Mydriatic effect of phenylephrine 10% (aq) vs phenylephrine 2.5% (aq).

Pupil dilation from commercially available phenylephrine compounds was studied in a group of 11 subjects. Phenylephrine 10% (aq) did not produce significantly more mydriasis than phenylephrine 2.5% (aq) in the general population (P less than 0.05). This suggests that phenylephrine 2.5% can be used instead of phenylephrine 10% for diagnostic dilation.