title: Clinical evaluation of an eccentric infrared photorefractor: the PowerRefractor.
abstract: OBJECTIVE
  To evaluate the viability of the PowerRefractor as a screening tool for examining refractive errors in large samples of children.
  
  
  METHODS
  The variability of the PowerRefractor was estimated using four patients. The refractive error was determined using cyclopentolate and tropicamide as cycloplegic agents and compared to that determined in a non-cycloplegic situation. In a second study, the data provided by the PowerRefractor were compared to results obtained by autorefractor or retinoscopy for 150 children aged from 6 months to 5 years.
  
  
  RESULTS
  Variability study. Statistical analysis showed a statistically significant difference between cycloplegic and non-cycloplegic refraction for spherical and cylindrical refractive errors (p<0.0001 in all cases). There was no significant difference between the measurements made using tropicamide and cyclopentolate (p=0.33 and p=0.18, respectively). Comparison study. In 142 of 150 patients the difference between data obtained by the PowerRefractor and an autorefractor was within 1 D (spherical equivalent). However, there was a considerable difference between the data generated by the two methods in the remaining eight patients (up to 16 D).
  
  
  CONCLUSIONS
  The PowerRefractor proved to be a reliable tool for estimating refractive errors in young children. The apparatus is easy to handle and the simultaneous examination of both eyes makes the PowerRefractor ideal for obtaining data on refractive errors in large samples.
authors.affiliation: Department of Ophthalmology, Institute of Clinical Neuroscience, Göteborg University, Mölndal, Sweden.
authors.forename: Maths
authors.initials: M
authors.lastname: Abrahamsson
authors.forename: Josefin
authors.initials: J
authors.lastname: Ohlsson
authors.forename: Maria
authors.initials: M
authors.lastname: Björndahl
authors.forename: Hannah
authors.initials: H
authors.lastname: Abrahamsson
mesh_terms: D000293:Adolescent; D000328:Adult; D000550:Amblyopia / Q000175:diagnosis; D002675:Child, Preschool; D003519:Cyclopentolate / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007223:Infant; D007259:Infrared Rays; D008297:Male; D009184:Mydriatics / Q000008:administration & dosage; D009885:Ophthalmology / Q000295:instrumentation*; D011680:Pupil / Q000187:drug effects; D012030:Refractive Errors / Q000175:diagnosis*; D015203:Reproducibility of Results; D014331:Tropicamide / Q000008:administration & dosage; D015351:Vision Screening / Q000295:instrumentation* / Q000379:methods
chemical_list: D009184:Mydriatics; D003519:Cyclopentolate; D014331:Tropicamide