Clinical equivalence between a combination of 1% tropicamide/2.5% phenylephrine hydrochloride and 1% tropicamide/10% phenylephrine in pupillary dilatation efficacy in dark irides: a double blind randomized controlled trial

Abstract

Objectives : To compare the efficacy of pupillary dilatation between 1%tropicamide with 2.5%phenylephrine hydrochloride and 1%tropicamide with 10%phenylephrine hydrochloride in dark irides. Design : A double blind randomized controlled trial. Setting : Chulalongkorn Hospital, Bangkok. Participants : One hundred and ninty six out-patient department patients who required pupillary dilatation. Methodology : The pateints were randomized into two groups. The experimental group received 2.5% phenylephrine hydrochloride with 1% tropicamide and the conventional group received 10% phenylephrine hydrochloride with 1% tropicamide. The combination of drops were instilled every 10 minutes for three times. The horizontal diameter of the pupil was measured at 30 minutes. Results : The mean pupil size at 30 minutes in the experimental group (2.5% Phenylephrine) was 7.35 mm (SD = 0.9) and the 95% CI was 7.17-7.53 mm. The mean pupil size of the conventional group (10% Phenylephrine) was 7.58 mm (SD = 0.77). The mean difference in pupil size between these groups was 0.22 mm and the 95% CI was 0.46mm to 0.007 mm. There was no difference found in terms of adverse effects. Conclusion : When combined with 1% tropicamide, 2.5% phenylephrine hydrochloride was clinically equivalent to 10% phenylephrine hydrochloride in terms of pupillary dilatation in dark irides.