To help ensure that your Office files are accessible, use the Accessibility Checker, a free tool available in Word, Excel, and PowerPoint on Windows or Mac. It finds accessibility issues and explains why each might be a potential problem for someone with a disability. It also offers suggestions to resolve each issue.
Accessibility Checker rules
The Accessibility Checker verifies your file against a set of rules that identify possible issues for people who have disabilities. Depending on how severe the issue is, the Accessibility Checker classifies each issue as an Error, Warning, or Tip.
Source for this page: Microsoft