Most vision impairments in children are present at birth or soon thereafter and thus greatly affect the development of the infant and interaction in the family. Children who remain at an early developmental level and children who after accident or illness fall back to a functional level of an infant require specific assessment techniques. It is incorrect to say that 'the infant is too young to be assessed'. Infants' developmental milestones are well known so a deviation from normal development can be diagnosed and the quality of vision for further development assessed.

Assessment of infants was left to be in PART III because the teaching materials are strongly based on videos and require an editing system that I could create first in fall of year 2000 with the help of Heli Ruoho who has been in charge of the technical details in editing all video sequences in the CD 'LH Materials 2001'. During the year 2000 and 2001 I have examined an increasing number of severely multihandicapped visually impaired infants and children at early developmental levels in Finland and other European countries. This is related to the interest in assessment of 'difficult-to-test children' among special teachers and therapists who often refer them for functional assessment. In their work they need more information about vision, the channel they are accustomed to use in communication during therapies and teaching. They are usually motivated to be a part of the time consuming repeated assessments and become an important part of the early intervention team.

Assessment of infants with impairments - often multiple impairments - and children at an early developmental level is more difficult than assessment of older children. Therefore it is good to have some experience of assessment techniques and a clear picture of visual pathways and brain functions in general before studying early development and intervention of infants with visual dysfunction.

In some parts of the world the word 'infant' is equal with the word 'baby', in other places it means a child at the ages between zero and three years. In this text infant is used to describe a child less than three years of age. Measurement of many visual functions of young infants is based on observations during different play and therapy situations and on only a limited number of formal tests.

Variation of the types of vision impairments in these two groups of children is great and video materials are available only of a limited number of cases. Therefore this PART III will give some ideas on how to assess and how to start early intervention, a complete textbook can be written after more experience and after development of several new test situations. The CD completed during the Comenius 3.1-Project: "Low Vision; Interdisciplinary Collaboration in Early Intervention with multiply disabled, blind and visually impaired children in Europe" is an important milestone in this work. With the information collected in it, numerous early intervention teams can enrich their assessment techniques and can in the coming years report new information that will be useful to all of us working with and for these children and their families.