Pupil dilation test in the diagnosis of Alzheimer's disease / 中华老年医学杂志

ABSTRACT

Objective To determine whether pupil response to dilute tropicamide could be used as a diagnostic test for Alzheimer's disease (AD). Methods Pupil diameters of both eyes were measured simultaneously by an infra red automatic pupil diameter recorder and analyzer every 0 1 second for 30 minutes after instillation of 0 01% tropicamide to one eye and normal saline to the other. Three groups of patients were studied 52 patients with AD, 33 with vascular dementia (VD), and 58 elderly controls. The percent change in pupil diameter of the treated eye was examined automatically by the analyzer. After finding the cut off point for differential diagnosis by receiver operator characteristic curve (ROC), its sensitivity, specificity and Kappa coefficient were calculated. Results Mean percent change in diameters of the treated eye showed a trend of fastest maximum dilation in AD group, and was significantly different from other groups at all the measurement time points after 10th minute instillation. The difference was most significant at the 18th minute after instillation, and 15% was used as a cut off point, the sensitivity was 0 81,specificity 0 79 0 82, and Kappa coefficient 0 62 0 67. Conclusions Pupil dilation test could be used as a screening method in the diagnosis of Alzheimer's disease, or as a tool for differential diagnosis between AD and VD.