Often an interaction in Adobe Captivate demands a different approach from a user with a disability. An example might be that a sighted user will click buttons on a slide to reveal information, while a visually impaired user might listen to information through a screen reader without ever clicking any buttons.
Usually, these different approaches do not affect the ability of a visually impaired learner from moving forward through an eLearning module. However, there are times when engaging in the interaction will actually trigger the appearance of a forward button. Obviously the learner who doesn't click can't trigger the forward button, so what can you do?
The answer is to add a hidden button somewhere on the slide that impaired learners will access with the keyboard. My colleagues will often place the hidden object on a slide's title banner--probably the least likely place for a sighted user to inadvertently click.
How does the visually impaired learner get there? I would suggest adding instructions, probably at the end of the information on the slide that tell the user to TAB to the forward button and press ENTER to proceed. Admittedly, a focus box will appear around the hidden object, but I find that this is more of an annoyance to a low vision user than a hindrance.