title: Comparison of objective refraction in darkness to cycloplegic refraction: a pilot study.
abstract: BACKGROUND
  The aim was to assess non-cycloplegic objective refraction in darkness using an open-field auto-refractor, and furthermore to compare it with distance cycloplegic subjective refraction and distance cycloplegic retinoscopy in the light, in children and young adults.
  
  
  METHODS
  Twenty-three, visually-normal, young-adults (46 eyes) ages 23 to 31 years, and five children (10 eyes) ages five to 12 years, participated in the study. The spherical component of their refraction ranged from -2.25 D to +3.75 D with a mean of +1.80 D, and a mean cylinder of -0.70 D. Three techniques were used to assess refractive error. An objective measure of the non-cycloplegic refractive state was obtained using an open-field autorefractor (WAM-5500) after five minutes in the dark to allow for dissipation of accommodative transients and relaxation of accommodation. In addition, both distance retinoscopy and subjective distance refraction were performed following cycloplegia (Cyclopentolate, 1%) using conventional clinical procedures. All measurements were obtained on the same day within a single session. The spherical component of the refraction was compared among the three techniques in both the children and adults.
  
  
  RESULTS
  There was no significant difference in spherical refraction among the three techniques: non-cycloplegic objective refraction in the dark, distance cycloplegic retinoscopy and distance cycloplegic subjective refraction, in either the adults [F(2, 137) = 0.79, p = 0.45] or the children [F(2, 27) = 0.47, p = 0.62]. Mean difference in the spherical component between refraction in the dark and the cycloplegic distance retinoscopy was -0.34 D (r = 0.89) in the adults and +0.14 D (r = 0.96) in the children. The mean difference in spherical component between refraction in the dark and the cycloplegic distance subjective refraction was -0.25 D (r = 0.92) in the adults and -0.05 D (r = 0.95) in the children.
  
  
  CONCLUSIONS
  Comparison of the spherical refractive component between the three techniques was not significantly different and furthermore, they were highly correlated in both the children and adults in this pilot study. Non-cycloplegic refraction in the dark may provide a reliable adjunct or alternative to conventional cycloplegic refraction in both children and young adults.
authors.affiliation: Midwestern University, Glendale, Arizona, USA. drmurali@gmail.com.
authors.forename: Balamurali
authors.initials: B
authors.lastname: Vasudevan
authors.affiliation: Optometry - Vision Science, SUNY, New York, New York, USA.
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Ciuffreda
authors.affiliation: Midwestern University, Glendale, Arizona, USA.
authors.forename: Kelly
authors.initials: K
authors.lastname: Meehan
authors.affiliation: Midwestern University, Glendale, Arizona, USA.
authors.forename: Dejana
authors.initials: D
authors.lastname: Grk
authors.affiliation: Midwestern University, Glendale, Arizona, USA.
authors.forename: Misty
authors.initials: M
authors.lastname: Cox
mesh_terms: D000328:Adult; D002648:Child; D002675:Child, Preschool; D003519:Cyclopentolate / Q000008:administration & dosage*; D003623:Dark Adaptation / Q000502:physiology*; D006801:Humans; D009184:Mydriatics / Q000008:administration & dosage*; D010865:Pilot Projects; D011680:Pupil / Q000187:drug effects; D012029:Refraction, Ocular / Q000502:physiology*; D042262:Retinoscopy / Q000379:methods*; D055815:Young Adult
chemical_list: D009184:Mydriatics; D003519:Cyclopentolate
keywords: accommodation; children's vision; cycloplegia; refraction