Self-Reported Visual Complaints in People with Parkinson's Disease: A Systematic Review

[Retinal OCT biomarkers and neurodegenerative diseases of the central nervous system beyond Alzheimer's disease]

BACKGROUND

Optical coherence tomography (OCT) biomarkers are increasingly used by neurologists, psychiatrists, and ophthalmologists for the diagnosis, prognosis, and follow-up of neurodegenerative diseases. Long-term data on OCT biomarkers of selected primary and secondary neurodegenerative diseases of the central nervous system (CNS), such as multiple sclerosis (MS) or Parkinson's disease, are already available in part. In addition, there are rare neurodegenerative diseases with early disease onset that may show OCT abnormalities.

METHODS

A literature review on the association of OCT biomarkers with neurodegenerative diseases of the CNS beyond Alzheimer's disease is presented. Parkinson's disease, MS, Friedreich's ataxia, Huntington's disease, spinocerebellar ataxia, and lysosomal storage diseases are addressed.

RESULTS

Relevant OCT biomarkers of neurodegenerative diseases are the macular ganglion cell inner plexiform layer (GCIPL) and the peripapillary retinal nerve fiber layer (pRNFL) thickness. Different sectors may be affected depending on the disease entity in addition to global pRFNL reduction. OCT‑angiography (OCT-A) is also increasingly used as a biomarker in neurodegenerative diseases.

CONCLUSION

Optical coherence tomography biomarkers are used in an interdisciplinary context. Retinal pathologies should be excluded by an ophthalmologist. While OCT biomarkers are increasingly used clinically in MS, the benefit in other neurodegenerative diseases, especially the rare ones, is less well documented. Further longitudinal studies are required.

Susceptibility to geometrical visual illusions in Parkinson's disorder

Parkinson's disorder (PD) is a common neurodegenerative disorder affecting approximately 1-3% of the population aged 60 years and older. In addition to motor difficulties, PD is also marked by visual disturbances, including depth perception, abnormalities in basal ganglia functioning, and dopamine deficiency. Reduced ability to perceive depth has been linked to an increased risk of falling in this population. The purpose of this paper was to determine whether disturbances in PD patients' visual processing manifest through atypical performance on visual illusion (VI) tasks. This insight will advance understanding of high-level perception in PD, as well as indicate the role of dopamine deficiency and basal ganglia pathophysiology in VIs susceptibility. Groups of 28 PD patients (Mage = 63.46, SD = 7.55) and 28 neurotypical controls (Mage = 63.18, SD = 9.39) matched on age, general cognitive abilities (memory, numeracy, attention, language), and mood responded to Ebbinghaus, Ponzo, and Müller-Lyer illusions in a computer-based task. Our results revealed no reliable differences in VI susceptibility between PD and neurotypical groups. In the early- to mid-stage of PD, abnormalities of the basal ganglia and dopamine deficiency are unlikely to be involved in top-down processing or depth perception, which are both thought to be related to VI susceptibility. Furthermore, depth-related issues experienced by PD patients (e.g., increased risk for falling) may not be subserved by the same cognitive mechanisms as VIs. Further research is needed to investigate if more explicit presentations of illusory depth are affected in PD, which might help to understand the depth processing deficits in PD.

Widening the Spectrum of Risk Factors, Comorbidities, and Prodromal Features of Parkinson Disease

Importance

The prodromal phase of Parkinson disease (PD) may last for more than 10 years. Recognition of the spectrum and occurrence of risk factors, comorbidities, and prodromal features of PD can increase understanding of the causes and development of the disease and help identify individuals at risk.

Objective

To identify the association of a subsequent diagnosis of PD with a range of risk factors and prodromal features, including lifestyle factors, comorbidities, and potential extracerebral manifestations of PD.

Design, Setting, and Participants

This was a case-control study using insurance claims of outpatient consultations of patients with German statutory health insurance between January 1, 2011, and December 31, 2020. Included were patients with incident diagnosis of PD without a previous diagnosis of parkinsonism or dementia and controls matched 1:2 for age, sex, region, and earliest year of outpatient encounter.

Exposures

Exposures were selected based on previous systematic reviews, case-control and cohort studies reporting on risk factors, comorbidities, and prodromal features of PD.

Main Outcomes and Measures

Previously postulated risk factors and prodromal features of PD, using the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) coding.

