title: Prevalence of myopia between 3 months and 5 1/2 years in preterm infants with and without retinopathy of prematurity. Cryotherapy for Retinopathy of Prematurity Cooperative Group.
abstract: OBJECTIVE
  The purpose of the study was to examine spherical equivalent refractive errors, especially myopia, at six ages between 3 months and 5 1/2 years post-term in preterm children with birth weights of less than 1251 g.
  
  
  METHODS
  A cohort study.
  
  
  METHODS
  There were a total of 827 participants in the multicenter study of cryotherapy for retinopathy of prematurity (ROP). Approximately one third of the eyes did not develop ROP, whereas two thirds developed mild-to-severe ROP. None of the eyes underwent cryotherapy.
  
  
  METHODS
  Refractive error was measured at 3 months, 1 year, and 5 1/2 years term due date at the five long-term follow-up centers. In most eyes, refractive error also was measured at 2, 3 1/2, and 4 1/2 years.
  
  
  METHODS
  Myopia was defined as 0.25 diopter (D) or greater with high myopia as 5 D or greater.
  
  
  RESULTS
  The proportion of eyes with myopia in this preterm population was increased compared to published data on full-term children and was related to severity of both acute-phase and cicatricial-phase ROP. The percentage of eyes with myopia varied little across ages, ranging from 21.2% at 1 year to 15.7% at 4 1/2 years. The percentage of eyes with high myopia doubled from 1.8% to 3.9% between 3 months and 1 year and remained stable thereafter. The distribution of refractive errors in eyes with mild acute-phase ROP was similar to that of eyes with no ROP. In contrast, eyes with moderate or severe acute-phase ROP showed an increased prevalence of high myopia. The distribution of refractive errors changed between 3 months and 1 year with little change after 1 year. This pattern of refractive development differs from that of full-term infants. Birth weight, severity of ROP, and degree of myopia at 3 months predicted the presence of myopia and high myopia at 5 1/2 years of age.
  
  
  CONCLUSIONS
  The distribution of refractive errors in preterm infants from age 3 months to 5 1/2 years varies with severity of acute-phase ROP and cicatricial disease. Changes in refractive error distribution occur primarily between 3 months and 1 year and involve a decrease in the proportion of eyes with hyperopia and an increase in the proportion with high degrees of myopia.
authors.affiliation: Division of Pediatric Ophthalmology, Children's Hospital of Philadelphia, PA 19104, USA.
authors.forename: G E
authors.initials: GE
authors.lastname: Quinn
authors.forename: V
authors.initials: V
authors.lastname: Dobson
authors.forename: J
authors.initials: J
authors.lastname: Kivlin
authors.forename: L M
authors.initials: LM
authors.lastname: Kaufman
authors.forename: M X
authors.initials: MX
authors.lastname: Repka
authors.forename: J D
authors.initials: JD
authors.lastname: Reynolds
authors.forename: R A
authors.initials: RA
authors.lastname: Gordon
authors.forename: R J
authors.initials: RJ
authors.lastname: Hardy
authors.forename: B
authors.initials: B
authors.lastname: Tung
authors.forename: R A
authors.initials: RA
authors.lastname: Stone
mesh_terms: D000208:Acute Disease; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D017679:Cryotherapy; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D019102:Infant, Very Low Birth Weight; D009216:Myopia / Q000453:epidemiology / Q000209:etiology*; D015995:Prevalence; D011446:Prospective Studies; D012178:Retinopathy of Prematurity / Q000150:complications* / Q000601:surgery; D014481:United States / Q000453:epidemiology