Several studies support the hypothesis that dopaminergic deficiency at the retinal level underlies some visual changes of achromatic vision in Parkinson's disease (PD). Impairment of the color-opponent pathway at the retinal level in PD has not been investigated. We previously reported that VEPs to blue-yellow (B-Y) chromatic stimuli display the highest vulnerability as compared to both red-green (R-G) and black-white stimuli in PD (Sartucci et al., Invest Ophthalmol and Visual Sci 1999, 40: S822). The aim of this study was to investigate in "de novo" PD patients at the relative involvement of chromatic and achromatic pathways at retinal level, by recording the PERG to both R-G and B-Y equiluminant stimuli and yellow-black (Y-Bk) luminance stimuli. We enrolled 12 PD patients (mean age 60.1 ± 8.3 years, range 46-74) not undergoing treatment with L-Dopa, as well as 11 age-matched controls. PERGs were recorded monocularly in response to R-G, B-Y and Y-Bk horizontal gratings of 0.3 c/deg and 90% contrast, reversed at (1 Hz) and displayed on a TV monitor at a viewing distance of 24 cm (59.2*59 deg field). In PD patients the mean PERG amplitude was dramatically reduced by about 45% for both chromatic- and luminance stimuli. Mean PERG latencies were significantly delayed. The amount of delay was stimulus-dependent (Y-Bk: 5.7 ms; R-G: 4.5 ms; B-Y: 14.3 ms). Present data indicate that both chromatic and achromatic PERGs are altered in PD before L-Dopa therapy. Overall, chromatic PERGs to B-Y equiluminant stimuli exhibit the largest changes, indicating that the reported vulnerability of VEPs to B-Y has a retinal component. The different extent of abnormalities for the different PERG modalities indicates differential retinal impairment of visual subsystems at least in the early stages of the disease.
|Original language||English (US)|
|Issue number||4 SUPPL.|
|State||Published - Dec 1 2000|
ASJC Scopus subject areas
- Clinical Neurology
- Psychiatry and Mental health