Microsoft has also thouroughly detailed the process of using their accessibility features. See Make your PowerPoint presentations accessible.
Microsoft has extensive accessibility tools directly built into it's suite of office applications. They all share common tools to best assist the user in creating accessible documents. One common tool that is available for every Office 2016 application is called the Accessibility Checker. It allows you to quickly check an Office document for accessibility issues. See Microsoft's documentation on Use the Accessibility Checker on your Windows desktop to find accessibility issues.
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