ABSTRACT
PURPOSE: To compare the efficacy of phenylephrine 2.5% versus 10% on pupillary dilation, and also compare their side-effects. METHOD: Patients at the Eye Clinic Srinagarind Hospital were randomized into two groups. Patients in group 1 received 1% tropicamide and 10% phenylephrine, whereas those in group 2 received 1% tropicamide and 2.5% phenylephrine. Pupil diameter, blood pressure and heart rate were measured before and after eyedrop instillation. RESULTS: Five hundred and sixty four patients were randomized into 293 patients (group 1) and 271 patients (group 2), using simple random sampling method. Mean pupil diameters before instillation in group 1 were 4.43 +/- 1.13 mm in the right eye and 4.31 +/- 0.95 mm in the left eye, whereas those in group 2 were 4.45 +/- 1.0 mm in the right eye and 4.32 +/- 0.92 mm in the left eye. After the instillation, the mean pupil diameters in group 1 were 7.58 +/- 0.96 mm in the right eye and 7.60 +/- 1.03 mm in the left eye, whereas those in group 2 were 7.17 +/- 1.04 mm in the right eye and 7.07 +/- 1.06 mm in the left eye. The difference was statistically significant (P < 0.05). There was no significant difference in mean systolic and diastolic blood pressure after instillation between the two groups. However, the mean heart rate after instillation in group 1 was greater than the value in group 2 with statistically significant difference. CONCLUSION: Pupillary dilation with 1% tropicamide and 10% phenylephrine is more effective than 1% tropicamide and 2.5% phenylephrine with statistically significant difference. After single dose instillation, there was no significant difference in the mean blood pressure between the two groups.