Choroidal Thickness Correlates with Clinical and Imaging Metrics of Parkinson’s Disease: A Pilot Study

Article type: Research Article

Authors: Brown, Gregory L.^a | Camacci, Mona L.^b | Kim, Sean D.^b | Grillo, Stephanie^b | Nguyen, James V.^a | Brown, Douglas A.^c | Ullah, Sarah P.^d | Lewis, Mechelle M.^{a; e} | Du, Guangwei^a | Kong, Lan^f | Sundstrom, Jeffrey M.^b | Huang, Xuemei^{a; b; e; g; h; *} | Bowie, Esther M.^{b; *}

Affiliations: [a] Department of Neurology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA, USA | [b] Department of Ophthalmology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA, USA | [c] Department of Ophthalmology, Temple University-Lewis Katz School of Medicine, Philadelphia, PA, USA | [d] Department of Ophthalmology, Pittsburgh University School of Medicine, Pittsburgh, PA, USA | [e] Department of Pharmacology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA, USA | [f] Department of Public Health Sciences, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA, USA | [g] Department of Neurosurgery, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA, USA | [h] Department of Kinesiology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA, USA

Correspondence: [*] Correspondence to: Xuemei Huang, MD, PhD, Professor of Neurology, Penn State University-Milton S. Hershey Medical Center, H037, 500 University Dr, Hershey, PA 17033-0850, USA. Tel.: +1 717 531 0003/Ext:287082; Fax: +1 717 531 0266; E-mail: xuemei@psu.edu and Esther Bowie, MD, Associate Professor of Ophthalmology, Penn State University-Milton S. Hershey Medical Center, Suite 800, 500 University Dr, Hershey, PA 17033-0850, USA. Tel.: +1 717 531 5690; Fax: +1 717 531 5009; E-mail: ebowie@pennstatehealth.psu.edu.

Abstract: Background:Parkinson’s disease (PD) is marked clinically by motor symptoms and pathologically by Lewy bodies and dopamine neuron loss in the substantia nigra pars compacta (SNc). Higher iron accumulation, assessed by susceptibility MRI, also is observed as PD progresses. Recently, evidence has suggested that PD affects the retina. Objective:To better understand retinal alterations in PD and their association to clinical and SNc iron-related imaging metrics. Methods:Ten PD and 12 control participants (2 eyes each) from an ongoing PD imaging biomarker study underwent enhanced depth imaging optical coherence tomography evaluation. Choroidal (vascular) thickness and nerve layers were measured in 4 subregions [superior, temporal, inferior, and nasal] and at 3 foveal distances (1, 1.5, and 3 mm). These metrics were compared between PD and control groups. For significantly different metrics, their associations with clinical [levodopa equivalent daily dosage (LEDD), motor and visuospatial function] and SNc susceptibility MRI metrics [R2* and quantitative susceptibility mapping (QSM)] were explored. Results:Compared to control participants, PD participants had a thicker choroid (p = 0.005), but no changes in nerve layers. Higher mean choroidal thickness was associated with lower LEDD (p < 0.01) and better visuospatial function (p < 0.05). Subregion analyses revealed higher choroidal thickness correlated with lower LEDD and better motor and visuospatial measures. Higher mean choroidal thickness also was associated with lower nigral iron MRI (p < 0.05). Conclusion:A small cohort of PD research participants displayed higher choroidal thickness that was related to better clinical performance and less nigral pathology. These intriguing findings warrant further investigation.

Keywords: Choroid, optical coherence tomography, Parkinson’s disease, retina, susceptibility MRI, visuospatial function

DOI: 10.3233/JPD-212676

Journal: Journal of Parkinson's Disease, vol. 11, no. 4, pp. 1857-1868, 2021