Objective: Visual disturbances are a common non-motor symptom of Parkinson’s Disease (PD) though this is not often intuitive to many providers caring for PD patients.  We examine whether visual systems in PD patients were affected to a level in which night vision might be significantly impaired and warrant regular screening.

Background: Anosmia, REM Behavior Disorder, and constipation have been understood to likely precede the onset of motor symptoms by years, possibly decades.  Autonomic disorders are noted to affect PD patients early including autonomic control of pupillary function.  Lewy bodies, neurofibrillary degeneration and neuronal loss have been reported in the Edinger-Westphal nucleus (1) and deficiency of the dopaminergic amacrine cells (2) is understood to contribute  to deficits in visual acuity, contrast and color in PD.

Method: The Non-Motor Rating Scale (MDS-NMS) was revised in 2019 by the International Parkinson and Movement Disorder Society with questions surveying 51 items including mood and cognition, urinary, sexual, sleep, pain and others but does not query vision.  The previous iteration, the Non-Motor Symptoms Questionnaire (NMSQ) created in 2004 reviewed 30 questions with one addressed to the visual system specifically (diplopia).

Results: In our clinic, we ask patients specifically about visual symptoms since it is not included in the MDS-NMS.  Questioning specifically about night blindness and then driving at night can lead to an avenue for discussion of awareness and safety.  It was recently reported that visual defects and retinal abnormalities are present in the majority of PD patients such that biomarkers for retinal dysfunction may soon become a non-invasive test for Parkinson’s Disease (3).

Conclusion: Night vision blindness is often present in PD patients and should be queried and addressed in the clinic. Studies are suggesting this may be a rare opportunity to screen for early Parkinson’s symptoms as dopamine is involved in retinal function and the ANS is involved with pupillary function.

References: 1. Hori, N, et al. Pupillary supersensitivity and visual disturbance in Parkinson’s disease. Clinical Autonomic Research (2008) 18:20-27. 2. Weil, Rimona S., et al. Visual dysfunction in Parkinson’s disease. Brain (2016) Nov; 139(11):2827-2843. 3. Indrieri, Alessia, et al. Dopamine, Alpha-Synuclein, and Mitochondrial Dysfunctions in Parkinsonian Eyes. Frontiers in Neuroscience (2020) 14:567129.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/night-vision-blindness-should-be-discussed-with-our-parkinsons-disease-patients-sooner-rather-than-later/