title: Retinopathy of prematurity in infants weighing less than 500 grams at birth enrolled in the early treatment for retinopathy of prematurity study.
abstract: OBJECTIVE
  To describe patient characteristics, classification, and onset of prethreshold retinopathy of prematurity (ROP), and ocular findings at 6 months corrected age in infants with birth weights <500 g who were enrolled in the Early Treatment for Retinopathy of Prematurity (ETROP) Study.
  
  
  METHODS
  Multicenter randomized clinical trial.
  
  
  METHODS
  Sixty-three infants with birth weights <500 g who developed ROP and were enrolled in the ETROP Study.
  
  
  METHODS
  Infants <1251 g at birth were logged at 26 study centers from October 1, 2000, to September 30, 2002, and underwent examinations for ROP. Infants who developed ROP and whose parents/legal guardians consented were enrolled in the ETROP Study. Infants who developed high-risk prethreshold ROP were randomized; 1 eye was treated early with peripheral retinal ablation and the other eye was managed conventionally, or, in asymmetric cases, the high-risk eye was randomized to early peripheral retinal ablation or conventional management. All eyes reaching prethreshold ROP were examined when infants reached 6 months corrected age.
  
  
  METHODS
  Retinopathy of prematurity incidence, characteristics, and ocular findings among participants.
  
  
  RESULTS
  Thirty-four infants reached prethreshold or worse severity in 1 or both eyes. Retinopathy of prematurity was located in zone I in 43.3% of all prethreshold eyes, and plus disease was present in 46.7%. Median postmenstrual age for diagnosis of all prethreshold ROP was 36.1 weeks, but earlier (35.1 weeks) for eyes that developed high-risk prethreshold ROP. In the 27 surviving infants with prethreshold ROP, ophthalmic examination at 6 months corrected age showed a normal posterior pole in 22 (81.5%), a favorable structural outcome with posterior pole abnormalities in 4 (14.8%), and an unfavorable structural outcome (stage 4B) in 1 (3.7%). One infant developed amblyopia, 4 infants developed nystagmus, 4 infants developed strabismus, and 8 infants developed myopia >-5.00 diopters.
  
  
  CONCLUSIONS
  This is the first report on characteristics of prethreshold ROP in infants with birth weights <500 g. These infants are at high risk for developing prethreshold ROP, although many initially achieve a favorable structural outcome. They are at risk of developing strabismus, nystagmus, high myopia, and abnormal retinal structure and should therefore receive continued long-term follow-up.
  
  
  BACKGROUND
  The author(s) have no proprietary or commercial interest in any materials discussed in this article.
authors.affiliation: Casey Eye Institute, Oregon Health & Science University, Portland, Oregon 97035, USA. david.wheeler.md@gmail.com
authors.forename: David T
authors.initials: DT
authors.lastname: Wheeler
authors.forename: Velma
authors.initials: V
authors.lastname: Dobson
authors.forename: Michael F
authors.initials: MF
authors.lastname: Chiang
authors.forename: Don L
authors.initials: DL
authors.lastname: Bremer
authors.forename: Ira H
authors.initials: IH
authors.lastname: Gewolb
authors.forename: Dale L
authors.initials: DL
authors.lastname: Phelps
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Hardy
authors.forename: William V
authors.initials: WV
authors.lastname: Good
authors.forename: Rae
authors.initials: R
authors.lastname: Fellows
authors.forename: Betty P
authors.initials: BP
authors.lastname: Tung
authors.forename: Earl A
authors.initials: EA
authors.lastname: Palmer
mesh_terms: D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D052577:Infant, Extremely Low Birth Weight; D007231:Infant, Newborn; D053685:Laser Therapy / Q000379:methods*; D008297:Male; D009887:Ophthalmoscopy; D012160:Retina / Q000473:pathology*; D012178:Retinopathy of Prematurity / Q000175:diagnosis / Q000601:surgery*; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D014792:Visual Acuity