Cocaine and hydroxyamphetamine testing in Horner’s syndrome Cocaine and hydroxyamphetamine testing in Horner’s syndrome. A: Right ptosis and miosis. B: After administration of cocaine eye drops, the left pupil dilates but the right pupil does not dilate, confirming Horner’s syndrome on the right. C: After administration of hydroxyamphetamine eye drops, the right pupil dilates, confirming functioning third-order neurons, localizing the problem to the first-order or second-order neurons. D: Right ptosis and miosis. E: After administration of cocaine eye drops, the left pupil dilates but the right pupil does not dilate, confirming Horner’s syndrome. F: After administration of hydroxyamphetamine eye drops, the right pupil does not dilate, localizing the problem to the third-order neurons. Reproduced with permission from Martin T, Corbett J: Practical Neuroophthalmology. New York: McGraw-Hill Education; 2013. Cranial Nerves 2 and 3, Clinical Neurology and Neuroanatomy: A Localization-Based Approach Citation: Berkowitz AL. Clinical Neurology and Neuroanatomy: A Localization-Based Approach; 2016 Available at: http://neurology.mhmedical.com/DownloadImage.aspx?image=/data/books/1984/berkneuro_ch10_f005d-f.png&sec=148034808&BookID=1984&ChapterSecID=147771056&imagename= Accessed: November 13, 2017 Copyright © 2017 McGraw-Hill Education. All rights reserved