title: Spherical subjective refraction with a novel 3D virtual reality based system.
abstract: OBJECTIVE
  To conduct a clinical validation of a virtual reality-based experimental system that is able to assess the spherical subjective refraction simplifying the methodology of ocular refraction.
  
  
  METHODS
  For the agreement assessment, spherical refraction measurements were obtained from 104 eyes of 52 subjects using three different methods: subjectively with the experimental prototype (Subj.E) and the classical subjective refraction (Subj.C); and objectively with the WAM-5500 autorefractor (WAM). To evaluate precision (intra- and inter-observer variability) of each refractive tool independently, 26 eyes were measured in four occasions.
  
  
  RESULTS
  With regard to agreement, the mean difference (±SD) for the spherical equivalent (M) between the new experimental subjective method (Subj.E) and the classical subjective refraction (Subj.C) was -0.034D (±0.454D). The corresponding 95% Limits of Agreement (LoA) were (-0.856D, 0.924D). In relation to precision, intra-observer mean difference for the M component was 0.034±0.195D for the Subj.C, 0.015±0.177D for the WAM and 0.072±0.197D for the Subj.E. Inter-observer variability showed worse precision values, although still clinically valid (below 0.25D) in all instruments.
  
  
  CONCLUSIONS
  The spherical equivalent obtained with the new experimental system was precise and in good agreement with the classical subjective routine. The algorithm implemented in this new system and its optical configuration has been shown to be a first valid step for spherical error correction in a semiautomated way.
authors: Davalor Research Center (DRC), Universitat Politècnica de Catalunya, Terrassa, Spain.
authors: Jaume
authors: J
authors: Pujol
authors: Davalor Research Center (DRC), Universitat Politècnica de Catalunya, Terrassa, Spain.
authors: Juan Carlos
authors: JC
authors: Ondategui-Parra
authors: Department of Applied Statistics, Universitat Autònoma de Barcelona, Spain.
authors: Llorenç
authors: L
authors: Badiella
authors: Davalor Research Center (DRC), Universitat Politècnica de Catalunya, Terrassa, Spain. Electronic address: carles.otero.molins@cd6.upc.edu.
authors: Carles
authors: C
authors: Otero
authors: Davalor Research Center (DRC), Universitat Politècnica de Catalunya, Terrassa, Spain.
authors: Meritxell
authors: M
authors: Vilaseca
authors: Davalor Research Center (DRC), Universitat Politècnica de Catalunya, Terrassa, Spain.
authors: Mikel
authors: M
authors: Aldaba
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D009907:Optometry / Q000379:methods*; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000175:diagnosis*; D012031:Refractometry / Q000295:instrumentation / Q000592:standards; D015203:Reproducibility of Results; D055815:Young Adult
keywords: Agreement; Autorefractor; Concordancia; Precision; Precisión; Realidad virtual; Refracción subjetiva; Subjective refraction; Virtual reality