The Pupil Diameter as a Possible Indicator of Neurodegenerative Diseases and Response to Acetylcholinesterase Inhibitors Therapy: In-Depth Measurements Following Topical Administration of Tropicamide and Pilocarpine

Background: The aim of this study is to assess whether pupillary modifications following ocular anticholinergic and cholinergic drugs can identify subjects with neurodegenerative diseases from early stages. Methods: 51 subjects were divided into 3 groups, according to different neurodegenerative diseases, and compared with a control group of 10 patients. Pupil diameter has been measured at different times after topical administration of tropicamide 0.01% in the right eye. Then, topical administration of pilocarpine 0.06% has been performed, followed by pupillary constriction measurement. Pupillary response rates were stratified according to acetylcholinesterase inhibitors intake. Results: Observed mydriasis and pupillary constriction was similar in all study groups at all evaluation times. Patients without acetylcholinesterase inhibitors intake presented greater mydriasis. Conclusions: Although it was not possible to observe significant differences among groups in terms of pupillary response, the analysis of pupillary features may become an useful tool to detect efficacy of acetylcholinesterase inhibitors.