Objective: The aim of this study was to find retinal pathology in Parkinson’s disease (PD) via Optical Coherence Tomography (OCT) that deteriorates over time, as an expression of the neurodegenerative process.

Background: OCT is a non-invasive method to detect structural retinal changes in PD as described in many studies. However, the suitability of this method as a technical marker or progression marker is discussed controversial, i.e. due to the lack of longitudinal studies.  This study is characterized by a particularly large time interval between the first and second measurement of 73 months.

Method: HD-OCT ®Heidelberg- Engineering and ®Spectralis was used. Average thickness of the retina and retinal single layer volumes in 12 PD patients were examined in a longitudinal setting at two timepoints. The average and standard deviation of the total volume (mm³) of each layer (retinal nerve fibre layer=RNFL, ganglion cell + inner plexiform layer=GCL + IPL, inner nuclear layer=INL, outer plexiform layer=OPL, outer nuclear layer=ONL) was calculated. Statistical analyses were performed using one-way analysis of variance.

Results: There was a reduction of the retinal layer volume of RNFL (0.94 mm³ vs 0.90 mm³) ,GCL+IPL (0.95 mm³ vs 0.93 mm³), and the whole retinal thickness (4.76 mm³ vs 4.71 mm³) between measurements 1 and 2. Hence none of these reductions was statistically significant.

Conclusion: Retinal changes in PD as a result of retinal dopaminergic loss are well known in PD. However, the study situation regarding the progression of these changes over the course of the disease is limited. We were able to show a thinning of retinal layers over time, but these changes were small and not statistically significant despite the large time interval between measurements. On the one hand, this may be due to the small group of patients, but it could also indicate that retinal dopaminergic pathology is not subject to the same disease progression as is known for motor decline, hence it could be that retinal pathology also reflects a non dopaminergic mechanism in PD pathology as it is most probably the case with olfactory dysfunction.

This abstract has been presented as a poster at the “German Neurological Society Congress (DGN)” in Stuttgart, September 27, 2019.

References: 1. Schneider M, Müller H-P, Lauda F, Tumani H, Ludolph AC, Kassubek J, et al. Retinal single-layer analysis in Parkinsonian syndromes: an optical coherence tomography study. J Neural Transm. 2014;121: 41–47. Available: http://link.springer.com/10.1007/s00702-013-1072-3

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MDS Abstracts - https://www.mdsabstracts.org/abstract/retinal-pathology-in-parkinsons-disease-a-longitudinal-study-with-optical-coherence-tomography/