Objective: We assessed the role of visual measures and retinal volume (in dopaminergic layers: ganglion cell layer (GCL) and inner plexiform layer (IPL)) to predict risk of Parkinson’s disease (PD) dementia.

Background: Dementia is a common and devastating effect of PD. Identifying quantitative measures to detect and track cognitive change is important for trials to prevent Parkinson’s dementia.

Method: In this cohort study we collected visual, cognitive and motor data in patients with PD. Participants underwent ophthalmic examination, retinal imaging using optical coherence tomography (OCT), and visual assessment including acuity and contrast sensitivity and high-level visuo-perception measures of skew-tolerance and biological motion. Detailed neuropsychology and assessment of PD were also performed. We assessed risk of PD dementia using a recently described algorithm that combines age at onset, gender, depression, motor scores and baseline cognition. Researchers performing OCT analysis were blinded to dementia risk scores. We compared visual measures in PD with controls, and PD patients at high- versus low-risk of dementia. We also correlated risk of dementia with clinical and visual measures.

Results: 112 patients with PD and 35 unaffected controls were included in the study. Mean disease duration was 4.1 (±2.5) years. None of these patients had dementia. Poorer performance in visual measures was associated with higher risk of dementia (acuity: R2=0.14, p<0.0001; contrast sensitivity: R2=.27, p<0.0001; skew tolerance: R2 = 0.16, p<0.0001 and biological motion: R2=0.18, p<0.0001).  Retinal structure, measured as GCL and IPL thinning were associated with higher risk of PD dementia (R2=0.11, p=0.00063, R2 = 0.12, p=0.00029). These relationships were not seen for the retinal nerve fibre layer that does not contain dopaminergic cells and were not seen in unaffected controls.

Conclusion: Our findings suggest that visual measures and retinal GCL and IPL volumes may be useful to predict risk of developing dementia in PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/visual-dysfunction-and-retinal-thinning-predict-dementia-risk-in-parkinsons-disease/