title: Randomized double-blind study of phenylephrine 2.5% vs 10% on pupillary dilation.
abstract: OBJECTIVE
  To compare the efficacy of phenylephrine 2.5% versus 10% on pupillary dilation, and also compare their side-effects.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand. yosanan@kku.ac.th
authors.forename: Yosanan
authors.initials: Y
authors.lastname: Yospaiboon
authors.forename: Patanaree
authors.initials: P
authors.lastname: Luanratanakorn
authors.forename: Chedsada
authors.initials: C
authors.lastname: Noppawinyoowong
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D004311:Double-Blind Method; D005127:Eye Color; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009184:Mydriatics / Q000008:administration & dosage*; D010656:Phenylephrine / Q000008:administration & dosage*; D011680:Pupil / Q000187:drug effects*
chemical_list: D009184:Mydriatics; D010656:Phenylephrine