title: The effect of daily use of brimonidine tartrate on the dark-adapted pupil diameter.
abstract: OBJECTIVE
  To investigate the effect of daily brimonidine tartrate 0.15% on the dark-adapted pupil diameter.
  
  
  METHODS
  Observational case series.
  
  
  METHODS
  Ten normal volunteers administered brimonidine to their right eyes once daily. Four to six hours later, infrared pupil photographs were taken after dark adaptation. Measurements were performed at baseline; on treatment days 1, 5, 11, and 18; and on washout days 1 and 2.
  
  
  RESULTS
  One subject had no response. The nine responding subjects showed an average maximum antimydriatic effect of -1.63 mm (range, -0.57 mm--2.30 mm); all subjects experienced tachyphylaxis. Five subjects showed rebound mydriasis (mean maximum rebound +0.87 mm larger than baseline; range 0.50 mm-1.22 mm). The untreated pupil also responded, showing antimydriasis (two subjects), rebound mydriasis (two subjects), or paradoxical direct mydriasis (one subject).
  
  
  CONCLUSIONS
  Once-daily use of brimonidine tartrate to prevent dark-induced pupil dilation can lead to tachyphylaxis and rebound mydriasis.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Texas Tech University Health Sciences Center, 3601 Fourth Street, Lubbock, TX 79430-7217, USA. Sandra.brown@ttuhsc.edu
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Brown
authors.forename: Arshad M
authors.initials: AM
authors.lastname: Khanani
authors.forename: David L
authors.initials: DL
authors.lastname: McCartney
mesh_terms: D000293:Adolescent; D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage*; D000328:Adult; D000068438:Brimonidine Tartrate; D003623:Dark Adaptation / Q000187:drug effects*; D006801:Humans; D015878:Mydriasis / Q000209:etiology; D009883:Ophthalmic Solutions / Q000008:administration & dosage; D011680:Pupil / Q000187:drug effects*; D011810:Quinoxalines / Q000008:administration & dosage*; D012008:Recurrence; D013618:Tachyphylaxis
chemical_list: D000316:Adrenergic alpha-Agonists; D009883:Ophthalmic Solutions; D011810:Quinoxalines; D000068438:Brimonidine Tartrate