"Powerful, Scalable, Lightweight and Secure — for One Website or a Thousand
Deploy UserWay's advanced website accessibility solutions without refactoring your website's existing code and ensure a comprehensive legal & regulatory compliance framework covering ADA, Section 508, WCAG 2.1 AA, and much more."
Thats the official home page plug from UserWay. My take is that whilst the widget won't help everybody with visual impairment it does some great work and it is free.
IMHO every site should use this.