Lee, N.G., Lin, L.-W., Mehta, S. and Freitag, S.K. 2015. Response to phenylephrine testing in upper eyelids with ptosis. Digital Journal of Ophthalmology. 21, 3 (Sep. 2015), 35–39. DOI:https://doi.org/10.5693/djo.01.2015.05.001.