Effects of Two Commonly Used Mydriatics on Choroidal Thickness: Direct and Crossover Effects

Abstract

To investigate the effect of 2 commonly used mydriatics on choroidal thickness using enhanced depth imaging optical coherence tomography (EDI-OCT). In this prospective study, 90 healthy subjects were enrolled. The participants were randomly divided into 3 groups based on the application of drops. One eye of each subject received a drop of tropicamide 1% in the tropicamide group (n=30), a drop of phenylephrine 2.5% in the phenylephrine group (n=30), and a drop of artificial tear in the control group (n=30). Drops were given thrice at 5 min intervals. Subfoveal choroidal thickness (SFCT) was measured using EDI-OCT before and at 45 min after drop application in both the dilated eye and nondilated contralateral eye. The SFCT was significantly decreased after drop instillation in both the dilated eye and contralateral eye in the tropicamide group (P<0.001 and P=0.001, respectively) and in the phenylephrine group (P<0.001 and P=0.001, respectively). However, the SFCT did not significantly differ after drop instillation in either the dropped eye or contralateral eye in the control group (P=0.108 and P=0.695, respectively). The findings of the present study revealed that tropicamide and phenylephrine cause a decrease in choroidal thickness.