Multihandicapped children are a challenge in medical diagnostic examinations. Communication is often so complicated and highly individual that most sign language interpreters cannot help us. The caregivers, parents and teachers are the persons who know how to ask questions and how to interpret responses. So our approach in examining the multihandicapped children is very different from our usual clinical work: instead of examining most of the functions ourselves we now become team leaders and execute the test situations through other persons.

Deafblind children with multiple impairments often have had viral or bacterial infections involving brain tissue, optic and auditory nerves. If the infection was intrauterine, as rubella, there are often changes in the end organs themselves. Because of the diffuse involvement of brain tissue, additional impairments show a multitude of unusual sensory and motor functions. Since many of these children are diagnosed late, that is, the dual sensory impairment is recognized after the age of 3-4 months, deprivation syndrome adds its negative influence on the total development of the child.

Rubella infants are often seriously ill for months, and they may need several surgical procedures and extended hospitalization. All these factors complicate the development of the infant, decrease early interaction between parents and the infant, and also complicate the assessment of vision and its potential use.

Children with other syndromes that include visual and auditory impairment may also have complex neurologic impairments that make the assessment of their vision difficult.

Assessment of vision is usually divided into three parts:

1. basic objective examination by the doctor,
2. observation of visual function in planned play situations,
3. training for and execution of formal test situations.

Observations during play situations are usually recorded on video film for further analysis by the team, because the child can seldom function at his optimal level when the ophthalmologist happens to visit the institution or hospital ward. In fact, these children almost never function at their optimal level during office visits. Sometimes I arrange for an appointment on a Saturday morning when the office is closed and ask the family to come with the child's favorite toys and foods some two to three hours before the examination, which is planned for the child's optimal time during the day. Since there are no other patients, I can start the examination at any time when the parents report to the receptionist that the child seems to feel comfortable. A major part of the examination often takes place in the waiting area.

During the basic examination it is often possible to get a general idea of the restrictions in the use of vision, the need for refractive correction, and to make a plan for observational situations and tests that should be used later. In making the plan there are several steps that should be considered:

1. The developmental level of the child: whether his actions are age-appropriate or lower, and whether the profile of different developmental abilities is smooth or ragged. If the description of the child's prior level of functioning differs notably from that seen during the first examination, a reason for this should be found.

   The overall cognitive level of the child helps determine the level of difficulty of the tests used. For example, in the measurement of visual acuity the child may be: below optotype tests (0-18 months) single optotypes (18-36 months) simple line tests (3-5 years) usual line tests ( > 5 years)

2. Communication problems are common in vision tests. They may be related to:
   visual impairment and hearing impairment
   impaired auditory and/or visual processing
   motor problems in signing or speech
   dysphasia, aphasia
   minimal seizures
   autistic, psychotic features
   short attention span
   short memory span
   The level and type of communication during the tests should match the child's best mastered communication.

3. The effect of posture may be important. Therefore, the different visual functions should be observed in at least the six cardinal postures:
   lying on back
   lying on stomach upright, either sitting alone, or
   sitting supported, or
   sitting with an adult, or
   standing, supported.

   An often effective, half-upright posture is holding the child in a resting position against an adult's shoulder. The changes in the child's visual functions in these different postures can be carefully recorded and reported to the special educator, so that the information can be used when planning play situations.

4. An optimal activity level should be created. Visually impaired children typically function at a low general activity level because of the scanty visual stimulation from the environment. When auditory information is also absent the child is understimulated even more. In order to bring visual functions to an optimal level, we may need stimulation through gross motor activities, vestibular stimulation, or any other intervention that activates the child.

   Hyperactive children must first calm down and relax before they can perform in the test situation. It requires both creativity and flexibility to adapt the examination to fit the optimal play situation of a hyperactive child.

5. In several eye disorders, luminance level affects the outcome of the test situation. If there is any uncertainty about the most favourable luminance level, a fair number of observations should be made at low, intermediate, and high luminance levels.

6. When we teach the members of our team about observation techniques, it is important to stress that there are several preprequisites for looking. The child must be able:
   to be motivated
   to attend
   to direct gaze
   to adjust accommodation
   to fixate and follow a target.

   One or several of these brain functions may be poorly developed. Also, because these children have a loss of function in different parts of the visual field, their fixation pattern may be confusing. The usual central fixation may be stable or the child may have nystagmus. Children with central scotomas use extrafoveal viewing and seem to look past, and not at the object. Autistic children may avoid fixating on objects that they know the adult would like them to look at.

The responses of these children and adults may be greatly delayed and difficult to notice. In this communication an interpreter of the deafblind is usually not the best person to help; the special educators and parents usually can interpret the reactions best. The response pattern of a given child becomes known over a period of time. An assessment may require weeks or months of observation, a combination of several persons' opinions and an analysis of several hours of video films. Quite often the first impression is found to be erroneous, so we have to be prepared to accept corrections.

The persons involved in the assessment vary in different settings. Usually an ophthalmologist needs the help of an audiologist, a paediatrician (or preferably a paediatric neurologist), an optometrist (where they are available), a neuropsychologist, several special educators and of course the primary caregivers. It takes time and effort to create such a team for the careful assessment of vision, but it is the only way of gaining a reliable picture of the visual functions of multiply handicapped children.

Presently, the assessment of functional vision is in the hands of special educators, and it will continue to be so in the future. Since the assessment is complicated by additional neurological impairments, the team approach in the analysis of the observations will improve the quality of the functional diagnosis.