PowerPoint's accessibility shortcomings
When compared to other Microsoft Office applications, PowerPoint's accessibility tools and features fall a little short. While the platform offers the basic tools you'll need to ensure slides and text can be parsed, it sorely lacks other enhancements like styles or even support for headings.
In other words, you cannot manually mark text as a heading, or divide complex slides into sections efficiently. This can make it difficult for users relying on assistive tools to understand the relationship of your content.
Can a presentation be fully accessible?
Whether a presentation is accessible or not is heavily dependant on that presentation's contents, layout, and design. Given the platform's limitations, not all designs can be made accessible. If slides are kept simple and linear, then it's possible to create a presentation that can be parsed and understood by users relying on assistive technologies. Calling PowerPoint an accessible platform is a bit of a stretch, though.
Whether that should deter you from using PowerPoint is entirely dependant on the type and the complexity of the information you want to disseminate. When it comes to accessibility, text will always trump over designs and visuals.
Microsoft 365 Online
At the time of writing, the online versions of Microsoft 365 applications entirely lack their desktop counterpart's accessibility tools. The desktop versions are therefore preferable if you're remediating or designing products with accessibility in mind.
Enabling the Accessibility tab
Before we can do any accessibility work on a presentation we'll need to enable the Accessibility tab, which PowerPoint does not display by default. To enable it, navigate to the Review tab and press the Check Accessibility button.
The tab will need to be toggled back on every time the application is launched unless added manually added to the ribbon menu. This can be done by right-clicking the ribbon menu and selecting Customize the ribbon. The Accessibility option can be found in the Tools tab section and can be moved to the Main tab.
Designing slides for accessibility
As mentioned previously, PowerPoint lacks information structuring tools. Because of that omission, we need to keep individual slides as simple and as linear as possible. Having more slides with less content is preferable over long, content-heavy ones.
As a general rule, focus on presenting one concept or topic per slide. Use title text for added clarity (which can also function as slide titles) and opt for designs that are less cluttered but rich in contextual information.
Smart Art
Smart Art components are treated as a single figure by screen readers. In other words, PowerPoint displays them like it would an image or a chart: only the alternative text value is provided to screen readers, rather than the component's contents and and text.
Try as I might, I could not find a way to make Smart Art parts easily accessible.
Because of this, I would generelly recommend against the use of Smart Art parts unless you can either easily resume their contents as alternative text or are willing to compose a text version.
Keep in mind that my findings may not reflect your reality. Various designs and patterns have their own strengths and faults, and the complexity will vary depending on the data you input.
Charts and graphs
As a general rule, try not to heavily rely on charts and graphs to convey information. Remember that every time you have a visual you also need to provide a text version of the data it presents.
From a design standpoint, I like to provide the data table on the left followed by the visual chart or graph on the right. The alternative text typically highlights the key points the graph or chart conveys.
When the data can't fit on the slide, create a new slide and mark it as invisible so it doesn't get presented by default. Add a link to that slide under your chart so that users can activate it to reach the text version.
Tables
Like most Microsoft Office applications, PowerPoint only supports basic table layouts. If you do include a table, avoid merging, splitting, or otherwise combining cells. In other words, keep your tables linear and don't forget to include row and column headers where appropriate.
I've previously written on writing accessible tables in HTML but the tips and tricks found in that article also apply to other formats, including PowerPoint.
Links
When adding links in PowerPoint presentations, add them to text that explains their destination. Avoid using generic, non-descriptive text like "click here" or "at the following address." Instead, use actions like "Consult our inventory" or self-descriptive text like "yearly earnings report."
Additionally, avoid providing the full URL in text format as long strings of URL text aren't particularly fun to go through with a screen reader.
Alternative text
Visual components like images and charts must contain a text description, commonly referred to as alternative text. Images and shapes that are used for decorative purposes should be marked as such.
To mark an element as decorative, right-click the element and select "View Alt Text" from the pop-up menu. In the panel, select "Mark as decorative." Alternatively, components can be marked as decorative in the Reading Order pane by checking them off the list.
