The optic disc and retinal vessels in children with adverse events during pre- or perinatal life

Abstract

Pre- and perinatal adverse events may cause damage to the central nervous and vascu-lar systems. The eye is an organ that allows studies of both these systems, as the optic nerve is an extension of the central nervous system, and the retinal vessels are the only vessels where direct inspection can be used for study-ing vessel morphology. The aims of this study were to evaluate the optic disc and retinal vessel morphology in children with various conditions caused by adverse events during prenatal and/or perinatal life, and to investigate whether ocular fundus morphology can reflect associated brain lesions as well as etiology and timing of the pre- and perinatal damage. Paper I describes a technique for digital image analysis of fundus photographs, which allows reliable measurements of various ocular fundus structures. In Paper II, this method was used in 100 healthy Swedish individuals of various ages from childhood to adolescence, in order to investigate the normal morphology of the optic disc and retinal vessels, thus providing reference values. In Paper III, the influence of gestational age, birth weight, perinatal morbidity and postnatal growth on ocular fundus morphology was investigated in children born preterm. There was no difference in optic disc size between the preterm children and the full-term controls. However, the preterm children demonstrated a differ-ent vascular pattern, i.e. marked tortuosity of the retinal vessels and a lower number of vascular branching points, independently of the perinatal variables studied, compared with the controls. In preterm girls, a negative relationship was found between gestational age and the size of the optic disc. In Paper IV, optic disc morphology in children with periventricular leukomalacia (PVL) was investigated. Children with PVL had morphological abnormalities, i.e. large cupping of the optic discs, and functional deficits, such as strabismus, nystagmus and visual field defects. The large cups in normal-sized discs might be a result of a transsynaptic degeneration caused by the primary lesion of the optic radiation during a sensitive period in the immature brain. In Paper V, fundus morphology in children who had been pre-natally exposed to the teratogenic substance alcohol was investigated by cross-sectional and follow-up analyses. Children with the fetal alcohol syndrome had small optic disc areas and abnormal vascu-lar patterns, abnormalities that seemed to be stationary during childhood. In Paper VI, the ocular fundus morphology and its relationship to the anterior visual pathway dimensions and midline brain anomalies were studied in several groups of children with pituitary hormone insufficiency. Morphological abnormalities, i.e. small optic discs and/or retinal vessel abnormalities, were noted in all groups. The most pronounced ocular fundus abnormalities were seen among the children with the lowest growth hormone levels. The ocular fundus findings in this group of children were associated with small anterior visual pathway dimensions and midline brain anomalies, indicating early prenatal damage. This study suggests that there is a relationship between the severity of ocular fundus abnormality and the degree of pituitary hormone insufficiency.The major conclusions of this thesis are that abnormalities of the ocular fundus occur in a number of conditions caused by adverse events during prenatal and/or perinatal life, and that the optic disc and retinal vessel morp-hology can reflect associated lesions of the brain as well as etiology and timing of the pre- and perinatal damage.