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Chapter 3: Basic Principles and Ergonomics


It is hard to imagine modern society without computers. Also at schools they have almost become a part of daily life. For persons with visual impairment the computer is, if adapted in the right way, a great help in written communication and access to information.

A visually impaired person, who cannot read his/her own hand-written text, might be able to read an enlarged type of letter on a computer screen. If a person learns to touch-type quickly, their typing may be quicker then the writing of others. A blind person, for whom the tests always had to be transcribed into braille, can now read their test on the computer and correct mistakes.

If a visually impaired person is skillful in using the computer, this will benefit them throughout their life. During their education, on the job the computer can be a very suitable means for independent communication and obtaining information.

To teach a visually impaired pupil to use the computer is an important task. It means a base for success in their future. This module intends to give parents and teachers a helping hand in supporting this learning process.

General advice: “parents and teachers: keep your hands behind your back!”

Supporting and teaching visually impaired pupils requires special skills. The best support is often given with the instructors hands behind their back, without the teacher touching the keyboard or the mouse!

This means that the pupil has his hand on the “steering wheel” (the mouse and keyboard) and “steers” based upon questions from the teacher. This is an important starting-point, because a visually impaired pupil lacks the overview of the computer screen. They have to achieve this based upon questions from the teacher. Always help the pupil verbally and let him/her execute the actions. Avoid the “ I can do it for you more quickly”, and help the student to develop their own insights and decisions. It is important is that the student always:

  • Gets an overview over the whole screen, because the overview gets lost when using devices
  • Gets insight into cause and effect
  • Gets insight into his personal needs, e.g. “I need a dark background, a big mouse arrow and no light reflecting into the screen”

Basic principles and ergonomics

Visually impaired pupils

Blind pupils


Basic principles and ergonomics

In this section you will find a description of the optimal position of the computer and the person working with it. Important aspects are light, height and repetitive strain on the joints.

How do you place a computer?

Light reflection on the screen should be avoided.

What is a good position when working at the computer?

What discomforts can arise when a person becomes overburdened by repetitive strain?

How do you place a computer?

Keyboard, mouse, speakers and a screen are usually placed on a table. The screen should be placed at the height of the eye, so often you will find it on a stand or a swivel arm.

Light reflection on the screen should be avoided.

You can see this best when the screen is turned off. If you see light from outside or from a lamp, then there is reflection. In this case there is less contrast and the screen gets dimmer and less readable. So be aware of light from outside as well as from inside. Sometimes you can simply remove one lamp that is above the screen, without putting the whole classroom into darkness, or you can turn the screen a quarter turn or use curtains.

The computer usually sits on or just below the table so the student can easily reach to the on/off button, the disk drive and the CD-ROM player.

The printer and scanner are usually at a greater distance if they are being shared with other computers.

From the computer several electrical wires go to the screen, keyboard, mouse, printer, scanner and electric point. Safety first: see that no one is going to stumble over cords or wires.

What is a good position when working at the computer?

The back should be straight and supported by a backrest. The shoulders should be relaxed with the upper arms parallel to the persons sides. The angle between upper and lower arm should be approximately 90°. The hands should be suspended in a neutral position or be supported by a special soft wrist support. Usually the sitting height is adapted to the height of the table and changed by adjustment in the height of the chair. The angle between upper-and lower leg is 90°. In some cases footstool may be needed if the persons feet do not naturally reach the floor.

Distance from the screen should be 35-50 cm. The mouse should be on the right or on the left (depending on hand dominance) on a mouse mat that is usually square and corresponds with the dimension of the screen.

The ball of the thumb rests on the back of the mouse and three fingers (index, middle and third) are placed loosely on the mouse buttons. The mouse is held by the thumb and little finger and moved on the mat.

It is best the chair has a height adjustment feature.

All these indications can be used to consciously consider a good working position. (see illustration)

What discomforts can arise when a person becomes overburdened by repetitive strain?

One can easily work too long at the computer. This is a common cause for chronic pain to the joints. These symptoms can arise due to a sitting in a tensed position and repeating movements like: clicking with the mouse or typing for many hours.

In general our advice is to regularly take short breaks or vary the type of work being done There are several small programmes that can warn you in time.

Visually impaired pupils

For visually impaired pupils a good working position is extremely important.

As already mentioned, reflective light can influence the readability of the screen.

Because of their visual impairment many student have the tendency to sit bent over at a very short distance from the screen. This position leads to tension in neck and shoulders and eventually a problem within the joints.

