University of Edinburgh

Vision for Doing

Assessing Functional Vision of Learners who are Multiply Disabled

Chapter 7 Assessing Vision for Doing

Section 9 Learner's Responses to Light

Aims of section 9

This is the first of several sections in which you begin to use tools and techniques to assess what the learner actually does see. Turn to the items listed on the left hand side of the page. They are set out in a certain order. Beginning with a strong visual stimulus, they travel down with the visual stimulus becoming weaker. None of the items could be said to investigate whether and how the learner sees real objects.

Sunlight, daylight and the other items are mostly just different levels of illumination. Normally they would only be considered in our world as a means to an end. For without some combination of them in our world there would be little chance of seeing the objects and events of that world. A person who could see only one or more of these items would certainly be classed as blind. As we will find out shortly, however, there are several techniques that could still be tried with learners functioning at this level: not a great number but indeed a help

How to use

section 9

Of course you may not have some of the materials available (in Scotland especially you might have to wait rather a long time for sunlight!). If this is the case, skip that item. If you find that the item below is checked (tick Consistently), then you can assume that, had the right materials been available, the missing item would probably have been checked.


It is easy to improvise in this section. For example, turn the learner around in her wheel chair to change the direction of light source, or open and close blinds or curtains in a room. Different kinds of response may be observed. For instance it may be that, irrespective of the location of the light source, the learner simply closes her eyes or blinks. Or if she can work out the direction of the light source, her eyes may be directed quickly to the light. It may then be possible to reduce the intensity of the bulbs used.

Cautionary Note

Remember not to allow previous stimuli used to influence subsequent items. So don't try using torchlight while the sunlight is still shining in the same area. Not only would you be making the item more difficult, more importantly, the learner might not detect the new item (torchlight) but still be responding to a previous item (sunlight). Because there is a response you would conclude wrongly that the response is to the new item.

Transferring results to Section 18

Refer to the checklist at the start of this section. Now you have to decide what the results of your observations mean for the purposes of curriculum development. You have to decide which boxes to tick in the Summary Chart (in Section 18). In that Summary Chart you will find that in the row for Section 9 there is only space to tick under Aware and Attend. The other three boxes are filled in. This is because any general response by the learner to light cannot tell us very much.

If, however, the learner makes a very specific response (eg; reaching out accurately to a torchlight) this would tell you that the learner could Localise. If the learner could also name it then that in turn would tell you even more. Naming would mean he could Recognise through vision. The point is that additional information will be needed if you are to know that the learner is doing more than Attending. If you have that kind of extra information by all means tick boxes in the shaded areas of Section 18, as appropriate.

No response to light?

If the learner Never shows any visual response to any of the items in this section, you should also not be able to observe any visual responses to any of the subsequent sections in this Chapter. A learner has to show some response to gross changes in lights in order to be able to have some visual function. If you are in any doubt, come back another day and try again.1.

Score Attend if:

Your observations indicate the learner responds Consistently to "sunlight", "daylight", "room light" and "torchlight:. If so, go to the Summary Chart find the row for Section 9 'Responses to Light' and put a in the box for Attending. Then move on to Section 10 (Learner's Responses to Reflected Light). It is unlikely that you find the curriculum suggestions in Section 9 of much benefit.

If the learner responds Consistently to "Learner Light Gazes" also tick Attend in the Summary Chart and move on to the next section.

Or score Aware if:

The learner responds Consistently to "sunlight", "daylight", and "room light", but does not respond Consistently to "torchlight". If so, tick Aware in the Summary Chart. Then move on to Section 10. In this case you may well want to return and use the curriculum suggestions given in Section 9.

If the learner responds Occasionally to "sunlight", "daylight" and "room light", also tick Aware in the Summary Chart. Do not tick Attend. Again you would want to make use of the curriculum suggestions given in this section.


If the learner actively avoids lights, you should still tick Attend in Section 18. You may find that very low levels of illumination are appropriate. Using different Settings (changing levels of light, changing angles of light, going to different areas, asking other people), try to discover the optimum lighting conditions.

