Anisocoria caused by Tropicamide instilled into the right eye only.
Tropicamide is occasionally administered in combination with p-hydroxyamphetamine (brand name Paremyd), which is a sympathomimetic. The use of the sympathomimetic drug causes the iris dilator muscle to be directly stimulated, causing increased dilation. In the United States, the sympathomimetic drop most commonly used along with tropicamide, is 2.5% phenylephrine hydrochloride (brand name AK-Dilate).
Tropicamide induces transient stinging and a slight and transient rise in intraocular pressure in the majority of patients. It may cause redness or conjunctivitis (inflammation) and also blurs near vision for a short while after instillation (care must be taken, and the patient must only drive when vision returns to normal). Tropicamide may, in very rare cases , cause an attack of acute angle-closure glaucoma. This tends to be in patients with narrow anterior chamberangles, and closure risk must be assessed by the practitioner prior to instillation.
Tropicamide is often preferred to atropine because atropine has a longer half-life, causing prolonged dilation and blurry vision for up to a week. Atropine has less sting effect, but can be toxic or fatal if ingested in large quantities by children or adults.
According to the researchers of the European Commission-funded ReDNet Project, in Russia tropicamide is currently abused (injected intravenously) as an inexpensive recreational deliriant drug. It is usually mixed with heroin, methadone, and other opioid drugs to potentiate the "rush" when injected intravenously.
^Bersani, F. S.; Corazza, O.; Simonato, P.; Mylokosta, A.; Levari, E.; Lovaste, R.; Schifano, F. (2013). "Drops of madness? Recreational misuse of tropicamide collyrium; early warning alerts from Russia and Italy". General Hospital Psychiatry35 (5): 571–3. doi:10.1016/j.genhosppsych.2013.04.013. PMID23706777.