When we ask for a good working position there are two conditions: -the screen should be adapted and -the pupil should know touch-typing. If this is not the case we cannot ask a pupil to maintain the right distance. It can be expected that if the student cannot read the screen or the letters on the keyboard he/she will tend to shorten the distance between their eyes and the screen and keyboard.

A good observation and interpretation of what you see will give you indications for your lessons. In this part we give you assistance with what you can expect to happen and how you can meet the needs of your student.

Distance to the screenTyping skills

Using mouse or keyboard?

Reference to the list of keyboard commands

Light and reflection

Combining reading printed/written text and working with the computer

Distance to the screen

The distance to the screen should be between 35 and 50 cm. This distance can be influenced by several factors, of which the most important are:

Type and size of font - You can choose different types and sizes. In general a font without serif, like Universal or Arial, is best. You can judge what is a good font for an individual by having him/her to read text in several types and sizes.

Influence of glasses - Another factor that is often underestimated is the effect of glasses on the reading distance. Reading glasses usually are adjusted to a reading distance of 25 cm. This is a normal reading distance for reading a book or magazine. Other distances give a less sharp image. A pupil who constantly keeps a 25 cm. distance could be wearing reading glasses for that distance. The size of the font does not have any major effect on the distance to the screen. Sometimes there is better result without the glasses or with glasses especially adapted for the computer screen.

If the pupil is reading “with his nose on the screen” or reading very slowly, it can mean several things. It might be the position he is used to working in, even if he could work at a greater distance. It might be advisable to seek suggestions on special devices for visually impaired pupils from a specialist teacher of children with visual impairment or an eye care professional. Such special devices offer many options for helping student to work at the computer with less strain.

Typing skills

The better a pupil can touch-type, the better his working position will be.

Many students learn touch-typing on a mechanical or electric typewriter and later switch to the computer keyboard. This switch does not generally present many significant challenges other that that the pupil needs to learn the location and function of the extra computer keys.

Touch-typing is the base for all computer work, so even if it is not very interesting to practice, it is extremely important and there should be a big emphasis on practice.

Using mouse or keyboard?

With Windows the use of the mouse has increased enormously.

On the screen you find icons with text to which you can point with the mouse and click to perform an action. But using the mouse is not the only way. You can also use keyboard commands. For most visually impaired students use of such keyboard command is advisable, because it provides a sure way to get where you want, to perform all actions and to do so, often more quickly than when using the mouse.

Reference to the list of keyboard commands

The speed of the movements of the mouse and the size of the mouse cursor are often reasons to reduce the use of the mouse by visually impaired persons. The mouse can be suitable in some cases for making large movements on the screen. This should be seen primary as a means for orientation on the screen.

The teacher should only on occasion use the mouse during instruction. To understand this you need to first think about what happens when you use the mouse. You see an icon on the screen and keep looking at it. Then you move the mouse into your visual field, to the icon to which you are still looking. Once icon and mouse are together, you click. Because you have to wait for the action to be performed you move the mouse from your visual field and you overlook the changing of the screen.

Your students looks at this in a different way. They will try to follow the mouse action until it stops. However, when the mouse seems to be still, there has already been a click, the mouse is moved again and the screen changes. Somewhere out of the blue the mouse appears and the student wonders what they have seen. This is why one should avoid using the mouse during instruction or support every action very carefully with verbal information.

Light and reflection

In the section on basic principles and ergonomics we talked about incidence of light and reflection of light into the screen. These basis principles we hope you will have adapted in creating a working place for your pupils. However, there is more to it. Light plays an important role in visibility and not always the same one. Where one pupil asks for more, the other might wish a lot less.

The light (brightness and contrast) of the screen itself can also be bothering. Usually there is a solution in using the buttons on the screen itself.

It is important for the teacher to realize that the needs of the students are very individually defined. Sometime a student is not aware of the circumstances under which he/she sees best.

The teacher can support him in getting this insight. For some eye diseases there are general guidelines (no laws!) for enlargement and light. You will find examples at the end of this module.

Combining reading printed/written text and working with the computer

Often students have to read text from books or readers and use the computer at the same time to do their exercises. If possible put the books at the same height as the computer screen, so the pupil does not have to bend over all the time to read. Usually the distance cannot be the same, because the printed letters are smaller then the letters on the screen. Sometimes a pupil will need a reading lamp for reading the printed text. In this case, see that the light does not reflect into the computer screen.

If a pupil needs a CCTV, the two screens can be combined into one, by using the computer screen for the CCTV as well, at the same time (“split screen”) or alternating.

