title: Use of the HARK autorefractor in children.
abstract: OBJECTIVE
  We investigated the reliability, accuracy, and repeatability of an autorefractor with the capability of over-refracting and measuring visual acuity for use in children in a prospective study.
  
  
  METHODS
  Before and after cycloplegia, 68 children (mean +/- SD age, 10 +/- 3 years, range 5-16 years) underwent autorefraction twice with the HARK 599 Autorefractor (Humphrey Instruments Inc., San Leandro, CA), subjective over-refraction through the HARK autorefractor, and subjective refraction using a phoro-optometer. After cycloplegia, retinoscopy was performed. Results are reported for one eye (left) of each child.
  
  
  RESULTS
  For 68 eyes of 68 children, before and after cycloplegia, correlation coefficients (R) for autorefraction reproducibility exceeded 0.95 for all comparisons of sphere and cylinder. R for spherical values for autorefraction vs. over-refraction was 0.93 and vs. subjective refraction 0.83 before cycloplegia and 0.94 and 0.97 after cycloplegia. Comparing values before and after cycloplegia, autorefraction, over-refraction, and subjective refraction, the data correlated > 0.81 for sphere and 0.75 to 0.87 for cylinder. Cycloplegic retinoscopy compared with autorefraction, over-refraction, and subjective refraction had R > 0.86 for sphere and cylinder for all comparisons except one. Cycloplegia increased the proportion of spherical equivalent values within 0.625 D of the subjective refraction from 41 of 68 eyes (61%) for auto- and over-refraction to 64 (94%) and 51 (75%) of the 68 eyes, respectively. A visual acuity of 20/30 or better was produced in 50 of 68 (73%) eyes with automated refraction before and after cycloplegia and in 62 (92%) with subjective refraction before cycloplegia and subjective refraction and retinoscopy after cycloplegia. Subjective over-refraction did not significantly improve the visual acuity.
  
  
  CONCLUSIONS
  In children, HARK autorefraction improved in accuracy, when compared to subjective refraction, and the level of visual acuity improved after cycloplegia. Over-refraction through the instrument did not improve the results before or after cycloplegia.
authors: Department of Ophthalmology, Jules Stein Eye Institute, Harbor/U.C.L.A. Medical Center, U.C.L.A. School of Medicine-Los Angeles and Torrance, California 90509, USA. isenberg@ucla.edu
authors: S J
authors: SJ
authors: Isenberg
authors: M
authors: M
authors: Del Signore
authors: G
authors: G
authors: Madani-Becker
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D009184:Mydriatics / Q000008:administration & dosage; D011446:Prospective Studies; D011680:Pupil / Q000187:drug effects; D012029:Refraction, Ocular; D015203:Reproducibility of Results; D014787:Vision Tests / Q000295:instrumentation*; D014792:Visual Acuity / Q000502:physiology*
chemical_list: D009184:Mydriatics