Microsoft PowerPoint Guidance
When a sighted person views a PowerPoint slide, they subconsciously take in a lot of information about the structure of the slide. This information needs to be available to users of screen readers too. When you have created your slide, always ask yourself what information is purely visual and whether that information is important in understanding the content. If it is, then you must ensure it can be perceived by a screen reader.
Understanding the role of the slide master in PowerPoint is helpful in building an accessible structure. It is only through the slide master that headings can be correctly marked up, but there are other advantages of using it too.
If you have a presentation with many slides, using sections can help provide structure. In PowerPoint, this is particularly helpful as the headings on the slides are limited to heading level 1 and 2.
For a sighted person, it is easy to see when a numbered or bulleted list is used. For a blind person, lists need to be created correctly so that their screen reader will announce the list and the items within it.
Tables in PowerPoint are not accessible to screen readers. It is best to avoid them completely.
Images and media
PowerPoint presentations tend to contain lots of content which is either visual or auditory in nature... sometimes both. It is important to consider how a blind or partially sighted person will access images and other visual content, and how a deaf or hearing impaired person will access audio content.
Images are, by nature, visual content. Unlike text, which can be read out loud by a screen reader, images are not inherently accessible to people with visual impairments. The only way a screen reader can announce an image in a meaningful way, is if the content producer gives it alt text. This alt text must be meaningful and useful, and it must be done correctly so that the screen reader can access it.
If you are using audio-only content in your slides, it is essential to provide a transcript, so that deaf people are able to access it. The transcript can be in a separate Word document and can be embedded as an object in your slide.
Videos are a great way to engage your audience. If you use videos, you must provide captions so that a deaf person can access the audio part of it. The usual way to do this is by adding closed captions. Alternatively, you could provide a full transcript.
You can find out more about video accessibility in the Perceivable section of the WCAG pages.
PowerPoint slides are made up of items, which usually need to be read in a particular order to make sense of them. Visually, we tend to read from top to bottom and from left to right. However, size, colour and formatting such as bold text can be used to influence the order that we read content. A screen reader reads the content in the order it was created, unless you tell it otherwise. One of the most important things you must do to make your PowerPoint slides accessible, is check and amend the reading order.
Colour is very important to visual people in helping them navigate and understand your content. Use of colour is not something to be avoided but rather to be considered from other perspectives. If it is used only as a supplementary tool, you probably have little to worry about. The problems occur where colour is the only means of understanding content. Where colour is used, think about how visually impaired people can access your content and also ensure that the colour contrast is sufficient.
Use of colour
Colour should never be used as the only means of conveying information. If you use colour to give information, you should also provide some kind of text that gives the same information. This will enable a screen reader user to access it.
For example, if you have an organisational chart that shows which teams people work in, you might choose to colour code the teams. It is perfectly acceptable to do this, but you must also make sure the teams are named and that the reading order is set so that the team members come after their team name.
PowerPoint slides are amongst the most common places that we see poor colour contrast. Whether this is due to background images or text box colours, poor contrast makes your slides difficult or impossible to read for people with colour blindness, low vision and when in bright light situations. Always check that your contrast passes a contrast check.
The guidance for creating accessible links in PowerPoint is the same as for most other contexts but in PowerPoint, it is common to see links used in more adventurous ways, and some of these are not accessible.
Always give your links meaningful text. Screen reader users can bring up lists of links as a navigational tool. If the links all say, "Click here," they are useless. In the same way, giving the full URL is rarely helpful, as these are read out in full.
It is possible to create buttons to navigate your PowerPoint slides. These are usually shapes containing text, which are linked to a different place within the same presentation. Buttons used in this way can cause difficulties for users of assistive software. Although they visually look like a button, they are not coded as buttons and don't tend to work with voice recognition software. They can also cause problems for users of screen readers. I would recommend avoiding them.
Checking your work
PowerPoint has a built in automatic accessibility checker. Like all automated tools, it has limitations, which is why I have left this until the end. The accessibility checker is a great way to identify features that you might have accidentally missed. However, you should try not to rely on it, as it only checks for some issues, not all. It is possible for the accessibility checker to give your slides a big thumbs up and yet your slides are totally inaccessible. It is just a tool.
Screen reader checks
The best way to check the accessibility of your slides is with a screen reader. It doesn't really matter which one you choose. They all have slightly different features but basically work in a similar way.