Is there any reason you can't provide the same material as the slides in an email a day ahead? This at a minimum would give the blind person much better context for the presentation; whether they read it ahead of time, print it out in a form accessible to them (large print or braille), follow along using a device (braille display or text-to-speech on computer or smart phone).

Perhaps also try to minimize the slides. I don't know how much text you put on your slides or how many of them you have but you could try to reduce both the number of slides and amount of text.

If there are information graphics, org charts, diagrams try to convey this information non graphically in the email using bullets, tables or descriptions. Make sure to speak to the essential conclusions of the visual material; you don't need to describe it in it's entirety but you should quantitatively, if appropriate, describe the important part. ie. "Sales have risen quarter over quarter by at least 25% each quarter for the last year". Just reading the raw sales numbers for each quarter or even the increases would not be a substitute for the graph--most blind people are no better than anyone else at making sense of a jumble of numbers read at them. So think back to why you chose to present that graph and what you intended it to show and describe that.