title: Colvard pupillometer measurement of scotopic pupil diameter in emmetropes and myopes.
abstract: OBJECTIVE
  To prospectively compare the scotopic pupil size between emmetropes and myopes using a Colvard pupillometer.
  
  
  METHODS
  The pupil diameters of 55 normal subjects and 55 healthy myopic subjects were measured with the Colvard pupillometer in a low-light situation that simulated the level of light encountered while driving at night.
  
  
  RESULTS
  The mean (+/- SD) age of the emmetropic subjects was 30.78 years +/- 10.03 (range, 18-54 years) and the mean (+/- SD) age of the myopic subjects was 27.35 years +/- 8.43 (range, 21-52 years). The mean (+/- SD) scotopic pupil diameter was 6.46 +/- 0.90 mm (range, 4.5-8.0 mm) in the emmetropic group and 6.98 +/- 0.67 mm (5.5-8.5 mm) in the myopic group. The unpaired Student t-test showed that the difference in the scotopic pupil diameter between emmetropes and myopes was statistically significant (P =.0001).
  
  
  CONCLUSIONS
  The mean scotopic pupil diameter in myopes was larger than that in emmetropes. Therefore, a large ablation zone of the cornea or an appropriate optical size of the phakic intraocular lens should be considered in refractive surgery. Preoperative scotopic pupil measurements may be necessary in all refractive patients.
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Winai
authors.initials: W
authors.lastname: Chaidaroon
authors.forename: Wimolwan
authors.initials: W
authors.lastname: Juwattanasomran
mesh_terms: D000293:Adolescent; D000328:Adult; D001837:Body Weights and Measures; D003623:Dark Adaptation; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D005260:Female; D006801:Humans; D007498:Iris / Q000033:anatomy & histology; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology*; D011446:Prospective Studies; D011680:Pupil / Q000502:physiology*