Using colour
Ensure your foreground and background colours offer enough contrast to each other and that you aren't using colour alone to convey information or emphasis.
Don't forget about colour blindness, and take particular care when dealing with red and green hues. You can also use textures, arrows, or other ways to provide labels or legends.
Language
In a multilingual environment or when multiple people have edited the same file, you may find that some elements are marked in the wrong language. Using the wrong language can cause garbled speech when parsed with a screen reader but be remediated by overwriting the proofing language.
- Navigate to the View tab and select the Outline View.
- In the navigation pane that opens, press Ctrl+A to select all elements.
- Navigate to the Review tab and select Proofing language.
- Select the appropriate language from the list.
This will overwrite the language of every selected element. You can also set the language of individual elements should they be in a different language that the rest of the content.
Slide titles
Every slide must have a text box that is also used as the slide's title. Additionally, each title in the presentation must be unique and descriptive of the slide's contents.
To set a text box as the slide's title, select the box and, in the Accessibility tab, press the Slide Title button.
To view all titles, navigate to the View tab and select Outline View.
Invisible or hidden titles
In some cases, your slide may not have the room for a title or it might not suit the design. In that case, you can set a hidden title in the Slide Title button of the Accessibility tab.
Note that if you've previously set a title for the slide, the invisible slide title option may be unavailable. Should that be the case, you can create a text box and move it outside the slide's frame. This is essentially what the Hidden Slide Title feature does.
Reading order
When assistive tools like screen readers move through a slide, they follow a pre-set order that is specified in the presentation. It's critical that this reading order is reviewed, and that decorative elements are removed.
You can open the Reading Order pane from the ribbon menu's Accessibility tab. In the pane, drag items in the correct order or use the arrow buttons to move parts around.
Note that if you've used the reading order tool in previous versions of PowerPoint, the order was once bottom-to-top but is now inversed. This has been changed over the years and is now, thankfully, numbered to prevent any confusion.
You can validate your reading order by pressing the Tab key to move through the elements.
Renaming elements with the Selection Pane
As you set your elements reading order you're likely to notice that they, by default, have non-descriptive names like "textbox6" or "oval22." These titles can be changed in the Selection Pane. In the home tab, press the Select button in the Editing section and choose Selection Pane from the dropdown menu.
In the Selection Pane, select an object to highlight it and double-click the entry to rename it. Avoid reorganizing the order of items in this pane as it will also alter the reading order.
A warning on grouped elements
When multiple elements are grouped together, the reading order of its individual parts can no longer be changed or marked as decorative. Only the entire group can be altered.
In other words, if you have text in a group that otherwise contains decorative elements, you may inadvertently toggle off the group from the reading order.
Individual parts of a group can only be marked as decorative in the Selection Pane.
Best Practices
Accessibility validator
Microsoft PowerPoint includes a useful accessibility validation tool that outlines common issues such as missing alternative text, missing slide titles, tables with split or merged cells, issues with colours, and reading orders that should be reviewed.
The accessibility validator can be found in the Accessibility tab.
Exporting to PDF
In general, I recommend against the conversion of PowerPoint presentations to PDF. I've previously covered some of the accessibility pitfalls of the PDF format but moving from PowerPoint to PDF adds yet another layer of grime.
After the conversion, the document's tags will have to be manually reviewed and edited to add missing strutural elements. Tables, for example, will be exported as a <Figure> element, which is essentially treated as an image by screen readers. PowerPoint will also take a stab at marking title text as headings but in my experience it's pretty hit and miss.
In other words, there may be a lot of manual refinement required to make it work. You may find my write-up on PDF accessibility and my list of PDF tags helpful in this situation.
Takeaways
If nothing else, what I hope you take away from this guide is just how important it is to design your presentations with accessibility in mind from the start; it's exponentially more difficult, frustrating, and time consuming to remediate an inaccessible presentation than it would have been to do it right from the start.
By using simple slide layouts, ensuring a clear reading order, and by providing descriptive titles and alternative text for visual elements, your presentations can be made much more accessible to a wider audience, including those relying on assistive technologies.