title: Relative peripheral refraction in children: twelve-month changes in eyes with different ametropias.
abstract: OBJECTIVE
  To determine the peripheral refraction of children with different types of ametropias and to evaluate the relationship between central refractive changes, baseline relative peripheral refraction (RPR) and changes in RPR over a 12-month monitoring period.
  
  
  METHODS
  Cycloplegic central and peripheral refraction were performed biannually on the right eyes of children aged 6-9 for 12 months, using an open-view autorefractor. Peripheral refraction were measured along 10°, 20° and 30° from central fixation in both nasal and temporal fields. Refractive data were transposed into M, J0 and J45 vectors for analyses. RPR was determined by subtracting the central measurement from each peripheral measurement.
  
  
  RESULTS
  Hyperopic eyes showed relative peripheral myopia while myopic eyes had relative hyperopia across the central 60° horizontal field at baseline. Emmetropic eyes had relative myopia within but showed relative hyperopia beyond the central 30° field. However, there was no significant correlation between central refractive changes and baseline RPR or between changes in central refraction and RPR over twelve months in any refractive groups. Correlations between changes in PR and central myopic shift were found mainly in the nasal field in different groups. In the subgroup analysis on the initially emmetropic and the initially myopic groups, the subgroups with faster myopic progression did not have significantly different RPR from the subgroups with slower progression. The RPR pattern of the initially emmetropic and the initially myopic groups became more asymmetric at the end of the study period with a larger increase in relative hyperopia in the temporal field.
  
  
  CONCLUSIONS
  RPR patterns were different among hyperopic, emmetropic and myopic eyes. However, baseline RPR and changes in RPR cannot predict changes in central refraction over time. Our results did not provide evidence to support the hypothesis of RPR as a causative factor for myopic central refractive changes in children.
authors.affiliation: School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong. ttlee1@netvigator.com
authors.forename: Tsui-Tsui
authors.initials: TT
authors.lastname: Lee
authors.forename: Pauline
authors.initials: P
authors.lastname: Cho
mesh_terms: D044466:Asian People; D002648:Child; D002681:China; D058453:Emmetropia / Q000502:physiology*; D005260:Female; D006801:Humans; D006956:Hyperopia / Q000503:physiopathology*; D008297:Male; D009216:Myopia / Q000503:physiopathology*; D012029:Refraction, Ocular / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology*