What she is referencing is Section 508 compliance; whereby if you offer a public service you must also cater to "visually impared users"; what you can take and do is have a contact page which users can sign up through as well and you'll be complaint.
You could additionally recommend that visually impared users utilize a screen magnifier, but that only helps with users who have some sense of sight.
My suggestion for this in the future is to have an auditory captcha, so that users who cannot *SEE* the text, can still *hear* it.
