title: Effective pupil dilatation with a mixture of 0.75% tropicamide and 2.5% phenylephrine: A randomized controlled trial.
abstract: OBJECTIVE
  To compare the efficacy in pupil dilatation between a mixture containing 0.75% tropicamide and 2.5% phenylephrine and the alternate application of 1% tropicamide and 10% phenylephrine eye drops.
  
  
  METHODS
  Patients requiring pupil dilatation were randomized to receive one drop of the mixture every 10 min for four times or our standard application of one drop of 1% tropicamide alternating with one drop of 10% phenylephrine every 10 min for two cycles. Pupil size was measured under bright light with the pupil gauge before, and every 5 min after initial application for 40 min. Application of the drops was discontinued once the pupil diameter reached 7 mm. Blood pressure and pulse rate were monitored every 15 min.
  
  
  RESULTS
  Of 40 patients (age 57.3+/-10.9 years, range 35-70 years), 22 were randomized into the mixture group and 18 into the alternate drug group. Baseline pupil sizes were 1.7+/-0.5 mm in the mixture group and 1.8+/-0.4 mm in the alternate drug group. The pupils were successfully dilated to 7 mm within 40 min in 17 patients of the mixture group compared to seven patients in the alternate drug group ( P =0.004, Log Rank test). The mean pupil sizes at 40 min were 6.6+/-0.8 and 6.0+/-0.9 mm in the mixture and alternate drug groups respectively ( P =0.050, t-test). Blood pressure and pulse rate were stable and similar in both groups.
  
  
  CONCLUSIONS
  The mixture of 0.75% tropicamide and 2.5% phenylephrine is superior to our standard application of 1% tropicamide alternating with 10% phenylephrine. It provides faster and more successful pupil dilatation within 40 min.
authors.affiliation: Department of Ophthalmology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkoknoi, Bangkok, Thailand. siatr@mahidol.ac.th
authors.forename: Adisak
authors.initials: A
authors.lastname: Trinavarat
authors.forename: Auengporn
authors.initials: A
authors.lastname: Pituksung
mesh_terms: D000328:Adult; D000368:Aged; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004338:Drug Combinations; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009184:Mydriatics / Q000008:administration & dosage*; D009883:Ophthalmic Solutions; D009887:Ophthalmoscopy / Q000379:methods*; D010656:Phenylephrine / Q000008:administration & dosage*; D011680:Pupil / Q000187:drug effects*; D015203:Reproducibility of Results; D014331:Tropicamide / Q000008:administration & dosage*
chemical_list: D004338:Drug Combinations; D009184:Mydriatics; D009883:Ophthalmic Solutions; D010656:Phenylephrine; D014331:Tropicamide
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