SUMMARY
Background:
Definite diagnosis of Alzheimer's disease (AD) is only possible through neuropathological examination, and criteria for clinical diagnosis are essentially based on exclusion of other dementing conditions. ln 1994, Scinto et ai. observed pupil hypersensitivity to tropicamide in patients with AD, which is compatible with the reduced leveis of acetylcholine in the disease. However, later studies did not confirm these results.
Purpose:
To investigate the hypothesis of pupil hypersensitivity to tropicamide for the diagnosis of AD, using a simple methodology.
Material and Methods:
Ten patients (20 eyes) with clinical diagnosis of AD and ten age-matched contrals completed the study. Pupil measurements were dane with patients and contrals seated in a place with standardized illumination, looking at a focal point six meters away. We have used a millimeter ruler to measure the horizontal pupil diameter before and after 15 and 30 minutes of instillation of one drop of 0.02% tropicamide in each eye.
Results:
There were no significant differences between pupil dilation in patients and contrals for any of the measuring times nor for the percentage of total pupil diameter variation. We have observed a tendency to higher values of pupil dilation in the group of patients with AD when compared to contrals, although without reaching statistical significance.
Conclusion:
In the present study, the use of a simplified methodology for measuring pupil diameter following instillation of 0.02%o tropicamide did not allow differentiation between patients with AD and contrals.
Keywords:
Alzheimer's disease; Pupil; Tropicamide