Time-permitting, I review the relevant lecture material with my access assistant ahead of office hours to be better prepared for students' questions. When students come to office hours with a question, I ask them to read it aloud, explain the question to me, and any steps they've taken thus far. By going through this process, students often find the answer for themselves or a mistake they may have made in solving the problem. This approach has the added benefit of helping my students to develop their communication skills.
My office hours are often well attended by students who have the same or similar questions. When the need arises to work through problems, I typically ask a student who understands the problem to walk their peers through the question on the low vision whiteboard in my office.
I also have an access assistant and/or a teaching assistant (TA) present in office hours as well. He/she helps support me when fielding questions and has the solutions on hand to visually check the work being done on the board.