Bell's phenomenon in normal adults and in Parkinson's disease.

Bell's phenomenon (upward and outward rolling of the eyeballs on forcible closure of the eyelids) was studied in normal adults and in patients suffering from Parkinson's disease. Advancing age correlates with diminution of the response but this was more severe in Parkinson's disease and was thus shown to be suppressive of the normal mechanism. Asymmetrical responses, the right eye being nearly always more affected, were frequently encountered in both groups though more numerous in Parkinsonism. There was a tendency toward a lesser incidence of Bell's phenomenon in the more advanced stages of the disease but without a clearcut correlation.