Low contrast stimuli enhance PERG sensitivity to the visual dysfunction in Parkinson's disease

The Relation Between Visual Hallucinations and Visual Evoked Potential in Parkinson Disease

“…32,33 De novo idiopathic Parkinson patients exhibit pattern ERGs and VEPs with significantly longer latencies, and this difference is reduced by levodopa. 34,35 Earlier, it was widely accepted that visual hallucinations were caused by stimulation of the visual pathway. However, the hallucinations described by Cogan 36 as ''release hallucinations'' are caused by disruption of the normal flow of visual impulses to the occipital cortex, with the consequent release of the endogenous cerebral activity of the visual system.…”

The possible role of retinal dopaminergic system in visual performance

“…Patients with PD treated with L-dopa exhibited reduced b-wave amplitude and normal b-wave latency in response to a high-contrast checkerboard stimulus (Nightingale et al, 1986;Gottlob et al, 1987). With decreasing contrast, PERG latency increased at a faster rate in untreated patients with PD than treated patients or control patients (Peppe et al, 1992). Delayed PERG latencies in untreated patients with PD were restored with dopaminergic therapy.…”

Oculo‐visual abnormalities in Parkinson's disease: Possible value as biomarkers

“…96,97 Reduced amplitudes of the ERG a-and bwaves, 98-101 the scotopic oscillatory potentials OP2 and OP3, and the overall index (OP1 + OP2 + OP3) were seen in PD patients, with prolonged mean peak times in OP1, OP2, OP3, and OP4. 21,99 In addition, the amplitude and latency of the pattern ERG P50 compound were reduced and delayed; 33,61,87,98,[102][103][104][105] and increased VEP latency (P100 and N70) has been reported in subsets of PD patients. 56,71,100,103,[106][107][108][109] Several lines of evidence support that ERG and VEP abnormalities are closely related to impaired dopaminergic transmission.…”