Where to go now?

Having noted the results of your observations and transferred these to the Summary Chart, you are then ready to make a choice. The choice you make will depend on the results you obtained.


You can skip the remainder of this section and proceed directly to Section 10 dealing with assessment of vision. By doing this you will continue your assessment of the learner's use of vision.


Postpone further assessment and read the remainder of this section. In it we suggest activities for curriculum development. These are to do with the use of light.

Developing a curriculum

Improving awareness:

For you to have an interest in this subject, you will have found from the completed Summary Chart that the learner is only Aware. Vision will be limited to perception of various forms of light. Similarly the learner's use of 'The Other Senses' will be functioning at the level of Awareness. Those most interested in this part of Section 4 will be working with people who have the most severe difficulties in learning about the world. Responses to information detected through sound, touch, smell and taste will, like those to visual information, seem to be inconsistent or even totally absent. They will only occur at this fairly gross level. Of course you would not only be interested in carrying out the activities of this section. You might also want to include some of the techniques mentioned in Chapter 6 which deals with non-visual information. Here we deal with aspects relevant to making use of only very limited vision.

The first thing to do is to look at your own response to the first item of Section 2. If you answered something to the question ">The Learner has preferences", you need to ask the following question. How is it you know the learner likes something but it is so difficult to elicit any response to events in the world? For in order for him to show he likes something he needed to respond to something consistently. Was it a smell? Some tactile material? Or other? Whatever it is, it can be worked with. Now for some specific activities which you can try.

Watch to see whether the learner turns away from or towards the light, or perhaps reaches for it. This can be used to add to observations of responses to different positions of objects in the field of vision (Section 13).


Try to improve awareness of the relationship between a slight movement by the learner and its effect. Decide on a movement made by the learner that you will use. As the learner is functioning at Awareness then the chances are that the movement will be slight. It may be movement of a hand that appears on occasion or a head movement, or even an eye movement (though you should not use eye movements if in Section 8 you checked the item asking if there were unusual eye movements). The movement you select may appear random.

You are going to try to link movement with a light being switched on Immediately the movement is made. So the order is:

movement - light on - wait - light off

Before starting there are a couple of other things to note.

Position the light at the same side as the direction of the learner's movement. Have the light on for about the same length of time as the movement is made, or a little longer. If there seems to be no movement try passively lifting the learner's arm or hand before switching on the light. (It helps if you have a tame octopus handy). Appendix I gives additional information on using Switches and Interfaces.

Light with sound

Most of the activities we have described which make use of light can profitably be used in conjunction with other non-visual stimuli. For instance, one routine might be to associate the movement with various musical rhythms as well as a light being switched on. This would be similar in some respects to that which occurs in music and movement therapy sessions. The best of these types of sessions occurs when it is the learner who has to make a movement in order to start the musical rhythm. Where there is no active movement, one can begin with movements made passively on the learner. For instance, a leg might be lifted, while simultaneously switching on a tape recorder, following this by moving the leg or foot in rhythm with the music produced by the tape recorder. Often you will have to put up with the most awful taste in music2.

Where there is some success, try to identify if there is a pattern to the music liked by the learner. Is it perhaps associated with parental preferences, or other pleasant activities? Do regular rhythms and strong beats help? Does repetitiveness help?


If touching or tickling some part of the body appears to give pleasure, then this can be used in association with a light source. Suppose that his/her foot curls on being tickled. Tickle the foot and shortly after switch on the light. Do this a few times. Then stop tickling but switch on the light. Does the foot curl? If so, you have managed to associate one event with another. Learning has taken place.

You can use this to try to move from Awareness to Attending. By changing the position of the light source to correspond with a different site of the body (eg; the other foot), you can note whether the new site of the light is responded to.

Raspberries to you

Now for a game of raspberry blowing for the learner who does not seem to make any connection between what he does and something happening in the world. Pair a light source (or combine this with sound and smell stimulus), with blowing a raspberry on a part of the child's body. Make the pairing very close together in time. If there is any change noticed in using this approach then you would have the opportunity to begin the kind of environmental control that we discuss below.

