The objective of the study is to quantify the rate of trans-synaptic retrograde degeneration (TSRD) following post-chiasmal damage. We have shown previously that TSRD can be detected in the retina by using optical coherence tomography (OCT) and in the optic tract using MRI.
Method (1) 38 patients were recruited following acute unilateral damage to the post-geniculate visual pathway (onset 0.016–67 years prior to testing) together with age and sex matched controls. Peri-papillary retinal nerve fibre layer (RNFL) thickness was measured with OCT on a single occasion. (2) 7 cases with homonymous hemianopia and 4 cases with smaller visual field defects were recruited within 4 months of the stroke (range 5–112 days). In this group the RNFL thickness was measured serially for at least 172 days (range 172–917 days). Linear regression was used in the statistical analysis.
Results (1) There is a negative correlation between the RNFL thickness and log time since onset of injury (n=38, r=0.54; p<0.001). (2) 6/7 of patients with homonymous hemianopia the RNFL thickness began to decrease within 5–6 months of the acute event and there is a trend to decline further over a year. In patients with homonymous quadrantanopia or scotoma no RNFL loss has been identified except for a case with an infarct at the lateral geniculate body.
Conclusion The time course of TSRD can be followed by utilising OCT.