RNFL thickness was measured serially for at least 43 days (range 43- 876 days; minimum of 3 measurements) to study the rate of change. Each case underwent magnetic resonance imaging of the brain and Humphrey automated perimetry.
Results: :
(1) There is a negative correlation between the RNFL thickness and time since onset of injury (n = 26; R2 = 0.2; p = 0.03). This equates to a reduction in RNFL thickness of 0.42 microns per year. This compares with estimates of 0.2 microns per year in normal ageing. (2) In 3/7 patients with hemianopia the RNFL thickness began to decrease within three months of the acute event and there is a trend to decline further over a year. In patients with either homonymous quadrantanopia or scotoma no change in the RNFL thickness has been detected using this technique.
Conclusions: :
We have shown previously that retrograde trans-synaptic degeneration can be detected using OCT. The time course of this can be followed and may be useful as a model of trans-synaptic retrograde degeneration in the human brain.
Keywords: nerve fiber layer • neuro-ophthalmology: cortical function/rehabilitation • visual cortex