Visitors who have visual problems require a little more effort. A fraction of your visitors may be colourblind. To be easily accessible to colourblind persons, insert colours that do not appear similar when viewed. You can hold trial sessions for colourblind people to give you an idea of the colour shades that you can safely use to maintain their distinct quality.
In case of totally blind visitors, the task can get tougher since normally, blind people use a screen reader software that reads out aloud one word at a time, one line at a time. This could be very frustrating for them since if the information that they require is at the bottom of the page, then the software would take up valuable time in reading through the entire page before reaching the bottom.
You should use adequate space between various words and make your alt-tag information short and precise. You can also place various key words in brackets and any accompany links by the word ‘link’, to make it easy for your blind visitors to understand and navigate.
The changes that required doing to cater to the special needs of your special visitors could well worth your while, since there might not be many sites thoughtful enough to incorporate them in their Websites. This could provide you and your business with financial as well as mental satisfaction.