title: Distribution of macular thickness by optical coherence tomography: findings from a population-based study of 6-year-old children.
abstract: OBJECTIVE
  To study the distribution of macular thickness by ocular and demographic variables in a population-based study of young children.
  
  
  METHODS
  The Sydney Childhood Eye Study examined 1765 6-year-old children from 34 randomly selected Sydney schools during 2003 and 2004 (78.9% response). A comprehensive eye examination included cycloplegic autorefraction and optical biometry. Fast macular thickness scans were performed over a 6-mm diameter central retinal region with optical coherence tomography. Multivariate analyses were performed. Macular thickness is presented on a modified Early Treatment Diabetic Retinopathy Study (ETDRS) macular grid, with outer radii for the central, inner, and outer macular regions being 0.5, 1.5, and 3 mm, respectively.
  
  
  RESULTS
  In the study, 1543 children (88.7% of participants; 51.1% boys) had high-quality scan data (mean age, 6.7 years). The mean (SD) minimum foveal thickness was 161.1 (19.4) microm. The thickness of the central, inner, and outer macula was normally distributed, with means (SD) of 193.6 (17.9), 264.3 (15.2), and 236.9 (13.6) microm, respectively. Total macular volume was also normally distributed, with a mean (SD) of 6.9 (0.4) mm(3). The temporal quadrant was thinner than other quadrants for both inner and outer macular regions. The foveal minimum, central, and inner macula was generally significantly thicker in boys than in girls, and in white than in East Asian children. Outer macular thickness showed no significant gender-ethnic differences. Sectoral macular thickness variations were preserved in both gender and ethnic groups. The inner and outer macula, but not the central macula, showed significant thinning with increasing axial length. These corresponding areas were significantly thicker with more hyperopic spherical equivalent refractions.
  
  
  CONCLUSIONS
  Macular thickness and volume were normally distributed in this young childhood population. Significant gender and ethnic differences were demonstrated. Axial length and refraction were important ocular biometric determinants of macular thickness.
authors.affiliation: Department of Ophthalmology, the University of Sydney and the Centre for Vision Research, Westmead Millennium Institute, Westmead Hospital, Sydney, Australia.
authors.forename: Son C
authors.initials: SC
authors.lastname: Huynh
authors.forename: Xiu Ying
authors.initials: XY
authors.lastname: Wang
authors.forename: Elena
authors.initials: E
authors.lastname: Rochtchina
authors.forename: Paul
authors.initials: P
authors.lastname: Mitchell
mesh_terms: D019412:Anatomy, Cross-Sectional; D002648:Child; D005006:Ethnicity; D005260:Female; D006801:Humans; D008266:Macula Lutea / Q000033:anatomy & histology*; D008297:Male; D009517:New South Wales; D044382:Population Groups; D012737:Sex Factors; D041623:Tomography, Optical Coherence / Q000379:methods*