title: Evaluating the potentiating effect of amethocaine on tropicamide-induced mydriasis in darkly pigmented irides, using infrared pupillometry.
abstract: OBJECTIVE
  To determine whether prior instillation of amethocaine would increase the rate and magnitude of tropicamide-induced pupillary dilatation in darkly pigmented irides.
  
  
  METHODS
  A total of 50 healthy Africans aged 18-40 years, with darkly pigmented irides, received a drop of amethocaine in one eye and a drop of placebo in the contralateral eye, followed by two drops of tropicamide in both eyes. Serial pupil diameters were measured using a monocular infrared video pupillometer. Rate of pupillary dilatation was compared in both eyes. Survival statistics were calculated for the time taken to reach a clinically effective dilatation, clinically effective diameter (CED) of 6.0 mm.
  
  
  RESULTS
  Mean difference in pupil diameters between amethocaine- and placebo-treated eyes was 0.30 ± 0.09 mm (P < 0.002). In all, 62% of amethocaine-treated eyes and only 46% of placebo-treated eyes reached the CED.
  
  
  CONCLUSIONS
  We observed a small but statistically significant potentiating effect of a drop of amethocaine on tropicamide-induced dilatation within 20 minutes.
authors.affiliation: Department of Ophthalmology, College of Medicine, University of Ibadan/University College Hospital, Ibadan, Nigeria.
authors.forename: Olufunmilola A
authors.initials: OA
authors.lastname: Ogun
authors.affiliation: Consulting Biomedical Engineer, Cedar Park, TX, USA. ; Senior Biomedical Engineer, Optical Radiation Branch, Bioeffects Division, Air Force Research Laboratory, Tri-Services Research Laboratory, Fort Sam Houston, Texas, USA.
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Oliver
authors.affiliation: Department of Ophthalmology, College of Medicine, University of Ibadan/University College Hospital, Ibadan, Nigeria.
authors.forename: Adeyinka O
authors.initials: AO
authors.lastname: Ashaye
authors.affiliation: Department of Ophthalmology, College of Medicine, University of Ibadan/University College Hospital, Ibadan, Nigeria.
authors.forename: Benedictus Gk
authors.initials: BG
authors.lastname: Ajayi
keywords: amethocaine; dilatation; potentiating effect; pupil; tetracaine; tropicamide