Abstract
Purpose:
To assess contrast sensitivity (CS) and visual hallucinations (VH) in individuals with Parkinson’s disease. Patients with Parkinson’s disease who experience hallucinations may show impaired CS, a relationship previously reported in people with low vision who experience Charles Bonnet Syndrome.
Methods:
A total of 964 members of the online patient community ‘PatientsLikeMe’ were invited via email to participate in this study. 269 members completed the study; 153 of this group were patients with Parkinson's disease, 116 were controls (other disorders). Participants completed, online, a modified version of the University of Miami Parkinson’s Disease Hallucinations Questionnaire (UM-PDHQ) and a test of CS similar to the Pelli Robson chart.
Results:
Results from the UM-PDHQ showed that 18% of people in the Parkinson’s group currently experienced VH versus 9% in the control group. Hallucinations reported by participants with Parkinson’s disease included mice, cats, people, distorted faces, furniture or complex patterns. Both groups, participants with Parkinson’s disease (M: 1.85, SD: .36) and the control group (M: 1.75, SD: .35) showed relatively good CS as measured with the online letter test (F(1, 269)= 1.49, p=.22). Individuals with current VH showed relatively low CS scores (M: 1.69, SD: .36) compared to individuals who had never had VH (M:1.81, SD: .35), or had previously (M: 1.80, SD: .37) experienced VH. This difference, however, did not reach statistical significance (F(2, 263)= 1.55, p= .22). CS differences in the Parkinson’s disease group between those with VH (M: 1.69, SD: .34) and those with no current VH (never VH - M: 1.77, SD: .34, VH but not in past month - M: 1.74, SD: .40) were small.
Conclusions:
More patients with Parkinson’s disease reported visual hallucinations than the control group, however, both groups showed relatively good CS. Interestingly, participants who reported VH, irrespective of disease status, showed relatively low CS compared to participants who did not. This difference is of clinical interest. Contacting subjects via an online health social network is a novel method of conducting vision research that allows large numbers of individuals to be contacted quickly, including those in remote communities.
Keywords: 478 contrast sensitivity •
584 low vision •
759 visual impairment: neuro-ophthalmological disease