Premature birth and pregnancy to term, but with intrauterine growth restriction (often manifesting as birth small for gestational age, SGA, at term), both represent suboptimal environments for the developing infant brain and eyes. Very low birth weight (VLBW,
The aims of this study, which is part of large interdisciplinary follow up study also including cognitive, psychiatric, paediatric and motor evaluation, as well as cerebral MRI, was threefold: to examine differences in visual functions between adolescents with VLBW, or SGA at term, compared to an age matched control group to explore how detected impairments affect other functions (e.g. motor ability) to search for a cerebral correlate to the impaired visual functions, by using magnetic resonance diffusion tensor imaging (DTI).
The study shows that the VLBW group was more likely to have poor visual acuity, reduced contrast sensitivity, poor convergence, strabismus, nystagmus, anisometropia, a need for new glasses and to have started with glasses earlier than the control group. The SGA group had a slight increase in hypermetropia, but did otherwise not differ from the control group. However, none of the participants were blind or had visual acuity
Both the SGA and the VLBW group had increased risk for motor problems, but these were affected by visual ability only in the VLBW group. Risk for motor problems were reduced by 25 % by controlling for poor visual acuity, but group still remained a significant factor. Visual impairments may cause motor problems, but it is also possible that cerebral damage may be the cause of simultaneous visual and motor problems.
Finally, using DTI, a positive correlation between visual acuity and the microstructure of white matter (reflecting axonal “healthiness”) was demonstrated in the splenium part of the corpus callosum. This part of the brain is responsible for the transhemispherical relay of visual data, and is particularly prone to injury in prematurity. However, it has not been regarded as an important factor for visual acuity in prematurity before.
Premature infants are greatly at risk for perinatal cerebral injury, due to an extreme vulnerability of several cerebral systems at a crucial time, when development is particularly fast and comprehensive. This is combined with very poor ability to maintain homeostasis, causing them to suffer infections, hypoxia, unstable blood pressure, undernourishment, among others, all pathological conditions which affect the developing brain negatively.
This study confirms that adolescents with VLBW have an increased risk of visual problems. Cerebral injury probably plays a major part in causing them.