Randomized double-blind study of phenylephrine 2.5% vs 10% on pupillary dilation

Area of Science:

• Ophthalmology
• Pharmacology

Background:

• Pupillary dilation is essential for comprehensive eye examinations.
• Phenylephrine is a common mydriatic agent used in ophthalmology.
• Comparing different concentrations of phenylephrine can optimize clinical practice.

Purpose of the Study:

• To evaluate and compare the efficacy of phenylephrine 2.5% versus 10% in achieving pupillary dilation.
• To assess and compare the side-effects associated with each phenylephrine concentration.

Main Methods:

• A randomized controlled trial involving 564 patients at Eye Clinic Srinagarind Hospital.
• Patients received either 1% tropicamide with 10% phenylephrine (Group 1) or 1% tropicamide with 2.5% phenylephrine (Group 2).
• Pupil diameter, blood pressure, and heart rate were measured pre- and post-instillation.

Main Results:

• The 10% phenylephrine group achieved significantly greater mean pupillary dilation compared to the 2.5% phenylephrine group (P < 0.05).
• No significant differences in systolic or diastolic blood pressure were observed between the groups post-instillation.
• A statistically significant increase in heart rate was noted in the 10% phenylephrine group compared to the 2.5% group.

Conclusions:

• Phenylephrine 10% in combination with tropicamide 1% offers superior pupillary dilation efficacy compared to phenylephrine 2.5% with tropicamide 1%.
• While both concentrations are safe regarding blood pressure changes, the higher concentration is associated with a greater heart rate increase.