Results

A total of 138 345 patients with incident PD (mean [SD] age, 75.1 [9.8] years; 73 720 male [53.3%]) and 276 690 matched controls (mean [SD] age, 75.1 (9.8) years; 147 440 male [53.3%]) were identified. Study participants were followed up for a mean (SD) of 6.0 (2.0) years. Consistent with previous reports, risk factors and prodromal features associated with PD included traumatic brain injury, odds ratio (OR), 1.62; 95% CI, 1.36-1.92; alcohol misuse, OR, 1.32; 95% CI, 1.21-1.44; hypertension, OR, 1.29; 95% CI, 1.26-1.31; anosmia, OR, 2.16; 95% CI, 1.59-2.93; and parasomnias (including RBD), OR, 1.62; 95% CI, 1.42-1.84. In addition, there were associations with restless legs syndrome (OR, 4.19; 95% CI, 3.91-4.50), sleep apnea (OR, 1.45; 95% CI, 1.37-1.54), epilepsy (OR, 2.26; 95% CI, 2.07-2.46), migraine (OR, 1.21; 95% CI, 1.12-1.29), bipolar disorder (OR, 3.81; 95% CI, 3.11-4.67), and schizophrenia (OR, 4.48; 95% CI, 3.82-5.25). The following diagnoses were also found to be associated with PD: sensory impairments beyond anosmia, such as hearing loss (OR, 1.14; 95% CI, 1.09-1.20) and changes of skin sensation (OR, 1.31; 95% CI, 1.21-1.43). There were also positive associations with skin disorders (eg, seborrheic dermatitis, OR, 1.30; 95% CI, 1.15-1.46; psoriasis, OR, 1.13; 95% CI, 1.05-1.21), gastrointestinal disorders (eg, gastroesophageal reflux, OR, 1.29; 95% CI, 1.25-1.33; gastritis, OR, 1.28; 95% CI, 1.24-1.33), conditions with a potential inflammatory component (eg, seronegative osteoarthritis, OR, 1.21; 95% CI, 1.03-1.43), and diabetes types 1 (OR, 1.32; 95% CI, 1.21-1.43) and 2 (OR, 1.24; 95% CI, 1.20-1.27). Associations even 5 to 10 years before diagnosis included tremor (odds ratio [OR], 4.49; 95% CI, 3.98-5.06), restless legs syndrome (OR, 3.73; 95% CI, 3.39-4.09), bipolar disorder (OR, 3.80; 95% CI, 2.82-5.14), and schizophrenia (OR, 4.00; 95% CI, 3.31-4.85).

Conclusions and Relevance

Results of this case-control study suggest that the associations found between PD and certain risk factors, comorbidities, and prodromal symptoms in a representative population may reflect possible early extrastriatal and extracerebral pathology of PD. This may be due to shared genetic risk with PD, medication exposure, or direct causation, or represent pathophysiologically relevant factors contributing to the pathogenesis of PD.

Reading Difficulties in Parkinson's Disease: A Stepped Care Model for Neurovisual Rehabilitation

BACKGROUND

People with Parkinson's disease (PD) frequently experience reading difficulties. Little is known about what functional impairments distinguish people with PD with and without reading difficulties and how these should guide rehabilitation.

OBJECTIVE

To provide concrete advice for an efficient stepped care model for reading difficulties in PD, based on extensive functional assessments.

METHODS

This study included 74 people with PD in a neurovisual rehabilitation setting who underwent assessment of visual, visuoperceptual, and cognitive functions. Outcomes were compared between those with frequent (RD+; N = 55) and infrequent reading difficulties (RD-; N = 19). Aids and advice provided during rehabilitation were registered.

RESULTS

Only a few functions appeared to distinguish RD+ and RD-. Visual functions (i.e., contrast sensitivity, g = 0.76; reading acuity, g = 0.66; visual acuity, g = 0.54) and visuoperceptual functions (i.e., visual attention, g = 0.58, visual motor speed, g = 0.56) showed significant worse scores in RD+ compared to RD-. Aids and advice applied consisted mainly of optimizing refraction, improving lighting, and optimizing text size and spacing.

CONCLUSION

The test battery showed significant differences between RD+ and RD-on only a few tests on visual and visuoperceptual functions. The applied aids and advice matched well with these impairments. Therefore, we recommend a stepped care model, starting with a short test battery on these functions. If this battery indicates functional impairments, this can be followed by standard aids and advice to improve reading. Only in case of insufficient effect additional testing should take place.

Impact of Visual Impairment on Vision-Related Quality of Life in Parkinson's Disease

BACKGROUND

Visual impairment is frequent and highly disabling in Parkinson's disease (PD); however, few studies have comprehensively evaluated its impact on vision-related quality of life.

OBJECTIVE

To evaluate the relationship between visual function tests and the visual impairment perceived by PD patients in daily living activities.

METHODS

We cross-sectionally evaluated 62 PD patients and 33 healthy controls (HC). Visual disability was measured with a comprehensive battery of primary visual function and visual cognition tests (visual outcomes), and vision-related quality of life was evaluated with the National Eye Institute 25-Item Visual Function Questionnaire (NEI VFQ-25). The relationship between visual outcomes and NEI VFQ-25 sub-scores was analyzed with Pearson's correlations and stepwise linear regression.

RESULTS

In PD patients, and not in HC, most NEI VFQ-25 sub-scores were significantly correlated with Cube Analysis and Dot Counting from Visual Object and Space Perception (VOSP) battery (visual perception), Clock Drawing Test (visuoconstructive capacity) and Trail Making Test part-A (visual attention and processing speed) and to a lesser extent with high- and low-contrast visual acuity. Dot Counting (VOSP) was the test primarily associated with most NEI VFQ-25 sub-scores (5 out of 12). Roth-28 color test was the one that best explained the variance of Peripheral Vision (R2: 0.21) and Role Difficulties (R2: 0.36) sub-scores of NEI VFQ-25, while photopic contrast sensitivity explained 41% of Driving sub-score variance.

CONCLUSION

Vision-related quality of life in PD is mainly influenced by alterations in visual perception, visuoconstructive capacity and visual attention and processing speed. Future studies are warranted to confirm and further extend our findings.