How can I help my parent get her questions answered at the eye doctor's?

I suggest that your parent make a list of all of her questions and concerns and give it to the doctor (or to the nurse, who will give it to See also:
Why does my mother talk about health issues -- in excruciating detail?

See all 76 questions about Vision Problems the doctor with your mother's chart). Then all she has to do is ask him to look at the list and tell her the answers.

For questions that come up during the visit, it's fine for you to speak up on your mother's behalf, if you can anticipate any questions she might have. If you ask the doctor to explain something, your mother may see that that's an acceptable thing to do and follow suit. You can also ask her -- while you're still with the doctor -- if she has any questions or if there's anything that she doesn't understand.

Also, encourage your parent to call the office if she has questions after returning home. Some doctors even provide their e-mail address to patients who have follow-up questions.