Longitudinal development of binocular visual acuity, stereopsis and global motion perception in preschool children born at risk of neonatal hypoglycaemia

Abstract

Background: Little is known about human visual development from 2 to 4.5 years of age. Even less is known about how this development may be affected by perinatal risk factors such as neonatal hypoglycaemia. Severe neonatal hypoglycaemia (a common metabolic condition in newborns) can result in injury to visual areas of the brain and impair visual development. The effect of promptly treated mild to moderate neonatal hypoglycaemia on visual development, however, has not previously been investigated. This is important, as most cases of neonatal hypoglycaemia in developed countries are mild to moderate due to early screening and treatment. Objectives: The primary aim of this study was to observe the longitudinal development of binocular visual acuity, stereopsis and global motion perception from 2 to 4.5 years of age in children born at risk of neonatal hypoglycaemia and to determine the effect of neonatal hypoglycaemia on their development. Methods: This project was a part of the Children with Hypoglycaemia and their Later Development (CHYLD) study, a longitudinal, prospective study designed to observe the effects of neonatal hypoglycaemia on the neurodevelopment of children at cross-sectional ages of 2 and 4.5 years. Age appropriate clinical tests were used to assess visual acuity and stereopsis at each age. Global motion perception was measured using optokinetic nystagmus at 2 years of age and a behavioural staircase technique at 4.5 years. All of these tests were also administered in a group of adults. The adult data were used to normalize the results from children to facilitate a comparison between tests used at 2 and 4.5 years of age. Results: There was a substantial improvement in all of the visual functions assessed from 2 to 4.5 years of age. A history of mild to moderate neonatal hypoglycaemia did not significantly affect the development of any of the visual functions measured.Conclusions: Visual acuity, stereopsis and global motion perception develop rapidly from 2 to 4.5 years of age. Mild to moderate hypoglycaemia when detected and treated early allows for the normal development of visual acuity, stereopsis and global motion perception from 2 years of age until 4.5 years of age.