You would need t contact them directly, as lanejudy suggested. When you purchase tickets, you are purchasing tickets for specific seats, so you need to plan where you are going to sit at the time you buy the tickets.
Here is a link to the ticket page for La Nouba.
https://shop.omniticket.com/wdw/wcq/index.cfm
It includes a special number for guests with special needs to use to contact them. It also includes a map of the theater seats.
We have not been to La Nouba, but have been to the Cirque du Soleil Beatles show in Las Vegas. If the theater is similar, you may not want to be in the very front - the action takes place in front but also all over and above stage, even above the seating area.
Being too close can make it hard to see the things not happening right in front of you and some of the things happening above.
What might be most important is to explain which eye you are legally blind in and how that affects your ability to see things on that side of you.
So, you might want to think things out a little bit before calling.
This page shows some pictures of the stage with riggings, so you can see a bit more where the action takes place ( a few pictures are of the seating/stage area, the rest are behind the scenes).
http://news.cnet.com/2300-13576_3-6241279-2.html