Parkinson’s Disease Significantly Affects Contrast Sensitivity, Researchers Find

Different neurodegenerative disorders have been linked to worsening contrast sensitivity. This study highlights the importance of evaluating contrast sensitivity function under various lighting environments to fully understand the level of visual impairment in patients with Parkinson’s disease. Photo: Bisant A. Labib, OD. Click image to enlarge.Researchers from Spain explored how Parkinson’s disease impacts contrast sensitivity function (CSF) at six different conditions of illumination.The Index of Contrast Sensitivity (ICS) was used for this study. This indicated the overall CSF and compared different groups within a population. Two groups were evaluated: a Parkinson’s test group with 71 cases and a healthy control with 97 participants. These groups were exposed to six illumination conditions:Photopic without glare conditionsMesopic without glare conditionsPhotopic with G1 glare conditionsMesopic with G1 glare conditionsPhotopic with G2 glare conditionsMesopic with G2 glare conditionsG1 was described as “discomfort glare.” G2 was described as “disability glare.” LEDs were used to create the glare. Different light intensities were used to achieve each glare condition.After undergoing exposure and testing, researchers found significant differences between the two groups. The Parkinson’s test group showed significantly worse CSF compared to the control at all six illumination conditions. Impairment was most pronounced following the mesopic condition with G1 glare (ICS: 33 vs. 2.5). Although the visual performance of Parkinson’s participants declined as stages advanced, these findings correlated with increasing age as well.“To the best of our current knowledge, this is the first study to assess CSF systematically and report related ICS data under six controlled illumination conditions in participants with Parkinson’s disease, across different stages of disease progression and in comparison with age-matched healthy controls,” the authors mentioned in their paper. “These findings may contribute to a more comprehensive understanding of visual function across different stages of the disease.”Click here for the source. Herrero-Gracia A, Hernández-Andrés R, Perla-Muedra C, et al. Contrast sensitivity function in Parkinson’s disease: Effects of illumination and disease stage. Ophthalmic Physiol Opt. April 27, 2026. [Epub ahead of print]. This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.