Your audience is much more likely to hear what you have to say, understand what you just said and like you, if you make eye contact with them as you speak. So you should never make a presentation while staring at the screen.
If you need to look back and see what’s up, do it then face the audience and speak. Better yet is to have a laptop at the podium or on a table so you can refer to it while facing the audience.
But, even with that, it is for reference only. Hopefully, you know your presentation well enough that you don’t have to read it word by word.