Mydriatic and Cardiovascular Effects of Phenylephrine 2.5% Versus Phenylephrine 10%, Both Associated with Tropicamide 1%

Background/aims: To evaluate and compare cardiovascular effects (blood pressure and heart rate) of phenylephrine 2.5% versus phenylephrine 10%, and compare pupil diameter before and after instillation of eyedrops.

Methods: A total of 58 patients scheduled for funduscopy were dilated with either phenylephrine 2.5% and tropicamide 1% (group 0, n = 29 patients, 58 eyes) or phenylephrine 10% and tropicamide 1% (group 1, n = 29 patients, 58 eyes). Only one drop per eye of each drug was administered. In both groups, pupil diameter, blood pressure and heart rate were measured before and 40 min after eyedrop instillation.

Results: We did not observe significant changes in blood pressure or heart rate. Mean pupil diameter in group 0, before the instillation of eyedrops, was 3.51 mm and, in group 1, 2.66 mm. After medication, mean values were 7.38 mm in group 0 and 7.42 mm in group 1. Mean variation was 3.87 mm in group 0 and 4.76 mm in group 1 (p < 0.001).

Conclusion: Our results corroborate the finding that one single drop of either 2.5 or 10% phenylephrine is safe and, when 1% tropicamide is combined, satisfactory pupil dilation is achieved.