We evaluated pupil light reflex (PLR) in patients with Parkinson's disease (PD) and normal controls by means of pupillometry and explored its possible relation to clinical characteristics in parkinsonian patients. PLR was evaluated using pupillometry in 66 patients with PD without clinical evidence of autonomic dysfunction and 44 healthy matched controls. PLR was elicited by single flash stimuli of 24.6 candelas/m(2) intensity and 20 ms duration, and six parameters were studied after full recording of pupil's movement. A significant increase in latency (T1) and significant decrease in amplitude (R1-R2), maximum constriction velocity (V(max)), as well as maximum acceleration (AC(max)) was found in parkinsonian patients. There was no significant difference in initial radius (R1) and minimum radius (R2) values. Of the parameters studied, AC(max) emerged as a significant predictor for discrimination between PD patients and controls. There was no significant correlation between pupillometry parameters and clinical characteristic of patients (disease duration, stage, and the Unified Parkinson's Disease Rating motor scale). The study demonstrates PLR disorder in PD patients even without overt clinical autonomic dysfunction. Pupillometry appears to be a useful and noninvasive method for exploration of PLR alterations in PD and may prove to be useful for the early detection of subclinical autonomic nervous system dysfunction.

The purpose of this study was the evaluation of pupil light reflex (PLR) in patients with Parkinson's disease (PD) by using a modern pupillometry system and the investigation of its potential relationship with dopamine transporter imaging (DaTSCAN), which is an objective method for the evaluation of presynaptic dopaminergic system. PLR was evaluated using pupillometry in 35 patients with PD without clinical evidence of autonomic dysfunction and 44 healthy matched controls. PLR was elicited using a fully automated pupillometry system and six parameters were measured. Dopamine transporter imaging was performed using radioactive ioflupane (123)I-FP-CIT [(123)I-N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)-nortropane]. A significant increase in latency and a significant decrease in amplitude, maximum constriction velocity, as well as maximum acceleration were observed in PD patients. There was no significant difference in initial radius and minimum radius values. Investigating the relationship between pupillometry parameters and (123)I-FP-CIT binding values, we correlated values from the semiquantitative analysis of radioligand uptake with pupillometry parameters, but we found no significant correlation. This study demonstrates PLR impairment in patients with PD without overt autonomic dysfunction. This impairment does not seem to correspond to the reduction of radioligand binding in the striatum as the result of presynaptic dopaminergic dysfunction, suggesting a different deterioration rate of these systems.

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