title: A methodological approach for evaluation of foveal immaturity after extremely preterm birth.
abstract: OBJECTIVE
  To characterize typical microanatomical alterations of immaturity in the fovea, that remain into childhood, after extremely preterm birth before 27 weeks gestational age (GA) and to suggest a clinical methodological evaluation tool.
  
  
  METHODS
  Subjects were consecutively recruited at age 6.5 years and organized in four groups (10 subjects in each): Group A (full-term), Group B (GA 25-27 weeks) without retinopathy of prematurity (ROP), Group B* (GA 25-27 weeks) and Group C (GA 23-24 weeks) both with ROP stage 3. Foveal microanatomy was studied using a grading system of OCT-scans.
  
  
  RESULTS
  Prematurely born children (including Group B, B* and C) had significantly reduced foveal depth (mean difference -53 μm, p < 0.001), thicker inner retinal layer (mean difference 21.6, p = 0.005) and thicker outer nuclear layer (mean difference 23.5, p < 0.001) than controls. Foveal depth and inner retinal layer thickness were significantly correlated to GA (p = 0.003 and p = 0.017 respectively) within the preterm group. Foveal depth increased with 14.1 μm per week between GA 23 and 27. The three hyper reflective bands of the outer segments as well as a central protuberance of inner and outer segment layers were present in all children.
  
  
  CONCLUSIONS
  Previous studies have revealed signs of immaturity affecting most retinal layers at time of birth in prematurely born children. The present study adds information to which extent these signs of underdevelopment remains to later in life. The applied method showed that premature birth before GA 27 weeks commonly leads to characteristic anatomical alterations of the foveal anatomy expressed as reduced foveal depth and incomplete extrusion of the inner retinal layers. Although deviations of the outer nuclear layers can be seen in the most extremely preterm born children, the outer part of the fovea generally develops well, independent of prematurity. The single most important determinant for the degree of foveal maturation seems to be GA.
authors.affiliation: Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Rebecka
authors.initials: R
authors.lastname: Rosén
authors.affiliation: Department of Ophthalmology, University of Gothenburg, Mölndal, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Sjöstrand
authors.affiliation: Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Nilsson
authors.affiliation: Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.|Astrid Lindgren Children's Hospital, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Hellgren
mesh_terms: D005260:Female; D005584:Fovea Centralis / Q000033:anatomy & histology* / Q000196:embryology; D005865:Gestational Age; D006801:Humans; D062071:Infant, Extremely Premature; D007231:Infant, Newborn; D008297:Male; D012044:Regression Analysis; D012178:Retinopathy of Prematurity / Q000175:diagnosis*; D041623:Tomography, Optical Coherence / Q000379:methods; D014792:Visual Acuity
keywords: foveal development; foveal microanatomy; gestational age; optical coherence tomography; retinopathy of prematurity