PURPOSE To assess the macular thickness in 6.5-year-old children born extremely preterm (EPT) in comparison with children born at term and to investigate risk factors associated with the macular thickness in the preterm group. METHODS A population-based study of 6.5-year-old children born before the gestational age of 27 weeks and age-matched control subjects. Macular assessments with optical coherence tomography were performed, and the results were compared with neonatal risk factors and sex. RESULTS Adequate optical coherence tomography measurements were obtained from 134 children born EPT (mean gestational age of 25 weeks [range 23-26]) and 145 control subjects. The mean (range) of central macula thickness was significantly increased (P < 0.001) in the EPT group (right eyes: 282 μm [238-356], left eyes: 283 μm [229-351]), compared with the control group (right eyes: 249 μm [208-293], left eyes: 248 μm [207-290]). A multiple linear mixed model analysis of the EPT group revealed gestational age, retinopathy of prematurity, and male gender as important risk factors for an increased macular thickness. The macular thickness decreased by 3.9 μm per gestational week, when adjusted for retinopathy of prematurity and sex. CONCLUSION Extremely preterm birth constitutes a substantial risk factor for a thick central macula, even when adjusted for retinopathy of prematurity and male gender.