title: Refraction and visual acuity in a national Danish cohort of 4-year-old children of extremely preterm delivery.
abstract: OBJECTIVE
  A recent threefold increase in laser treatment for advanced retinopathy of prematurity (ROP) triggered a nationwide preschool ophthalmic and developmental status among extremely preterm survivors. Here, we discuss refraction and visual acuity.
  
  
  METHODS
  Survivors (n = 178) from a national birth cohort (February 2004 to March 2006) of gestational age <28 weeks (PT) and 56 full-term (FT) controls attended for evaluation at age 4 years. Cycloplegic refraction and keratometry were achieved by Retinomax autokeratorefractor and visual acuities by symbol recognition (HOTV, logMAR).
  
  
  RESULTS
  The refractive distribution presented a myopic tail (4.5%) and a hyperopic tail (11.9% ≥+2.5 D) as special preterm features, and corneas were more curved. Astigmatism and anisometropia were only marginally increased, and visual acuities were generally good. Best-corrected binocular median logMAR visual acuity was 0.1 in FT and 0.2 in PT, in Snellen equivalents 0.8 and 0.63. Snellen acuity ≤0.5 occurred across the ROP subgroups, but mainly in those with at least ROP stage 3. Two children had low vision.
  
  
  CONCLUSIONS
  The overall fair outcome for refraction and function is in accordance with other recent northern Europe experience. The results differ in particular from the poorer ophthalmic outcomes reported in the pioneer US treatment studies (cryotherapy for ROP and ETROP). The diode laser ablations (n = 32) appeared effective in our series; except one child, all treated subjects had good or fair social vision at the age of 4 years.
authors.affiliation: Copenhagen University Eye Departments, Glostrup Hospital & Rigshospitalet, Copenhagen, Region Hovedstaden, Denmark.
authors.forename: Hans C
authors.initials: HC
authors.lastname: Fledelius
authors.affiliation: Copenhagen University Eye Departments, Glostrup Hospital & Rigshospitalet, Copenhagen, Region Hovedstaden, Denmark.
authors.forename: Regitze
authors.initials: R
authors.lastname: Bangsgaard
authors.affiliation: Copenhagen University Eye Departments, Glostrup Hospital & Rigshospitalet, Copenhagen, Region Hovedstaden, Denmark.
authors.forename: Carina
authors.initials: C
authors.lastname: Slidsborg
authors.affiliation: Copenhagen University Eye Departments, Glostrup Hospital & Rigshospitalet, Copenhagen, Region Hovedstaden, Denmark.
authors.forename: Morten
authors.initials: M
authors.lastname: laCour
mesh_terms: D001251:Astigmatism / Q000175:diagnosis; D002675:Child, Preschool; D003718:Denmark; D005260:Female; D005865:Gestational Age; D006801:Humans; D062071:Infant, Extremely Premature; D017075:Laser Coagulation; D008297:Male; D009184:Mydriatics / Q000008:administration & dosage; D009216:Myopia / Q000175:diagnosis; D012029:Refraction, Ocular / Q000502:physiology*; D012178:Retinopathy of Prematurity / Q000503:physiopathology / Q000601:surgery*; D042262:Retinoscopy; D014792:Visual Acuity / Q000502:physiology*
chemical_list: D009184:Mydriatics
keywords: emmetropization; immaturity; keratometry; myopia of prematurity; preterm cohort aged 4 years; refraction; visual outcome