AIMS

The development of simple visual acuity is most rapid in the first 1 - 3 years of life. However, the maturation of the neural pathways that refine this information and that relate visually acquired information to other systems on the brain (eg, cognitive processing, visuomotor skills including eye movements, systems of attention), in other words help one understand and react to what one sees, occurs in over a longer period and important changes are thought to occur in late childhood and teenage years.

Cerebral visual impairment (CVI) is now the commonest cause of severe sight restriction or blindness in children in the UK1and other developed countries. Less severe manifestations of CVI are increasingly described in the literature, often correlating well with lesions seen on MRI2,3 and are recognised clinically as having a major impact on child's ability to achieve their potential and extensive resources may be needed to support affected children in school and at play4-6.

Several patient groups have been described as being likely to have abnormal cerebral visual function (for example individuals born prematurely with periventricular leucomalacia4, individuals with with cerebral palsy7, hydrocephalus8, autism9 , ADHD10,11, schizophrenia12,13) but little is known about the variability in cerebral visual functions in children without identifiable pathologies, or about the pathways that lead to cerebral visual abnormalities. We have collected some data relating to development of cerebral visual functions in the ALSPAC cohort. These data include:

* Accommodation (F7, TF3)

* Stereopsis (CiF, F7, F11, TF1, TF3)

* Eye Preference (CiF, F7, F11, TF3)

* Saccadic and pursuit eye movements (CiF, F7)

* Contour detection (F7 - in a subset, F11, TF1, TF3) 14,15

* Circular contour deformation (F11, TF1, TF3) 16

* Structured history items in questionnaire sent when cohort were aged 13 years. (Questionnaire TA at 13 yr) 17

The questions asked from the "structured history" covered topics such as difficulties finding objects on a crowded background, getting lost or losing things, problems judging doorways and steps and problems seeing objects pointed out in the distance. Many relate to part of the brain known as the "dorsal stream" which comprises neurones relaying information about "where" things or the individual, are. Difficulties with these tasks can be very disabling and have been observed in children with a variety of developmental or educational problems.