Using technology

Don't be frightened of this part, as we are only going to move slightly away from what you were doing with the light switch. Nowadays any part of the body which is under voluntary control can be turned into an effective controller of the environment.

The principle underlying this is exactly the same as the one we used with the light switch. (And of course the principle of control was one of our central commandments of intervention outlined in Chapter 4). There are many examples of using technology with learners who have visual and additional disabilities, such as a footkick activating a switch which in turn operates a light and tape recorder or a Pethna box.

Switches offer one way of controlling some aspects of the environment. Modern technology using microchips as the basis of switches has introduced excellent ways for increasing control of the environment. However there is a price to pay in using new technology.

Switches: a word to the wise

We have already encountered one difficulty: that is how to establish whether a movement is voluntary. Technology can help in this process because a movement activating a switch can have an immediate effect, and an effect that is consistent. Switches may be effected through blowing and sucking, eye movement, head pointing to a target, ear wiggling, not to mention foot kicking and other more conventional means of operation. Unfortunately, the use of this technology is not always carried out in a principled fashion. Consider a learner lifting his arm. This action operates a switch which turns on a light source. Seems simple enough, until one considers the learning involved, which may make this task difficult. Here are some questions to consider.

Should the event (light switch on) occur immediately the arm is moved? In which direction is the arm movement to occur?

Will the event occur on the same side as the learner's arm or the middle or the opposite side, above or below? Should the light be bright or dim, coloured or white? For how long should the light be activated? What if the learner lowers his arm, should the light stay on or go off with the lowering. Should every arm raise result in the light being activated, if not how often should they occur? Should it always be the same light in the same position relative to the learner? Is it best to have a switch which is latched, or some other?. (see Appendix I for explanation of the meaning of 'latched'.) The answer to each of these will present different levels of difficulty to a learner, and an answer will depend on what his previous experience of similar and different activities have been. Consideration of the criteria we outlined earlier will give a 'best bets' for proceeding with this kind of activity. (For those who are interested in taking this further we have provided a more in-depth discussion of 'switching' in Appendix I).

Let us spend a little time on a special kind of technology which can be used with learners who have multiple disability. Computers offer another means of developing curriculum opportunities for learners who are only Aware of light.

How many times have you heard that some or other multiply disabled person is ">On the computer". Perhaps you might think this sounds a bit like being 'on the toilet'. Despite this rather negative view, use of computers can nonetheless be a helpful way of harnessing technology in order to extend curriculum opportunities for those who are multiply disabled. If you are unsure of the pros and cons of using computers in this way you may wish to read Appendix II. Here we will concentrate on specific ways of using computers with learners functioning at this 'stage'.

Useful software

Using a computer with a person who has this low level of vision takes advantage of the fact that the screen has its own light. Being backlit (as it is termed) means that the learner is never in his or her own shadow. So the amount of illumination is not reduced. If you have followed our central principles (Chapter 4) you will be wary of software of the type that simply presents a coloured screen totally outwith the learner's control. Instead look for software that can be controlled by switch input. Even better is software that allows you to change when a switch being hit causes a screen effect3.

Using a "dark room"

Although these guidelines are designed to be used with the minimum of equipment, some schools have 'dark rooms' or suitable cupboards and staff may be wondering about the most efficient way of making use of such facilities in encouraging use of vision.

Working in a darkened environment with light can make it easier both for the pupil to become aware of a particular stimulus and for the person presenting the stimulus to notice any response. People who seem to have normal eyes and yet no obvious visual response are sometimes referred to as having cortical blindness or cortical visual impairment. It is thought that their difficulties are perceptual in kind, which means they have difficulty in picking out individual characteristics and recognising the same characteristics on different occasions.

To illustrate what is meant by 'cortical blindness', consider a baby becoming familiar with a feeding bottle. The first time the bottle is presented the baby will respond to the teat being put in her mouth and chew to suck. Gradually, through seeing this same object appearing at regular intervals when hunger pangs are felt, and combining the sight of its shape, colour, feel, warmth, smell and the taste of what it contains, it becomes recognised as 'my bottle'. For the learner with cortical visual impairment recognition of these features can be a long slow process.

