OPTIMUM project, funded by a joint partnership of Fight for Sight, Royal National Institute for the Blind, Great Ormond Street Hospital Children's Charity Longitudinal study of national cohort of 100 infants with congenital visual disorders (75% disorders of the peripheral visual system) from 1 to 3 years to increase understanding of functional vision, neural aspects, cognitive, language and social development, risk and protective factors influencing outcome in development and pragmatic field trial of the impact of practitioner early intervention methods including use of the Developmental Journal for infants and young children with visual impairment. Methods include functional vision, MRI (structural, DTI), EEG, ERP, cognitive, attention, social and behaviour measures, parent-child interactions, play, practitioner records and questionnaires