Objective: Our aim is to evaluate the structural changes in retina and choroid by Optical Coherence Tomography (OCT) in idiopathic Parkinson’s disease (PD) and common autosomal recessive forms of PD due to parkin, PINK1, DJ1 mutations.

Background: OCT findings in PD are controversial in the literature, both neurodegenerative dopaminergic cell loss and alpha-synuclein pathology are blamed to be responsible from the structural retinal changes. There is no data related to autosomal recessive PD, where alpha-synuclein pathology is limited or scarcely observed.

Methods: PD patients; mutation positive (MP) (n=15; 13 parkin, 1 PINK1 and 1 DJ-1), mutation negative (MN) (n=35) and 50 age-, and sex-matched controls were enrolled in the study. Spectral Domain OCT images above quality index of 25 were included in the study. The subfoveal choroidal thickness (ChT), Retinal Nerve Fiber Layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL) and outer plexiform and outer nuclear (OPL-ONL) layers were assessed and were compared in between MP, MN and control groups.

Results: The mean ages were 54.66 ± 12.96 y (29-78) and 55.10 ± 12.18 years (31-80) in PD and control groups, respectively. Age at disease onset was younger (29.9 vs 52.3), mean disease duration was longer (15.6 vs 7 years) and L-DOPA equivalent dose was lower (605 vs 800 mg) in MP compared to MN group, whereas Hoehn-Yahr stages were similar (1.6 vs 1.8). There wasn’t any significant difference between MP and MN groups, for any of the OCT parameters. The mean ChT was 267.9 ± 62.5 in PD and 235.5 ± 69.8 μm in control group (p<0.05). The mean RNFL and GCL thicknesses were 12.94 ± 2.07, 15.14 ± 4.16 μm and 13.68 ± 2.34, 16.78 ± 5.48 μm in PD and controls, respectively (p<0.05). The mean IPL and INL thicknesses were 20.32 ± 4.18, 20.36 ± 3.89 μm and 20.7 ± 5.04, 21.08 ± 6.60 μm in PD and control group (p=0.48, p=0.37) The mean OPL and ONL thicknesses were similar, 25.36 ± 6.28 vs 25.40 ± 8.02 μm and 86.04 ± 10.9 vs 86.50 ± 14.63 μm in PD and control group.

Conclusions: RNFL and GCL thinning may occur due to the neurodegenerative process in PD and retina is affected similarly in the autosomal recessive PD forms. Thus, overt alpha-synuclein pathology may not be responsible from retinal involvement of PD. The finding that the choroid being thicker in PD necessitates further investigation for possible relation with PD pathogenetic process.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/retinal-and-choroidal-changes-in-autosomal-recessive-pd-are-similar-to-idiopathic-pd/