Perception of light is the most basic of visual perceptions and without it no other vision can develop. If the learner appears not to be seeing, try to get a response using lights. In a normally-lit environment it may be very difficult to pick out or perceive a small light source, even when it is moving. Light does not have the additional characteristics of objects, ie; three dimensions, feel, smell, taste, and in order to use its properties more effectively we need to make it stand out.

A dark room can help greatly with this. Even a penlight torch seems so much brighter in darkened surroundings. Reflective objects placed in front and to the side of the learner can be picked out by torchlight of different colours starting with the primary colours of red, green, blue, yellow as well as white. Larger light sources such as overhead projectors or slide projectors can be used with coloured acetate + home-made patterns which can be projected onto the wall in front of the learner. The learner's position can be varied to near or far, and the pattern can be put in and out of focus. The only drawback is that these machines are noisy and attention may be drawn more to the sound of the fan than to light on the wall. Sometimes, just the fact of being in a different environment makes the learner more alert, interested and inquisitive.

Ultraviolet (UV) or black light

The use of this light is a little more controversial. Some medical sources claim that over-exposure to this form of light can carry some risks. Your Local Authority may well have a ruling on this and it would therefore be important to consult its Health and Safety regulations.

Among major considerations are that the light may have to be deflected, mounted on a wall with the cornice directed upwards. Another option is to use a 'light box'.

Among staff in school who use UV light, care is generally taken to ensure that it is not just one member of the staff who becomes the 'UV person', but that members of staff will take turns or work with their own pupils for this activity.

Taking into account learner's awareness or concentration span, 10 minutes several times a week would not be threatening. The whole idea with UV light is to give the person a 'kick start' along the continuum of vision and therefore, ideally, its use should not be long-term. Why can UV light be such a potent tool in 'alerting' a learner to the visual environment? It is because fluorescent or phosphorescent colours seen under UV light are many times brighter than other colours. Another advantage is that real objects can be used and the learners own body can be picked out with fluorescent strips or paints so that there can be development in hand-eye coordination, awareness of moving body parts, awareness of colour, shape and size, tracking and visual fields. Tasks ranging from self help skills to games can be carried out under UV light if the visual components can be picked out in fluorescent paint or made of fluorescent materials.

As with all other compensatory approaches the sooner the skills developed under UV light in the dark room can be translated to the normal environment of class or home the better. After all most of our life has to be lived in places with only normal illumination.


Several of the techniques and activities we suggested on "Improving Awareness" will also apply to this subject. In addition to these you may wish to use the following suggestions.

For those who have some limited mobility, a bright or fluorescent object can be presented in subdued lighting a few feet away, thus encouraging the learner to crawl, creep, shuffle, or walk towards that object. As with the section on the use of a dark room with fluorescent lighting, it is often better to use more than one object. This is because of the existence of what is known as the autokinetic effect4.

In some cases a learner may seem not to be attending visually, even though he or she might well be. This usually happens because the learner cannot direct his eyes towards the light or reflecting surface. When looking at this behaviour, note then whether the learner, although not looking towards the light source, is looking consistently in another direction. We have already met this apparent aversion of the eyes when we discussed compensatory head movements (in Section 3)

Use a variety of lights, varying paper colours and thicknesses as filters. The room can be darkened too, as this will accentuate any contrast differences. If you have not already managed to discover the optimum position for the learner, this would be a good time to experiment. You may be able to enlist the help of a physio or occupational therapist for this task. Try to determine the best position for the learner being aware of light.

(NB When using a light close to the learner, ensure that there is a cover between the learner and the light to reduce the chance of a possible accident - a sheet of clear plexiglass is ideal).