This system also has some disadvantages, such as:

If you combine the two systems you lose even more overview than you did by using a CCTV

The camera of this type of CCTV may not provide the quality of the black and white contrast needed for reading text than a separate CCTV does. (at the time we are writing this module)

Blind pupils

The working position with the computer for a blind pupil often is better and more relaxed than that of a student with some vision.. There is obviously no need to bend over to the screen or keyboard.

When observing blind students that are working with an adapted computer with speech you may notice that they “look with their ears”; sometimes with their head cocked in the direction of the speaker. Good observation by will help. If the position on the student seems cramped you can try to put the synthesizer on a different spot.

Typing skills are as important for the blind students as for those with some remaining vision.

The blind pupil does not use the screen, but it is can very useful for the teacher when providing instruction. With blind pupils it is even more important that the teacher “keeps his/her hands behind their his back” and only gives verbal instruction.


If you are thinking of buying a computer it is advisable to take into consideration the following:

Your pupil’s present or future needs might have an effect on the kind of video card, sound card and the number of free slots the computer contains. For example, some enlargement programmes require a particular type of video card.

Any specific advice we give here will surely be outdated by the time you read this. So we advise you to turn to your local professional organisation for most up-to-date information.

For a visually impaired pupil the quality of the monitor is very important, because a good monitor can save a lot of energy! So it might be worth investing in a good screen.

Important aspects to consider concerning the monitor:

  • Size: 15, 17 or even larger. However, if the student has a visual field restriction, bigger does not necessarily mean better!

  • Radiation: since the visually impaired pupils tend to sit close to the screen you should strive for monitors that meet the highest safety standards.

  • Frequency: the higher the frequency (Htz), the more stable and still the image on the screen. This means that looking at the screen is less tiring at a 100 Htz. screen than at a 50 Htz screen. This can be very important, especially for student that have difficulties focussing.
  • The contrast and brightness adjustments should be extensive. Take the time to all options!

For a blind student the screen is not important of course. The screen is only used by the teacher; so a black and white screen will do. What you save here might be better invested in a really good soundcard.

Now you will find a list of tips to adapt the appearance of the screen, the mouse pointer and the fonts of texts, that you can make in Windows 95 and higher:

Adaptation of the colours: in Windows 95, 98 and 2000: you can change the appearance of the screen completely for every pupil. This is one of the first and most important things to do.

Go to: start button, control panel, display appearance scheme: e.g. “high contrast, windows standard big”. Here you can change colors, foreground and background, fonts and size of the menu bars, icons and a lot more items. You can save the scheme for every pupil individually. Every individual will have his own preferences, this becomes logical when you think of the fact that in general yellow/blue gives a bright contrast, but for someone with a certain type of colour-blindness this combination is the worst, he/she might need black/white!

Adaptation of the font in the text: In programmes like Word it is easy to change the font. Go to format fonts and choose a font sanserif, like Univers or Arial and choose the right size. Teach the pupil how to do this independently and how to adapt texts that are written in another size or font. (Control-a to select the whole text, and change the font) A very quick way to enlarge the font of an already written text is to select the text (control-a for the whole text; 1 x F8 for one sentence, 2 x F8 for one paragraph, 3 x F8 for the whole text), enlarge the font by pressing Control-> (which means Control-Shift-.)

this is Arial 12 this is Arial 16

Adaptation of the appearance of the program you’re working with to achieve as much room for the text as possible. Tidy up the screen!

  • Always maximize for maximum size

  • When you use keystrokes you don’t need a toolbar with icons or a layout toolbar

  • Most of the time you do not use the ruler so you can remove it

  • Use normal image (no page or oversight)

  • Use the zoom function
Adaptation of the mouse pointer: usually the software of the mouse contains possibilities to choose the size and contrast of the mouse pointer. Go to start button control panel mouse pointer and choose a large size and contrast.

Accessibility: In Windows a special program for disabled people can be found. For visually impaired pupils some parts can be useful, like the high contrast scheme and (limited) enlargement possibilities.

Using keystrokes instead of the mouse: Practically everything can be done using the keyboard by starting and closing programmes and documents, changing settings, layout of texts. For most visually impaired persons this method is a lot quicker and more secure. Keystrokes can be found in every handbook concerning computer programmes.

Chapter 1: Introduction to Assistive Technology

Chapter 2: Various Assistive Technologies

Chapter 4: Teaching People Who are Blind or Low Vision

Chapter 5: How do Blind/Vision Impaired Users Benefit from the internet

Chapter 6: Accessible Web Design

Chapter 7: Overbrook Resources

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