Retinal morphology and function in prematurely-born children at school age

Preterm birth may lead to complications during the neonatal period that can cause visual dysfunctions. Retinopathy of prematurity (ROP) and neurological complications are well known reasons for visual dysfunctions, but preterm children with no or only mild ROP and no evident neurological problems may also be affected visually when they grow up. Retinal development starts early after gestation and continues long after birth. Major processes are underway during the second half of pregnancy when preterm children are born, and a preterm birth could possibly have a negative effect on normal retinal development. The aims of the studies were to evaluate retinal morphology and function in former preterm children and compare the results with children born at term. Former preterm children aged 5 to 17 years and born in a gestational age (GA) of 32 weeks or less were included in the different study groups. Children of similar ages who were born at term and with normal visual acuity (VA) acted as controls. Best corrected VA and refraction in cycloplegia were assessed in all children. Macular thickness and retinal nerve fiber layer (RNFL) thickness were measured with optical coherent tomography (OCT). Total retinal function was assessed with fullfield electroretinography (ffERG) and central macular function was assessed with multifocal electroretinography (mfERG). Preterm children had thicker central maculae than controls. There was a positive correlation between central macular thickness and GA at birth. RNFL thickness was reduced in the preterm children with severe ROP and treated ROP, but children with mild or no ROP did not differ from the fullterm children. The photoreceptor function measured with ffERG and the macular function measured with mfERG were reduced in the preterm group compared to controls. Preterm birth affects the retina both morphologically and functionally, and ROP has been suggested to be a reason for retinal changes. However, the results of this thesis indicate that children with no ROP also have retinal changes, suggesting an effect of prematurity itself. There were no correlations between any retinal changes and VA, but it is possible that larger studies using improved techniques may elucidate this further