Attending and mobility

As you may well appreciate, a learner's physical abilities may be impaired further by visual defect. Many writers have shown that crawling, walking, sitting, standing, reaching, and head-turning - to name but a few - may each be delayed or impaired in the learner with a sight problem. Standard approaches of physiotherapy may exacerbate rather than improve the problem. For example the young learner who is slow to walk may be prescribed a baby walker. This can often do more harm than good. While having the advantages of strengthening the legs and moving the feet, the learner with a visual impairment is in other respects disadvantaged. Without vision to guide the learner, he is likely to produce lunging movements, often to the side rather than to the front. He may move on tiptoe, exaggerating the problem of maintaining balance. Proprioceptive information is weak, and balance then becomes impaired. A simple change is to add a consistent light source to which the learner may attend.

Cortical visual Impairment/ blindness

We would like at this point to discuss a condition mentioned earlier.

Many learners who have multiple disability, have eyes which look perfectly normal, they move together, there is no squint, they seem to fix steadily. Both parents and professionals find it difficult to reconcile these apparently normal visual behaviours with the learner being registered blind. The reason is that the messages reaching the brain from the eyes are not being properly interpreted. Sometimes this is given the name 'cortical visual impairment or blindness' or 'cerebral visual dysfunction'.

Where CVI is found

During almost every visit we made to schools and other centres in which there were learners with multiple disability, we were asked the meaning of 'cortical blindness'. Before considering its meaning, and why we prefer to use the term cortical visual impairment, it might be appropriate to reflect on why it is that the question was posed so often. Why are there so many learners with CVI in centres for learners with the most severe disabilities?

Why is CVI found there?

Within schools which have learners with the most severe disabilities, a substantial number of children will have considerable brain damage, or disorders of the central nervous system. The eyes have, through evolution, become an extension of the brain providing us with one means of obtaining information about distance. Because the brain also has to interpret the information received through the eyes, any damage to the area of the brain which does this interpreting will mean that this too will be affected. Typically the eyes of a learner with cortical visual impairment (CVI) may appear normal (though they also may not). Shining a light into the pupils may result in the pupils changing size, they may (or may not) move in synchrony. Information may travel along the optic nerve to the brain, but it is as if the telephone exchange has been disconnected: the phone was working but the call never got to its destination.

CVI and other disabilities

It is very unusual for a learner with CVI not to have additional impairments, most do. In fact, in a study of this condition carried out in British Columbia, out of 123 learners diagnosed as having CVI, only one had no additional disability. By converse, where there are children who have several disabilities, it is more likely to find some who have CVI5.

For the majority of learners with CVI, it is congenital or acquired within the first year of life. Most common causes are asphyxia, developmental brain defects, injury and infection. Accompanying neurological impairments are likely to be 'mental retardation, cerebral palsy, epilepsy, hydrocephalus and deafness' (Groenveld et al 1988). A visual impairment located in the eye itself may also be present, the most common being optic atrophy, These learners may also have refractive errors which will need correction by lenses.

Effects of CVI

The range of visual disorder varies. Some learners with CVI seem not even to have light perception, while others can perceive light and large objects. Improvement in visual functioning may take place over a period of years (Warburg 1983) and (Groenveld et al 1988). In some cases the level of visual functioning may be related to the learner's developmental level and improve as progress is made. Therefore each case ought to be considered individually. Some of its other effects include the following:-

  • total blindness;
  • upper or lower half of the visual field in both eyes not working- anything presented in the affected half might not be seen;
  • one quarter of the visual field not working;
  • holes in the visual field like a Swiss cheese;
  • there may be difficulties in perception of an object from its background or, even more likely, a difficulty in perceiving the nature of a picture or photograph;
  • there may be other difficulties in putting together or organising parts of an object;
  • although able to see one object, after another is brought in, the first one "disappears";
  • inability to recognise faces, although able to see them.

The list is by no means exhaustive, and is presented to give some idea of the problems which may be manifested with CVI.

What to do?

Because this book is concerned with the effects of visual impairment, then the strategies offered are relevant and can be applied to those learners with CVI. Most of the strategies for intervention will therefore be presented as appropriate in the relevant sections of this chapter. There are, though, a few general points to be noted.

