title: Evaluation of Retinal Vessel Morphology in Patients with Parkinson's Disease Using Optical Coherence Tomography.
abstract: OBJECTIVE
  The retina has been found affected in Parkinson's disease (PD). It is unclear if this is due to neurodegeneration of local dopamine-dependent retinal cells, a result of central nervous degeneration including the optic nerve or retinal small vessel disease. This study aimed to detect changes of the retinal vasculature in PD patients compared to controls.
  
  
  METHODS
  We examined 49 PD patients and 49 age- and sex-matched healthy controls by spectral domain optical coherence tomography (SD-OCT) with a circular scan centred at the optic disc. Vessels within the retinal nerve fibre layer were identified by an automated algorithm and thereafter manually labelled as artery or vein. Layer segmentation, vessel lumen and direct surrounding tissue were marked automatically with a grey value and the contrast between both values in relation to the surrounding tissue was calculated. The differences in these grey value ratios among subjects were determined and used as an indicator for differences in vessel morphology. Furthermore, the diameters of the veins and arteries were measured and then compared between the groups.
  
  
  RESULTS
  The contrast of retinal veins was significantly lower in PD patients compared to controls, which indicates changes in vessel morphology in PD. The contrast of arteries was not significantly different. Disease duration, disease stage according to Hoehn and Yahr or age did not influence the grey value ratios in PD patients. Vessel diameter in either veins or arteries did not differ between subject groups. The contrast of retinal veins contralateral to the clinically predominant and first affected side was significantly lower compared to the ipsilateral side.
  
  
  CONCLUSIONS
  Our data show a potential difference of the retinal vasculature in PD patients compared to controls. Vascular changes in the retina of PD patients might contribute to vision-related complaints in PD.
authors.affiliation: Department of Ophthalmology, Hamburg Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Robert
authors.identifier: http://orcid.org/0000-0002-5986-5047
authors.initials: R
authors.lastname: Kromer
authors.affiliation: Department of Neurology, Hamburg Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Buhmann
authors.affiliation: Department of Neurology, Hamburg Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Ute
authors.initials: U
authors.lastname: Hidding
authors.affiliation: Department of Ophthalmology, Hamburg Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Keserü
authors.affiliation: Department of Ophthalmology, Hamburg Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Diana
authors.initials: D
authors.lastname: Keserü
authors.affiliation: Department of Ophthalmology, Hamburg Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Hassenstein
authors.affiliation: Department of Ophthalmology, Hamburg Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Birthe
authors.initials: B
authors.lastname: Stemplewitz
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D012171:Retinal Vessels / Q000000981:diagnostic imaging* / Q000473:pathology*; D041623:Tomography, Optical Coherence