title: Spherical equivalent refractive error in preschool children from a population with a high prevalence of astigmatism.
abstract: OBJECTIVE
  To describe spherical equivalent (sph eq) refractive errors in preschool members of a Native American tribe with a high prevalence of astigmatism.
  
  
  METHODS
  Cycloplegic autorefraction measurements were obtained for 819 three- and four-year-old Tohono O'odham children, with follow-up measurements in 146 after 4 to 8 years.
  
  
  RESULTS
  Mean sph eq was significantly more hyperopic in the astigmatic group than in the non-astigmatic group (1.24 vs. 0.87 D). At follow-up, prevalence of hyperopic sph eq and hyperopic astigmatism had significantly decreased, and prevalence of emmetropic/myopic sph eq and myopic astigmatism had significantly increased. The decrease in mean sph eq was similar in astigmats and non-astigmats. Astigmatism did not change over time.
  
  
  CONCLUSIONS
  Most preschool children in this highly astigmatic population are hyperopic, with astigmats showing higher mean hyperopic sph eq than non-astigmats. Astigmats and non-astigmats show a similar decrease in amount of hyperopic sph eq over follow-up of 4 to 8 years.
authors.affiliation: Department of Ophthalmology and Vision Science, The University of Arizona, Tucson, Arizona, USA. vdobson@eyes.arizona.edu
authors.forename: Velma
authors.initials: V
authors.lastname: Dobson
authors.forename: Erin M
authors.initials: EM
authors.lastname: Harvey
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Miller
mesh_terms: D001130:Arizona / Q000453:epidemiology; D001251:Astigmatism / Q000150:complications / Q000453:epidemiology* / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005500:Follow-Up Studies; D006801:Humans; D011159:Population Surveillance; D015995:Prevalence; D011379:Prognosis; D012029:Refraction, Ocular / Q000502:physiology*; D012030:Refractive Errors / Q000150:complications / Q000453:epidemiology* / Q000503:physiopathology; D012189:Retrospective Studies; D013997:Time Factors