Effective positioning

The discussion presented on appropriate positioning of the learner is especially important for those with sitting or hand control difficulties. Otherwise they will use energy in keeping their balance, or 'lose' their target involuntarily. If securely supported, this will help in visual tasks. This means that it is important for teachers and/or care-givers to analyse the aim of the activity. Able learners can tackle a task with several separate parts, but learners with CVl may only be able to cope with one demand at a time so it may be counter-productive to try and combine a physical exercise with a visual activity.

Make it simple

As well as avoiding complexity in the number of tasks demanded, complexity of the visual information should be kept to a minimum. It often helps to introduce the object both visually and tactually, before using it for assessing vision.

Blocking lights

At this point try introducing objects to block out light sources. In this way you will be moving away from an emphasis on simply the level of illumination.


How can there be a possibility of Localising if Section 9 only allows you to tick Aware and Attend? The reason is of course that the Summary Chart may indicate that although vision is severely limited, 'The Other Senses' suggest higher level functioning. That being the case here are a few suggestions relevant to those who function generally at Localising but have severely limited vision.

Anchor points

Where you find even limited response to sunlight and daylight this can still be used in many ways. You could use this to increase understanding of position in a room. If the light source is used as a consistent point of reference there is increased opportunity to anticipate the direction in which objects and activities will be met. This consistent point of reference - often known as 'anchor points' - is important for those with severe visual impairment. Without one it becomes difficult to gain confidence to step out independently. How would you feel about taking a step when you were uncertain whether you might fall down a hole, or hit a door or a wall?

Anchor points increase opportunities for mobility (independent mobility can also occur in a wheelchair of course). However there is one important point about the facility of sunlight as an anchor point: don't forget that the sun moves and its presence is not very reliable!


You will probably not need to do anything special to know the outcome of this item. It is the kind of everyday knowledge you will already have gained about the learner. A consistent (Always) response to this item is especially helpful in being able to take forward the notion of giving points of reference. Daylight at one window will have an anchoring relationship to the door entry into a room.

Passive movement

To improve on the visual capture of an object just prior to a reach/grasp, assist him to follow the object passively while placing his hand on that object. It can be moved to a new location as soon as the object is centred by his vision. It may be illuminated, by for example using a small pen torch inside a coloured brick, cup or similar object. If this does not work try brighter illumination (eg; a bigger torch). Change to using different coloured thin materials as filters.

Using light for mobility

For the young visually impaired learner, trundle truck types of walkers offer a better chance for establishing independent mobility than the makes of babywalker in which the learner is seated. Another idea used successfully has been to use a small rollator at the front of which is attached a torch, pen torch or one of these covered by the colour of 'filter' that was found to be most effective in the above paragraph 5 in the UK, Targets can be obtained from NW SEMERC or RCEVH (addresses in Appendix II).

Too much emphasis on the physical aspects of mobility often stress unnecessarily the confrontational nature of activities. By emphasising game-playing, essentially physical movements and positioning become secondary.

Dark room

The suggestions given in the previous topic ("Improving Attending") on use of a darkened room also apply here.

Use of computer

Because of such limited visual functioning you will need to ensure that the level of illumination in the room is reduced. This allows the screen to be a relatively powerful stimulus. Use of software such as Targets will require large shapes to be presented. Even when this is coupled with a Touch Screen, however, the degree of understanding required may mean you do not observe the learner carrying out the game himself. Nevertheless the changes in position of the target shapes on screen will be a useful way of increasing chances of recognition.

You can also monitor whether one or more shapes are beginning to be recognised. Do this by observing how quickly the learner gets bored with one shape. Do this by counting the number of presentations, noting this number. For each presentation see for how long the learner finds it interesting. Then change the shape on screen. Is attention regained? If so, for how long?

There are many variations on this and you can try exploring them for yourself.


Lights situated above EXIT signs help to identify passage ways. If you have not already done so, you should certainly investigate the influence of different Settings on how light may be used by the learner. Chapter 2 explains the importance of using different settings.

Improving understanding

Light by itself has little to offer the learner who is functioning at the level of Understanding. The principal area of use is helping Mobility (see Section 17)