A rapid and specific diagnostic test for Alzheimer's disease (AD), the
prevalent cause of dementia in the elderly, is currently unavailable.
The aim of this study was to verify the validity of the recently prop
osed 'Eye Test' in the identification of AD patients, based on their s
upposed greater mydriatic response to cholinergic antagonists. We rest
ed the pupillary response to the instillation of 0.01% tropicamide in
48 subjects: 15 patients with probable or possible Alzheimer's disease
, five patients with vascular dementia (VD), 16 elderly controls (EC)
and 12 young controls (YC). Mean pupil dilation in the treated eye at
30 and 40 min after drops instillation was not significantly different
among the four groups. The mean change in anisocoria at 30 min was si
gnificantly greater in the AD group (0.90 mm, S.D. 0.83) than in the Y
C group (0.21 mm, S.D. 0.46), but no significant difference was found
among the AD group, the EC group and the VD group. Our results, theref
ore, do not support the potential usefulness of the pupillary response
to dilute tropicamide for identifying individuals with AD. (C) 1998 E
lsevier Science Ireland Ltd. All rights reserved.